Skip to main content
Select Source:

Caffeine-related disorders

Caffeine-related disorders

Definition

Caffeine is a white, bitter crystalline alkaloid derived from coffee or tea. It belongs to a class of compounds called xanthines, its chemical formula being 1,3,7-trimethylxanthine. Caffeine is classified together with cocaine and amphetamines as an analeptic, or central nervous system stimulant. Coffee is the most abundant source of caffeine, although caffeine is also found in tea, cocoa, and cola beverages as well as in over-the-counter and prescription medications for pain relief.

In the clinician's handbook for diagnosing mental disorders (the Diagnostic and Statistical Manual of Mental Disorders , known as the DSM-IV-TR ), caffeine-related disorders are classified under the rubric of substance-related disorders. DSM-IV-TR specifies four caffeine-related disorders: caffeine intoxication, caffeine-induced anxiety disorder, caffeine-induced sleep disorder, and caffeinerelated disorder not otherwise specified. A fifth, caffeine withdrawal, is listed under the heading of "Criteria Sets and Axes Provided for Further Study."

Caffeine-related disorders are often unrecognized for a number of reasons:

  • Caffeine has a "low profile" as a drug of abuse. Consumption of drinks containing caffeine is unregulated by law and is nearly universal in the United States; one well-known textbook of pharmacology refers to caffeine as "the most widely used psychoactive drug in the world." In many countries, coffee is a social lubricant as well as a stimulant; the "coffee break" is a common office ritual, and many people find it difficult to imagine eating a meal in a fine restaurant without having coffee at some point during the meal. It is estimated that 1012 billion pounds of coffee are consumed worldwide each year.
  • People often underestimate the amount of caffeine they consume on a daily basis because they think of caffeine only in connection with coffee as a beverage. Tea, cocoa, and some types of soft drink, including root beer and orange soda as well as cola beverages, also contain significant amounts of caffeine. In one British case study, a teenager who was hospitalized with muscle weakness, nausea, vomiting, diarrhea, and weight loss was found to suffer from caffeine intoxication caused by drinking 8 liters (about 2 gallons) of cola on a daily basis for the previous two years. She had been consuming over a gram of caffeine per day. Chocolate bars and coffee-flavored yogurt or ice cream are additional sources of measurable amounts of caffeine.
  • Caffeine has some legitimate medical uses in athletic training and in the relief of tension-type headaches. It is available in over-the-counter (OTC) preparations containing aspirin or acetaminophen for pain relief as well as in such OTC stimulants as NoDoz and Vivarin.
  • Caffeine is less likely to produce the same degree of physical or psychological dependence as other drugs of abuse. Few coffee or tea drinkers report loss of control over caffeine intake, or significant difficulty in reducing or stopping consumption of beverages and food items containing caffeine.
  • The symptoms of caffeine intoxication are easy to confuse with those of an anxiety disorder.

The DSM-TR-IV states that it is unclear as of 2000 whether the tolerance, withdrawal symptoms, and "some aspects of dependence on caffeine" seen in some people who drink large amounts of coffee "are associated with clinically significant impairment that meets the criteria for Substance Abuse or Substance Dependence." On the other hand, a research team at Johns Hopkins regards caffeine as a model drug for understanding substance abuse and dependence. The team maintains that 9%30% of caffeine consumers in the United States may be caffeine-dependent according to DSM criteria for substance dependency.

Description

Pharmacological aspects of caffeine

An outline of the effects of caffeine on the central nervous system (CNS) and other organ systems of the body may be helpful in understanding its potential for physical dependence. When a person drinks a beverage containing caffeine (or eats coffee-flavored ice cream), the caffeine is absorbed from the digestive tract without being broken down. It is rapidly distributed throughout the tissues of the body by means of the bloodstream. If a pregnant woman drinks a cup of coffee or tea, the caffeine in the drink will cross the placental barrier and enter the baby's bloodstream.

When the caffeine reaches the brain , it increases the secretion of norepinephrine, a neurotransmitter that is associated with the so-called fight or flight stress response. The rise in norepinephrine levels and the increased activity of the neurons, or nerve cells, in many other areas of the brain helps to explain why the symptoms of caffeine intoxication resemble the symptoms of a panic attack .

The effects of caffeine are thought to occur as a result of competitive antagonism at adenosine receptors. Adenosine is a water-soluble compound of adenine and ribose; it functions to modulate the activities of nerve cells and produces a mild sedative effect when it activates certain types of adenosine receptors. Caffeine competes with adenosine to bind at these receptors and counteracts the sedative effects of the adenosine. If the person stops drinking coffee, the adenosine has no competition for activating its usual receptors and may produce a sedative effect that is experienced as fatigue or drowsiness.

Caffeine content of food items and OTC preparations

The caffeine content of various food items and medications is as follows:

  • Brewed coffee, 8-oz cup: 135150 mg
  • Instant coffee, 8-oz cup: 95 mg
  • Powdered cappuccino beverage, 8-oz cup: 4560 mg
  • Tea brewed from leaves or bag, 8-oz cup: 50 mg
  • Iced tea from mix, 8-oz glass: 2545 mg
  • Snapple iced tea, 8-oz glass: 21 mg
  • Mountain Dew, 8-oz glass: 38 mg
  • Dr. Pepper, 8-oz. glass: 28 mg
  • Diet cola, 8-oz glass: 31 mg
  • Root beer, 8-oz glass: 16 mg
  • Coffee ice cream, 8-oz serving: 6085 mg
  • Coffee yogurt, 8-oz serving: 45 mg.
  • Dark chocolate candy bar, 1.5 oz: 31 mg
  • NoDoz, regular strength, 1 tablet: 100 mg
  • NoDoz, maximum strength, 1 tablet: 200 mg
  • Excedrin, 2 tablets: 130 mg

Caffeine can produce a range of physical symptoms following ingestion of as little as 100 mg, although amounts of 250 mg or higher are usually needed to produce symptoms that meet the criteria of caffeine intoxication.

Caffeine intoxication

To meet DSM-IV-TR criteria for caffeine intoxication, a person must develop five or more of the twelve symptoms listed below; the symptoms must cause significant distress or impair the person's social or occupational functioning; and the symptoms must not be caused by a medical disorder or better accounted for by an anxiety disorder or other mental disorder.

Because people develop tolerance to caffeine fairly quickly with habitual use, caffeine intoxication is most likely to occur in those who consume caffeine infrequently or who have recently increased their intake significantly.

Caffeine-induced anxiety and sleep disorders

DSM-IV-TR criteria for caffeine-induced anxiety and sleep disorders specify that the symptoms of anxiety and insomnia respectively must be more severe than the symptoms associated with caffeine intoxication. In addition, the anxiety or insomnia must be severe enough to require separate clinical attention.

Causes and symptoms

Causes

The immediate cause of caffeine intoxication and other caffeine-related disorders is consumption of an amount of caffeine sufficient to produce the symptoms specified by DSM-IV-TR as criteria for the disorder. The precise amount of caffeine necessary to produce symptoms varies from person to person depending on body size and degree of tolerance to caffeine. Tolerance of the stimulating effects of caffeine builds up rapidly in humans; mild withdrawal symptoms have been reported in persons who were drinking as little as one to two cups of coffee per day.

Some people may find it easier than others to consume large doses of caffeine because they are insensitive to its taste. Caffeine tastes bitter to most adults, which may serve to limit their consumption of coffee and other caffeinated beverages. Slightly more than 30% of the American population, however, has an inherited inability to taste caffeine.

Symptoms

The symptoms of caffeine intoxication include:

  • restlessness
  • nervousness
  • excitement
  • insomnia
  • flushed face
  • diuresis (increased urinary output)
  • gastrointestinal disturbance
  • muscle twitching
  • talking or thinking in a rambling manner
  • tachycardia (speeded-up heartbeat) or disturbances of heart rhythm
  • periods of inexhaustibility
  • psychomotor agitation

People have reported ringing in the ears or seeing flashes of light at doses of caffeine above 250 mg. Profuse sweating and diarrhea have also been reported. Doses of caffeine higher than 10 g may produce respiratory failure, seizures , and eventually death.

Side effects and complications

High short-term consumption of caffeine can produce or worsen gastrointestinal problems, occasionally leading to peptic ulcers or hematemesis (vomiting blood).

In addition to the symptoms produced by high short-term doses, long-term consumption of caffeine has been associated with fertility problems and with bone loss in women leading to osteoporosis in old age. Some studies have found that pregnant women who consume more than 150 mg per day of caffeine have an increased risk of miscarriage and low birth weight babies, but the findings are complicated by the fact that most women who drink large amounts of coffee during pregnancy are also heavy smokers. Some researchers believe that long-term consumption of caffeine is implicated in cardiovascular diseases, but acknowledge that further research is required.

On the other hand, moderate doses of caffeine improve athletic performance as well as alertness. Caffeine in small doses can relieve tension headaches, and one study found that a combination of ibuprofen and caffeine was more effective in relieving tension headaches than either ibuprofen alone or a placebo. Coffee consumption also appears to lower the risk of alcoholic and nonalcoholic cirrhosis of the liver.

Drug interactions

Caffeine is often combined with aspirin or acetaminophen in over-the-counter and prescription analgesics (pain relievers). It can also be combined with ibuprofen. On the other hand, certain groups of drugs should not be combined with caffeine or taken with beverages containing caffeine. Oral contraceptives, cimetidine (Tagamet), mexiletine (Mexitil), and disulfiram (Antabuse) interfere with the breakdown of caffeine in the body. Caffeine interferes with the body's absorption of iron, and with drugs that regulate heart rhythm, including quinidine and propranolol (Inderal). Caffeine may produce serious side effects when taken together with monoamine oxidase inhibitors or with certain decongestant medications.

Combinations of ephedra and caffeine have been used in weight-loss programs because they produce greater weight loss than can be achieved by caloric restriction alone. Major studies were underway as of 2001 at Harvard and Vanderbilt to determine the safety of these regimens.

Practitioners of homeopathy have traditionally advised patients not to drink beverages containing caffeine in the belief that caffeine "antidotes" homeopathic remedies. Contemporary homeopaths disagree on the antidoting effects of caffeine, observing that homeopathy is used widely and effectively in Europe and that Europeans tend to drink strong espresso coffee more frequently than Americans.

Demographics

The general population of the United States has a high level of caffeine consumption, with an average intake of 200 mg per day. About 85% of the population uses caffeine in any given year. Among adults in the United States, about 30% consume 500 mg or more each day. These figures are lower, however, than the figures for Sweden, the United Kingdom, and other parts of Europe, where the average daily consumption of caffeine is 400 mg or higher. In developing countries, the average consumption of caffeine is much lower about 50 mg per day.

In the United States, levels of caffeine consumption among all races and ethnic groups are related to age, with usage beginning in the late teens and rising until the early 30s. Caffeine consumption tapers off in adults over 40 and decreases in adults over 65. Caffeine intake is higher among males than among females in North America.

The prevalence of caffeine-related disorders in the United States is not known as of 2002.

Diagnosis

Diagnosis of a caffeine-related disorder is usually based on the patient's recent history, a physical examination, or laboratory analysis of body fluids. In addition to medical evidence, the examiner will rule out other mental disorders, particularly manic episodes, generalized anxiety disorder , panic disorder , amphetamine intoxication, or withdrawal from sedatives, tranquilizers, sleep medications, or nicotine. All of these disorders or syndromes may produce symptoms resembling those of caffeine intoxication. In most cases, the temporal relationship of the symptoms to high levels of caffeine intake establishes the diagnosis.

In some cases, the examiner may consider the possibility of depression during the differential diagnosis, as many people with depression and eating disorders self-medicate with caffeine.

Treatments

Treatment of caffeine-related disorders involves lowering consumption levels or abstaining from beverages containing caffeine. Some people experience mild withdrawal symptoms that include headaches, irritability, and occasionally nausea, but these usually resolve quickly.

Caffeine consumption has the advantage of having relatively weak (compared to alcohol or cigarettes) social reinforcement , in the sense that one can easily choose a noncaffeinated or decaffeinated beverage in a restaurant or at a party without attracting comment. Thus physical dependence on caffeine is less complicated by the social factors that reinforce nicotine and other drug habits.

Prognosis

With the exception of acute episodes of caffeinism, people recover from caffeine intoxication without great difficulty.

Prevention

Prevention of caffeine-related disorders requires awareness of the caffeine content of caffeinated beverages, OTC drugs, and other sources of caffeine; monitoring one's daily intake; and substituting decaffeinated coffee, tea, or soft drinks for the caffeinated versions of these beverages.

Resources

BOOKS

American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders. 4th edition, text revised. Washington, DC: American Psychiatric Association, 2000.

"Anxiety Due to a Physical Disorder or a Substance." Section 15, Chapter 187. In The Merck Manual of Diagnosis and Therapy, edited by Mark H. Beers, MD, and Robert Berkow, MD. Whitehouse Station, NJ: Merck Research Laboratories, 1999.

Murray, Michael, ND, and Joseph Pizzorno, ND. Encyclopedia of Natural Medicine. Rocklin, CA: Prima Publishing, 1991.

O'Brien, Charles P. "Drug Addiction and Drug Abuse." Chapter 24 in Goodman & Gilman's The Pharmacological Basis of Therapeutics, edited by J. G. Hardman and L. E. Limbird. 9th edition. New York and St. Louis, MO: McGraw-Hill, 1996.

Pelletier, Kenneth R., MD. "Naturopathic Medicine." Chapter 7, in The Best Alternative Medicine. New York: Simon & Schuster, 2002.

PERIODICALS

Breslin, P. A. S., C. D. Tharp, D. R. Reed. "Selective Taste Blindness to Caffeine and Sucrose Octa Acetate: Novel Bimodal Taste Distributions Unrelated to PROP and PTC." American Journal of Human Genetics 69 (October 2001): 507.

"Caffeine Toxicity from Cola Consumption." Internal Medicine Journal 31 (2001): 317318.

Corrao, G. "Coffee, Caffeine, and the Risk of Liver Cirrhosis." Annals of Epidemiology 11 (October 2001): 458465.

De Valck, E., R. Cluydts. "Slow-Release Caffeine as a Countermeasure to Driver Sleepiness Induced by Partial Sleep Deprivation." Journal of Sleep Research 10 (September 2001): 203209.

Diamond, S., T. K. Balm, F. G. Freitag. "Ibuprofen Plus Caffeine in the Treatment of Tension-Type Headache." Clinical Pharmacology and Therapeutics 68 (2000): 312319.

Griffiths, R. R., and A. L. Chausmer. "Caffeine as a Model Drug of Dependence: Recent Developments in Understanding Caffeine Withdrawal, the Caffeine Dependence Syndrome, and Caffeine Negative Reinforcement." Nihon Shinkei Seishin Yakurigaku Zasshi 20 (November 2000): 223231.

MacFadyen, L., D. Eadie, T. McGowan. "Community Pharmacists' Experience of Over-the-Counter Medicine Misuse in Scotland." Journal of Research in Social Health 121 (September 2001): 185192.

Preboth, Monica. "Effect of Caffeine on Exercise Performance." American Family Physician 61 (May 2000): 628.

Rapurl, P. B., J. C. Gallagher, H. K. Kinyarnu, and others. "Caffeine Intake Increases the Rate of Bone Loss in Elderly Women and Interacts with Vitamin D Receptor Genotypes." American Journal of Clinical Nutrition 74 (2001): 694700.

Rumpler, William, James Seale, Beverly Clevidence, and others. "Oolong Tea Increases Metabolic Rate and Fat Oxidation in Men." Journal of Nutrition 131 (November 2001): 28482852.

Sardao, V. A., P. J. Oliveira, A. J. Moreno. "Caffeine Enhances the Calcium-Dependent Cardiac Mitochondrial Permeability Transition: Relevance for Caffeine Toxicity." Toxicology and Applied Pharmacology 179 (February 2002): 5056.

ORGANIZATIONS

American College of Sports Medicine. P. O. Box 1440, Indianapolis, IN 46206-1440. (317) 637-9200.

American Dietetic Association. (800) 877-1600. <www.eatright.org>.

Center for Science in the Public Interest (CSPI). <www.cspinet.org>.

Rebecca J. Frey, Ph.D.

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"Caffeine-related disorders." Gale Encyclopedia of Mental Disorders. . Encyclopedia.com. 12 Oct. 2018 <http://www.encyclopedia.com>.

"Caffeine-related disorders." Gale Encyclopedia of Mental Disorders. . Encyclopedia.com. (October 12, 2018). http://www.encyclopedia.com/psychology/encyclopedias-almanacs-transcripts-and-maps/caffeine-related-disorders

"Caffeine-related disorders." Gale Encyclopedia of Mental Disorders. . Retrieved October 12, 2018 from Encyclopedia.com: http://www.encyclopedia.com/psychology/encyclopedias-almanacs-transcripts-and-maps/caffeine-related-disorders

Learn more about citation styles

Citation styles

Encyclopedia.com gives you the ability to cite reference entries and articles according to common styles from the Modern Language Association (MLA), The Chicago Manual of Style, and the American Psychological Association (APA).

Within the “Cite this article” tool, pick a style to see how all available information looks when formatted according to that style. Then, copy and paste the text into your bibliography or works cited list.

Because each style has its own formatting nuances that evolve over time and not all information is available for every reference entry or article, Encyclopedia.com cannot guarantee each citation it generates. Therefore, it’s best to use Encyclopedia.com citations as a starting point before checking the style against your school or publication’s requirements and the most-recent information available at these sites:

Modern Language Association

http://www.mla.org/style

The Chicago Manual of Style

http://www.chicagomanualofstyle.org/tools_citationguide.html

American Psychological Association

http://apastyle.apa.org/

Notes:
  • Most online reference entries and articles do not have page numbers. Therefore, that information is unavailable for most Encyclopedia.com content. However, the date of retrieval is often important. Refer to each style’s convention regarding the best way to format page numbers and retrieval dates.
  • In addition to the MLA, Chicago, and APA styles, your school, university, publication, or institution may have its own requirements for citations. Therefore, be sure to refer to those guidelines when editing your bibliography or works cited list.

Caffeine

Caffeine

Caffeine is a naturally occurring stimulant found in the leaves, seeds, or fruit of over sixty plants around the world. Caffeine exists in the coffee bean in Arabia, the tea leaf in China, the kola nut in West Africa, and the cocoa bean in Mexico. Because of its use throughout all societies, caffeine is the most widely used psychoactive substance in the world. The most common caffeine sources in North America and Europe are coffee and tea. Since about 1980, extensive research has been conducted on how caffeine affects health. Most experts agree that moderate use of caffeine (300 milligrams, or about three cups of coffee, per day) is not likely to cause health problems.

How Caffeine Affects the Body

Caffeine is best known for its stimulant, or "wake-up," effect. Once a person consumes caffeine, it is readily absorbed by the body and carried around in the bloodstream, where its level peaks about one hour after consumption. Caffeine mildly stimulates the nervous and cardiovascular systems. It affects the brain and results in elevated mood, decreased fatigue , and increased attentiveness, so a person can think more clearly and work harder. It also increases the heart rate, blood flow, respiratory rate, and metabolic rate for several hours. When taken before bedtime, caffeine can interfere with getting to sleep or staying asleep.

Exactly how caffeine will affect an individual, and for how long, depends on many factors, including the amount of caffeine ingested, whether one is male or female, one's height and weight, one's age, and whether one is pregnant or smokes. Caffeine is converted by the liver into substances that are excreted in the urine.

Some people are more sensitive to the effects of caffeine than others. With frequent use, tolerance to many of the effects of caffeine will develop. At doses of 600 milligrams (about six cups of coffee) or more daily, caffeine can cause nervousness, sweating, tenseness, upset stomach, anxiety , and insomnia. It can also prevent clear thinking and increase the side effects of certain medications. This level of caffeine intake represents a significant health risk.

Caffeine can be mildly addictive. Even when moderate amounts of caffeine are withdrawn for 18 to 24 hours, one may feel symptoms such as headache, fatigue, irritability, depression , and poor concentration. The symptoms peak within 24 to 48 hours and progressively decrease over the course of a week. To minimize withdrawal symptoms, experts recommend reducing caffeine intake gradually.

Food/Beverage Caffeine (milligrams)
Coffee
Espresso coffee, brewed, 8 fluid ounces 502
Coffee, brewed, 8 fluid ounces 85
Coffee, instant, 8 fluid ounces 62
Coffee, brewed, decaffeinated, 8 fluid ounces 3
Coffee, instant, decaffeinated, 8 fluid ounces 2
Tea
Tea, brewed, 8 fluid ounces 47
Tea, herbal, brewed, 8 fluid ounces 0
Tea, instant, 8 fluid ounces 29
Tea, brewed, decaffeinated, 8 fluid ounces 3
Chocolate Beverages
Hot chocolate, 8 fluid ounces 5
Chocolate milk, 8 fluid ounces 5
Soft Drinks
Cola, 12 ounce can 37
Cola, with higher caffeine, 12 ounce can 100
Cola or pepper-type, diet, 12 ounce can 49
Cola or pepper-type, regular or diet, without caffeine, 12 ounce can 0
Lemon-lime soda, regular or diet, 12 ounce can 0
Lemon-lime soda, with caffeine, 12 ounce can 55
Ginger ale, regular or diet, 12 ounce can 0
Root beer, regular or diet, 12 ounce can 0
Chocolate
Milk chocolate bar, 1.55 ounces 9
M & M milk chocolate candies, 1.69 ounces 5
Dark chocolate, semisweet, 1 ounce 20
source: U.S. Department of Agriculture National Nutrient Database for Standard Reference, Release 16 July 2003.

Caffeine in Food and Drugs

Due to its stimulant properties, caffeine is used around the world in any of its many forms, such as coffee, tea, soft drinks, and chocolate. The accompanying table displays the amount of caffeine in foods. An eight-ounce cup of drip-brewed coffee has about 85 milligrams of caffeine, whereas the same amount of brewed tea contains about 47 milligrams. Twelve-ounce cans of soft drinks (soda) provide about 35 to 45 milligrams of caffeine.

The caffeine content of coffee and tea depends on the variety of the coffee bean or tea leaf, the particle size, the brewing method, and the length of brewing or steeping time. Brewed coffee has more caffeine than instant coffee, and espresso has more caffeine than brewed coffee. Espresso is made by forcing hot pressurized water through finely ground, dark-roast beans. Because it is brewed with less water, it contains more caffeine than regular coffee per fluid ounce.

In soft drinks, caffeine is both a natural and an added ingredient. About 5 percent of the caffeine in colas and pepper-flavored soft drinks is obtained naturally from cola nuts; the remaining 95 percent is added. Caffeine-free drinks contain virtually no caffeine and make up a small part of the soft-drink market.

Numerous prescription and nonprescription drugs also contain caffeine. Caffeine increases the ability of aspirin and other painkillers to do their job, and it is often used in headache and pain-relief remedies as well as in cold products and alertness or stay-awake tablets. When caffeine is an ingredient, it must be listed on the product label.

Caffeine and Health

Current research on how caffeine affects a variety of health issues is summarized below. Keep in mind that most experts agree that moderate use of caffeine is not likely to cause any health problems.

  • Studies have looked at the effects of caffeine on heart health. Moderate caffeine consumption does not appear to adversely affect cardiovascular health.
  • Caffeine appears to increase the excretion of calcium , a mineral needed for healthy bones. Calcium is particularly important to prevent osteoporosis , a bone disease characterized by loss of bone strength and seen especially in older women (although men get it too). Moderate caffeine intake does not seem to cause a problem with calcium, as long as one is consuming the recommended amount (adult men and women should be taking between 1,000 and 1,200 milligrams of calcium, depending on age and gender).
  • In the past there have been concerns that the caffeine in coffee may cause cancer . Research has shown that caffeine in coffee does not cause breast or intestinal cancer. However, not enough research has been done to determine if caffeine in coffee is involved in urinary bladder or pancreatic cancer. Taken in moderation, it is unlikely that caffeine will cause cancer.
  • Evidence suggests that, at levels over 500 milligrams per day, caffeine may delay conception. Moderate caffeine consumption does not appear to be of concern to women trying to get pregnant. Moderate consumption is also important for a healthy pregnancy. Excessive caffeine intake has been associated with miscarriages and low birth weight babies.
  • Because children have developing nervous systems, it is important to moderate their caffeine consumption. For children, major sources of caffeine include soft drinks and chocolate.
  • Caffeine may be useful as part of a weight control program because it increases the rate at which the body burns calories for three or more hours after being consumed.
  • Caffeine's ability to improve physical performance is well known among well-trained athletes. Through a mechanism that is not completely understood, caffeine seems to increase endurance and speed in some situations. Excessive use of caffeine is restricted in international competitions.

Karen Eich Drummond

Bibliography

Heaney, R. P. (2002). "Effects of Caffeine on Bone and the Calcium Economy." Food and Chemical Toxicology 40:12631270.

Juhn, M. S. (2002). "Ergogenic Aids in Aerobic Activity." Current Sports Medicine Reports 1:233238.

Kaiser, Lucia Lynn, and Allen, Lindsay. (2002). "Position of the American Dietetic Association: Nutrition and Lifestyle for a Healthy Pregnancy Outcome." Journal of the American Dietetic Association 102:14791490.

Nawrot, P.; Jordan, S.; Eastwood, J.; Rotstein, J.; Hugenholtz, A.; and Feeley, M. (2003). "Effects of Caffeine on Human Health." Food Additives and Contaminants 20:130.

Sizer, Frances, and Whitney, Eleanor. (2003). Nutrition: Concepts and Controversies. Belmont, CA: Wadsworth/Thomson Learning.

Smith, A. (2002). "Effects of Caffeine on Human Behavior." Food and Chemical Toxicology 40:12431255.

Weinberg, Bennett Alan, and Bealer, Bonnie K. (2002). The World of Caffeine: The Science and Culture of the World's Most Popular Drug. London: Taylor & Francis.

Internet Resource

Spriet, Lawrence L., and Graham, Terry. "Caffeine and Exercise Performance." American College of Sports Medicine. Available from <http://mplus.nlm.nih.gov/medlineplus>

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"Caffeine." Nutrition and Well-Being A to Z. . Encyclopedia.com. 12 Oct. 2018 <http://www.encyclopedia.com>.

"Caffeine." Nutrition and Well-Being A to Z. . Encyclopedia.com. (October 12, 2018). http://www.encyclopedia.com/food/news-wires-white-papers-and-books/caffeine

"Caffeine." Nutrition and Well-Being A to Z. . Retrieved October 12, 2018 from Encyclopedia.com: http://www.encyclopedia.com/food/news-wires-white-papers-and-books/caffeine

Learn more about citation styles

Citation styles

Encyclopedia.com gives you the ability to cite reference entries and articles according to common styles from the Modern Language Association (MLA), The Chicago Manual of Style, and the American Psychological Association (APA).

Within the “Cite this article” tool, pick a style to see how all available information looks when formatted according to that style. Then, copy and paste the text into your bibliography or works cited list.

Because each style has its own formatting nuances that evolve over time and not all information is available for every reference entry or article, Encyclopedia.com cannot guarantee each citation it generates. Therefore, it’s best to use Encyclopedia.com citations as a starting point before checking the style against your school or publication’s requirements and the most-recent information available at these sites:

Modern Language Association

http://www.mla.org/style

The Chicago Manual of Style

http://www.chicagomanualofstyle.org/tools_citationguide.html

American Psychological Association

http://apastyle.apa.org/

Notes:
  • Most online reference entries and articles do not have page numbers. Therefore, that information is unavailable for most Encyclopedia.com content. However, the date of retrieval is often important. Refer to each style’s convention regarding the best way to format page numbers and retrieval dates.
  • In addition to the MLA, Chicago, and APA styles, your school, university, publication, or institution may have its own requirements for citations. Therefore, be sure to refer to those guidelines when editing your bibliography or works cited list.

Caffeine

Caffeine

Description

Caffeine is a drug that stimulates the central nervous system (CNS). Caffeine is found naturally in coffee, Kola seed kernels or nuts (Cola nidtida ), and a variety of teas. Other foods and beverages, such as chocolate and soft drinks, also contain caffeine, and the drug can be purchased in over-the-counter tablet and capsule form (No Doz, Overtime, Pep-Back, Quick-Pep, Caffedrine, and Vivarin). Some prescription pain relievers, medicines for migraine headaches, and antihistamines also contain caffeine.

General use

Caffeine makes people more alert, less drowsy, and improves coordination. It is sometimes included in athletes' diets to improve physical performance. In addition, one recent study found that older people who were given a cup of caffeinated coffee in the morning had fewer late-day memory problems than those who were given decaffeinated coffee. Combined with certain pain relievers or medicines for treating migraine headache , caffeine makes those drugs work more quickly and effectively. Caffeine alone can also help relieve headaches. Antihistamines are sometimes combined with caffeine to counteract the drowsiness caused by those drugs. Caffeine is also sometimes used to treat other conditions, including breathing problems in newborns and in young babies after surgery.

Preparations

Kola can be prepared in decoction or tincture form. To prepare a decoction, mix 1-2 tsp of powdered kola nut in a cup of water . After bringing the water to a boil, simmer the decoction on low heat for 10-15 minutes. Tinctures of kola nut can be purchased at many health food stores or mail order suppliers. A tincture is an herbal preparation made by diluting the herb in alcohol, glycerin, or vinegar. Dosage of kola tincture varies by formula and the symptoms or illness it is supposed to treat, but an average recommended dosage might be 1-4 ml three times daily. Powdered kola nut and kola tinctures should be stored in airtight containers away from direct light to maintain potency.

For over-the-counter caffeine preparations, adults and children age 12 years and older should take 100-200 mg no more than every 3-4 hours. In timed-release form, the dose is 200-250 mg once a day. Timed-release forms should not be taken less than 6 hours before bedtime. Caffeine pills or tablets are typically not recommended for children under 12 years of age.

Precautions

If caffeine is administered in a kola preparation, kola should always be obtained from a reputable source that observes stringent quality control procedures and industry-accepted good manufacturing practices. Consumers should look for the designations "U.S.P." (U.S. Pharmacopeia) or "NF" (National Formulary) on kola nut labeling. Herbal preparations prepared under USP or NF guidelines meet nationally recognized strength, quality, purity, packaging, and labeling standards as recommended by the United States Food and Drug Administration (FDA).

CAFFEINE CONTENT OF COMMON DIETARY AND MEDICINAL SOURCES
Source Standard amount in milligrams (mg)
Bottled beverages (12 oz)
Red bull 115.5
Jolt 72
Mountain Dew 55
Diet Coke 45
Dr. Pepper 41
Coca Cola Classic 34
Coffee (8 oz)
Brewed 80135
Instant 65100
Decaf brew 34
Tea (8 oz)
Iced 47
Brewed 4060
Instant 30
Green 15
Chocolate
Hot cocoa (8 oz) 14
Chocolate milk (6 oz) 4
Chocolate bar (1 oz) 36
Medications (per tablet)
Vivarin 200
No-Doz 100
Midol, Maximum Strength 65
Anacin 32
Dristan 30

Avoid taking too much caffeine when it is being taken as an over-the-counter drug. Consider how much caffeine is being taken in from coffee, tea, chocolate, soft drinks, and other foods that contain caffeine. Check with a pharmacist or healthcare professional to find out how much caffeine is safe to use.

Caffeine cannot replace sleep and should not be used regularly to stay awake as the drug can lead to more serious sleep disorders , like insomnia .

People who use large amounts of caffeine over long periods build up a tolerance to it. When that happens, they have to use more and more caffeine to get the same effects. Heavy caffeine use can also lead to dependence. If an individual stops using caffeine abruptly, withdrawal symptoms may occur, including headache, fatigue , drowsiness, yawning, irritability, restlessness, vomiting , or runny nose. These symptoms can go on for as long as a week. In addition, caffeine dependence is not confined to the adult population. A study published in 2002 found that American teenagers have a high rate of caffeine dependence, partly because they consume large amounts of carbonated beverages that contain caffeine.

If taken too close to bedtime, caffeine can interfere with sleep. Even if it does not prevent a person from falling asleep, it may disturb sleep during the night.

The notion that caffeine helps people sober up after drinking too much alcohol is a myth. In fact, using caffeine and alcohol together is not a good idea. The combination can lead to an upset stomach, nausea , and vomiting.

Older people may be more sensitive to caffeine and thus more likely to have certain side effects, such as irritability, nervousness, anxiety , and sleep problems. Recent findings also suggest that people with insulin-dependent diabetes should monitor their caffeine intake. One study published in 2002 found that caffeine appears to decrease insulin sensitivity by about 15%.

Allergies

Anyone with allergies to foods, dyes, preservatives, or to the compounds aminophylline, dyphylline, oxtriphylline, theobromine, or theophylline should check with a physician before using caffeine. Anyone who has ever had an unusual reaction to caffeine should also check with a physician before using it again.

Pregnancy

Caffeine can pass from a pregnant woman's body into the developing fetus. Although there is no evidence that caffeine causes birth defects in people, it does cause such effects in laboratory animals given very large doses (equal to human doses of 12-24 cups of coffee a day). In humans, evidence exists that doses of more than 300 mg of caffeine a day (about the amount of caffeine in 2-3 cups of coffee) may cause miscarriage or problems with the baby's heart rhythm. Women who take more than 300 mg of caffeine a day during pregnancy are also more likely to have babies with low birth weights. Any woman who is pregnant or planning to become pregnant should check with her physician before using caffeine.

Breast-feeding

Caffeine passes into breast milk and can affect the nursing baby. Nursing babies whose mothers use 600 mg or more of caffeine a day may be irritable and have trouble sleeping. Women who are breast-feeding should check with their physicians before using caffeine.

Other medical conditions

Caffeine may cause problems for people with these medical conditions:

  • peptic ulcer
  • heart arrhythmias or palpitations
  • heart disease or recent heart attack (within a few weeks)
  • high blood pressure
  • liver disease
  • insomnia (trouble sleeping)
  • anxiety or panic attacks
  • agoraphobia (fear of being in open places)
  • premenstrual syndrome (PMS)

Side effects

At recommended doses, caffeine can cause restlessness, irritability, nervousness, shakiness, headache, light-headedness, sleeplessness, nausea, vomiting, and upset stomach. At higher than recommended doses, caffeine can cause excitement, agitation, anxiety, confusion, a sensation of light flashing before the eyes, unusual sensitivity to touch, unusual sensitivity of other senses, ringing in the ears, frequent urination, muscle twitches or tremors , heart arrhythmias, rapid heartbeat, flushing, and convulsions.

Interactions

Using caffeine with certain other drugs may interfere with the effects of the drugs or cause unwantedand possibly seriousside effects. Certain drugs interfere with the breakdown of caffeine in the body. These include oral contraceptives that contain estrogen, the antiarrhythmia drug mexiletine (Mexitil), the ulcer drug cimetidine (Tagamet), and the drug disulfiram (Antabuse), used to treat alcoholism .

Caffeine interferes with drugs that regulate heart rhythm, such as quinidine and propranolol (Inderal). Caffeine may also interfere with the body's absorption of iron . Anyone who takes iron supplements should take them at least an hour before or two hours after using caffeine.

Serious side effects are possible when caffeine is combined with certain drugs. For example, taking caffeine with the decongestant phenylpropanolamine can raise blood pressure. Very serious heart problems may occur if caffeine and monoamine oxidase inhibitors (MAO) are taken together. These drugs are used to treat Parkinson's disease, depression , and other psychiatric conditions. Consult with a pharmacist or physician about which drugs can interact with caffeine.

Because caffeine stimulates the nervous system, anyone taking other central nervous system stimulants should be careful about using caffeine.

Resources

BOOKS

Hoffman, David. The Complete Illustrated Herbal. New York: Barnes & Noble Books, 1999.

Medical Economics Corporation. The PDR for Herbal Medicines. Montvale, NJ: Medical Economics Corporation, 1998.

PERIODICALS

Bernstein, G. A., M. E. Carroll, P. D. Thuras, et al. "Caffeine Dependence in Teenagers." Drug and Alcohol Dependence 66 (March 2002): 1-6.

Keijzers, G. B., B. E. De Galan, et al. "Caffeine Can Decrease Insulin Sensitivity in Humans." Diabetes Care 25 (February 2002): 399-400.

Maughan, R. "The Athlete's Diet: Nutritional Goals and Dietary Strategies." Proceedings of the Nutrition Society 61 (February 2002): 87-96.

Ryan L., C. Hatfield, and M. Hostetter. "Caffeine Reduces Time-of-Day Effects on Memory Performance in Older Adults." Psychological Science 13 (January 2002): 68-71.

ORGANIZATIONS

Office of Dietary Supplements. National Institutes of Health. Building 31, Room 1B25, 31 Center Drive, MSC 2086, Bethesda, MD 20892-2086. (301) 435-2920. Fax: (301) 480-1845. http://odp.od.nih.gov/ods/ (Includes on-line access to International Bibliographic Information on Dietary Supplements (IBIDS), a database of published, international scientific literature on dietary supplements and botanicals).

Paula Ford-Martin

Rebecca J. Frey, PhD

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"Caffeine." Gale Encyclopedia of Alternative Medicine. . Encyclopedia.com. 12 Oct. 2018 <http://www.encyclopedia.com>.

"Caffeine." Gale Encyclopedia of Alternative Medicine. . Encyclopedia.com. (October 12, 2018). http://www.encyclopedia.com/medicine/encyclopedias-almanacs-transcripts-and-maps/caffeine-0

"Caffeine." Gale Encyclopedia of Alternative Medicine. . Retrieved October 12, 2018 from Encyclopedia.com: http://www.encyclopedia.com/medicine/encyclopedias-almanacs-transcripts-and-maps/caffeine-0

Learn more about citation styles

Citation styles

Encyclopedia.com gives you the ability to cite reference entries and articles according to common styles from the Modern Language Association (MLA), The Chicago Manual of Style, and the American Psychological Association (APA).

Within the “Cite this article” tool, pick a style to see how all available information looks when formatted according to that style. Then, copy and paste the text into your bibliography or works cited list.

Because each style has its own formatting nuances that evolve over time and not all information is available for every reference entry or article, Encyclopedia.com cannot guarantee each citation it generates. Therefore, it’s best to use Encyclopedia.com citations as a starting point before checking the style against your school or publication’s requirements and the most-recent information available at these sites:

Modern Language Association

http://www.mla.org/style

The Chicago Manual of Style

http://www.chicagomanualofstyle.org/tools_citationguide.html

American Psychological Association

http://apastyle.apa.org/

Notes:
  • Most online reference entries and articles do not have page numbers. Therefore, that information is unavailable for most Encyclopedia.com content. However, the date of retrieval is often important. Refer to each style’s convention regarding the best way to format page numbers and retrieval dates.
  • In addition to the MLA, Chicago, and APA styles, your school, university, publication, or institution may have its own requirements for citations. Therefore, be sure to refer to those guidelines when editing your bibliography or works cited list.

Caffeine

Caffeine

Definition

Caffeine is a drug that stimulates the central nervous system.

Purpose

Caffeine makes people more alert, less drowsy, and improves coordination. Combined with certain pain relievers or medicines for treating migraine headache, caffeine makes those drugs work more quickly and effectively. Caffeine alone can also help relieve headaches. Antihistamines are sometimes combined with caffeine to counteract the drowsiness that those drugs cause. Caffeine is also sometimes used to treat other conditions, including breathing problems in newborns and in young babies after surgery.

Description

Caffeine is found naturally in coffee, tea, and chocolate. Colas and some other soft drinks contain it. Caffeine also comes in tablet and capsule forms and can be bought without a prescription. Over-the-counter caffeine brands include No Doz, Overtime, Pep-Back, Quick-Pep, Caffedrine, and Vivarin. Some pain relievers, medicines for migraine headaches, and antihistamines also contain caffeine.

Recommended dosage

Adults and children age 12 years and over

100-200 mg no more than every 3-4 hours. In timed-release form, the dose is 200-250 mg once a day. Timed-release forms should not be taken less than six hours before bedtime.

Children under 12 years

Not recommended.

Other considerations

People should avoid taking much caffeine when it is being used as an over-the-counter drug and should consider how much caffeine is being taken in from coffee, tea, chocolate, soft drinks, and other foods that contain caffeine. A pharmacist or physician should be consulted to find out how much caffeine is safe to use.

Precautions

Caffeine cannot replace sleep and should not be used regularly to stay awake as the drug can lead to more serious sleep disorders, such as insomnia.

People who use large amounts of caffeine over long periods build up a tolerance to it. When this happens, they have to use more and more caffeine to get the same effects. Heavy caffeine use can also lead to dependence. If the person then stops using caffeine abruptly, withdrawal symptoms may occur. These can include throbbing headaches, fatigue, drowsiness, yawning, irritability, restlessness, vomiting, or runny nose. These symptoms can go on for as long as a week if caffeine is avoided. Then the symptoms usually disappear. As of 2004, caffeine withdrawal has been officially recognized as a disorder classification manual.

If taken too close to bedtime, caffeine can interfere with sleep. Even if it does not prevent a person from falling asleep, it may disturb sleep during the night.

The notion that caffeine helps people sober up after drinking too much alcohol is a myth. In fact, using caffeine and alcohol together is not a good idea. The combination can lead to an upset stomach, nausea, and vomiting.

Older people may be more sensitive to caffeine and thus more likely to have certain side effects, such as irritability, nervousness, anxiety, and sleep problems.

Special conditions

Caffeine may cause problems for people with certain medical conditions or who are taking certain medicines.

ALLERGIES. Anyone with allergies to foods, dyes, preservatives, or to the compounds aminophylline, dyphylline, oxtriphylline, theobromine, or theophylline should check with a physician before using caffeine. Anyone who has ever had an unusual reaction to caffeine should also check with a physician before using it again.

PREGNANCY. Caffeine can pass from a pregnant woman's body into the developing fetus. Although there is no evidence that caffeine causes birth defects in people, it does cause such effects in laboratory animals given very large doses (equal to human doses of 12-24 cups of coffee a day). In humans, evidence exists that doses of more than 300 mg of caffeine a day (about the amount of caffeine in 2-3 cups of coffee) may cause miscarriage or problems with the baby's heart rhythm. Women who take more than 300 mg of caffeine a day during pregnancy are also more likely to have babies with low birth weights. Any woman who is pregnant or planning to become pregnant should check with her physician before using caffeine.

BREASTFEEDING. Caffeine passes into breast milk and can affect the nursing baby. Nursing babies whose mothers use 600 mg or more of caffeine a day may be irritable and have trouble sleeping. Women who are breastfeeding should check with their physicians before using caffeine.

OTHER MEDICAL CONDITIONS. Caffeine may cause problems for people with these medical conditions:

  • peptic ulcer
  • heart arrhythmias or palpitations
  • heart disease or recent heart attack (within a few weeks)
  • high blood pressure
  • liver disease
  • insomnia (trouble sleeping)
  • anxiety or panic attacks
  • agoraphobia (fear of being in open places)
  • premenstrual syndrome (PMS)

USE OF CERTAIN MEDICINES. Using caffeine with certain other drugs may interfere with the effects of the drugs or cause unwantedand possibly seriousside effects.

Side effects

At recommended doses, caffeine can cause rest-lessness, irritability, nervousness, shakiness, headache, lightheadedness, sleeplessness, nausea, vomiting, and upset stomach. At higher than recommended doses, caffeine can cause excitement, agitation, anxiety, confusion, a sensation of light flashing before the eyes, unusual sensitivity to touch, unusual sensitivity of other senses, ringing in the ears, frequent urination, muscle twitches or tremors, heart arrhythmias, rapid heartbeat, flushing, and convulsions. High caffeine consumption can lead to benign breast disease, which also can increase risk of breast cancer.

Interactions

Certain drugs interfere with the breakdown of caffeine in the body. These include oral contraceptives that contain estrogen, the antiarrhythmia drug mexiletine (Mexitil), the ulcer drug cimetidine (Tagamet), and the drug disulfiram (Antabuse), used to treat alcoholism.

Caffeine interferes with drugs that regulate heart rhythm, such as quinidine and propranolol (Inderal). Caffeine may also interfere with the body's absorption of iron. Anyone who takes iron supplements should take them at least an hour before or two hours after using caffeine.

KEY TERMS

Arrhythmia Abnormal heart rhythm.

Central nervous system The brain and spinal cord.

Fetus A developing baby inside the womb.

Palpitation Rapid, forceful, throbbing, or fluttering heartbeat.

Withdrawal symptoms A group of physical or mental symptoms that may occur when a person suddenly stops using a drug to which he or she has become dependent.

Serious side effects are possible when caffeine is combined with certain drugs. For example, taking caffeine with the decongestant phenylpropanolamine can raise blood pressure. And serious heart problems may occur if caffeine and monoamine oxidase inhibitors (MAO) are taken together. These drugs are used to treat Parkinson's disease, depression, and other psychiatric conditions. A pharmacist or physician should be consulted about which drugs can interact with caffeine.

Because caffeine stimulates the nervous system, anyone taking other central nervous system (CNS) stimulants should be careful about using caffeine. Those trying to withdraw from caffeine are advised to do reduce their consumption slowly over time by substituting decaffeinated or non-caffeinated products for some of the caffeinated products.

Resources

PERIODICALS

"Caffeine Withdrawal Recognized as Disorder." Ascribe Health News Service September 29, 2004.

"High Caffeine Intake May Increase Risk of Benign Breast Disease." Womenós Health Weekly September 16, 2004: 32.

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"Caffeine." Gale Encyclopedia of Medicine, 3rd ed.. . Encyclopedia.com. 12 Oct. 2018 <http://www.encyclopedia.com>.

"Caffeine." Gale Encyclopedia of Medicine, 3rd ed.. . Encyclopedia.com. (October 12, 2018). http://www.encyclopedia.com/medicine/encyclopedias-almanacs-transcripts-and-maps/caffeine-1

"Caffeine." Gale Encyclopedia of Medicine, 3rd ed.. . Retrieved October 12, 2018 from Encyclopedia.com: http://www.encyclopedia.com/medicine/encyclopedias-almanacs-transcripts-and-maps/caffeine-1

Learn more about citation styles

Citation styles

Encyclopedia.com gives you the ability to cite reference entries and articles according to common styles from the Modern Language Association (MLA), The Chicago Manual of Style, and the American Psychological Association (APA).

Within the “Cite this article” tool, pick a style to see how all available information looks when formatted according to that style. Then, copy and paste the text into your bibliography or works cited list.

Because each style has its own formatting nuances that evolve over time and not all information is available for every reference entry or article, Encyclopedia.com cannot guarantee each citation it generates. Therefore, it’s best to use Encyclopedia.com citations as a starting point before checking the style against your school or publication’s requirements and the most-recent information available at these sites:

Modern Language Association

http://www.mla.org/style

The Chicago Manual of Style

http://www.chicagomanualofstyle.org/tools_citationguide.html

American Psychological Association

http://apastyle.apa.org/

Notes:
  • Most online reference entries and articles do not have page numbers. Therefore, that information is unavailable for most Encyclopedia.com content. However, the date of retrieval is often important. Refer to each style’s convention regarding the best way to format page numbers and retrieval dates.
  • In addition to the MLA, Chicago, and APA styles, your school, university, publication, or institution may have its own requirements for citations. Therefore, be sure to refer to those guidelines when editing your bibliography or works cited list.

Caffeine

Caffeine

Definition

Caffeine is a drug that stimulates the central nervous system.

Description

Caffeine is found naturally in coffee, tea, and chocolate. Colas and some other soft drinks contain it. Caffeine also comes in tablet and capsule forms and can be bought without a prescription. Over-the-counter caffeine brands include No Doz, Overtime, Pep-Back, Quick-Pep, Caffedrine, and Vivarin. Some pain relievers, medicines for migraine headaches, and antihistamines also contain caffeine.

General use

Caffeine makes people more alert, less drowsy, and improves coordination. Combined with certain pain relievers or medicines for treating migraine headache , caffeine makes those drugs work more quickly and effectively. Caffeine alone can also help relieve headaches. Antihistamines are sometimes combined with caffeine to counteract the drowsiness that those drugs cause. Caffeine is also sometimes used to treat other conditions, including breathing problems in newborns and in young babies after surgery.

Precautions

Caffeine cannot replace sleep and should not be used regularly for staying awake as the drug can lead to serious sleep disorders , like insomnia.

People who use large amounts of caffeine over long periods build up a tolerance to it. When that happens, they have to use more and more caffeine to get the same effects. Heavy caffeine use can also lead to dependence. If the person then stops using caffeine abruptly, withdrawal symptoms may occur. These can include throbbing headaches, fatigue, drowsiness, yawning, irritability, restlessness, vomiting , or runny nose. These symptoms can go on for as long as a week if caffeine is avoided. Then the symptoms usually disappear.

If taken too close to bedtime, caffeine can interfere with sleep. Even if it does not prevent a person from falling asleep, it may disturb sleep during the night.

The notion that caffeine helps people sober up after drinking too much alcohol is a myth. In fact, using caffeine and alcohol together is not a good idea. The combination can lead to an upset stomach, nausea , and vomiting.

Older people may be more sensitive to caffeine and thus more likely to have certain side effects, such as irritability, nervousness, anxiety , and sleep problems.

Children under the age of 12 should normally avoid caffeine.

Side effects

Although caffeine is used to treat headaches, regular consumption of large quantities of caffeine containing beverages can cause severe headaches.

Excess use of caffeine by children leads to decreased nighttime sleep, but increased daytime sleep.

Interactions

Certain drugs interfere with the breakdown of caffeine in the body. These include oral contraceptives that contain estrogen, the antiarrhythmia drug mexiletine (Mexitil), and the ulcer drug cimetidine (Tagamet).

Caffeine interferes with drugs that regulate heart rhythm, such as quinidine and propranolol (Inderal). Caffeine may also interfere with the body's absorption of iron. Anyone who takes iron supplements should take them at least an hour before or two hours after using caffeine.

Serious side effects are possible when caffeine is combined with certain drugs. For example, taking caffeine with the decongestant phenylpropanolamine can raise blood pressure. Very serious heart problems may occur if caffeine and monoamine oxidase (MAO) inhibitors are taken together. These drugs are used to treat Parkinson's disease, depression, and other psychiatric conditions. People who use these drugs should consult a pharmacist or physician about which drugs can interact with caffeine.

Because caffeine stimulates the nervous system, anyone taking other central nervous system (CNS) stimulants should be careful about using caffeine.

Parental concerns

Moderate amounts of caffeine are not normally associated with adverse effects. As a rule, a daily intake of 300 milligrams should not present a problem. The following list gives the estimated amount of caffeine in common foods, but actual concentrations may be higher or lower.

  • coffee, 115 mg
  • black tea, 40 mg
  • cola and other soft drinks, 18 mg
  • chocolate milk, 5 mg
  • milk chocolate (1 ounce) 6 mg

KEY TERMS

Arrhythmia Any deviation from a normal heart beat.

Central nervous system Part of the nervous system consisting of the brain, cranial nerves, and spinal cord. The brain is the center of higher processes, such as thought and emotion and is responsible for the coordination and control of bodily activities and the interpretation of information from the senses. The cranial nerves and spinal cord link the brain to the peripheral nervous system, that is the nerves present in the rest of body.

Withdrawal symptoms A group of physical and/or mental symptoms that may occur when a person suddenly stops using a drug or other substance upon which he or she has become dependent.

Resources

BOOKS

Beers, Mark H., and Robert Berkow, eds. The Merck Manual, 2nd home ed. West Point, PA: Merck & Co., 2004.

Mcevoy, Gerald, et al. AHFS Drug Information 2004. Bethesda, MD: American Society of Healthsystems Pharmacists, 2004.

Siberry, George K., and Robert Iannone, eds. The Harriet Lane Handbook, 15th ed. Philadelphia: Mosby Publishing, 2000.

PERIODICALS

Hering-Hanit, R., and N. Gadoth. "Caffeine-induced headache in children and adolescents." Cephalalgia 23, no. 5 (June 2003): 3325.

Pollak Charles P., and David Bright. "Caffeine consumption and weekly sleep patterns in U.S. seventh, eighth, and ninth graders." Pediatrics 111, no. 1 (January 2003): 426.

Steer, P. A., and D. J. Henderson-Smart. "Caffeine versus theophylline for apnea in preterm infants." Cochrane Database of Systematic Review 2 (2000): CD000273.

ORGANIZATIONS

Baylor College of Medicine USDA/ARS Children's Nutrition Research Center. 1100 Bates Street, Houston, TX 77030.

University of Minnesota Extension Service. Office of the Director, 240 Coffey Hall, 1420 Eckles Ave. St. Paul, MN 551086068.

WEB SITES

"Caffeine." Center for the Evaluation of Risks to Human Reproduction. Available online at <http://cerhr.niehs.nih.gov/genpub/topics/caffeine-ccae.html> (accessed October 16, 2004).

"Questions and Answers about Caffeine and Health." International Food Information Council. Available online at <www.ific.org/publications/qa/caffqa.cfm> (accessed October 16, 2004).

Nancy Ross-Flanigan Samuel Uretsky, PharmD

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"Caffeine." Gale Encyclopedia of Children's Health: Infancy through Adolescence. . Encyclopedia.com. 12 Oct. 2018 <http://www.encyclopedia.com>.

"Caffeine." Gale Encyclopedia of Children's Health: Infancy through Adolescence. . Encyclopedia.com. (October 12, 2018). http://www.encyclopedia.com/medicine/encyclopedias-almanacs-transcripts-and-maps/caffeine-2

"Caffeine." Gale Encyclopedia of Children's Health: Infancy through Adolescence. . Retrieved October 12, 2018 from Encyclopedia.com: http://www.encyclopedia.com/medicine/encyclopedias-almanacs-transcripts-and-maps/caffeine-2

Learn more about citation styles

Citation styles

Encyclopedia.com gives you the ability to cite reference entries and articles according to common styles from the Modern Language Association (MLA), The Chicago Manual of Style, and the American Psychological Association (APA).

Within the “Cite this article” tool, pick a style to see how all available information looks when formatted according to that style. Then, copy and paste the text into your bibliography or works cited list.

Because each style has its own formatting nuances that evolve over time and not all information is available for every reference entry or article, Encyclopedia.com cannot guarantee each citation it generates. Therefore, it’s best to use Encyclopedia.com citations as a starting point before checking the style against your school or publication’s requirements and the most-recent information available at these sites:

Modern Language Association

http://www.mla.org/style

The Chicago Manual of Style

http://www.chicagomanualofstyle.org/tools_citationguide.html

American Psychological Association

http://apastyle.apa.org/

Notes:
  • Most online reference entries and articles do not have page numbers. Therefore, that information is unavailable for most Encyclopedia.com content. However, the date of retrieval is often important. Refer to each style’s convention regarding the best way to format page numbers and retrieval dates.
  • In addition to the MLA, Chicago, and APA styles, your school, university, publication, or institution may have its own requirements for citations. Therefore, be sure to refer to those guidelines when editing your bibliography or works cited list.

Caffeine

Caffeine


Caffeine belongs to the family of heterocyclic compounds known as purines. It has the systematic name 3,7-dihydro-1,3,7-trimethyl-1H-purine-2,6-dione; it is also known as 1,3,7-trimethylxanthine, and 1,3,7-trimethyl-2,6-dioxopurine. Caffeine can be classified as an alkaloid , a term used for substances produced as end products of nitrogen metabolism in some plants. The chemical formula is C8H10N4O2. Caffeine has a molar mass of 194.19 grams (6.85 ounces). It is soluble in water and in many organic solvents, and it appears in pure form as white crystals. Caffeine can be prepared by extraction from natural sources or by synthesis from uric acid.

More than sixty plants, including those that give us coffee, tea, cola, and cacao, produce caffeine from the purine xanthine. Whereas caffeine is a natural constituent in coffee, tea, chocolate, and some cola drinks, it is added to consumer products such as soft drinks, diet pills, and analgesics . Caffeine is said to be the most widely used drug in the world, and more than 100 million people in the United States consume caffeine each day. It has pharmacological uses: as a cardiac and respiratory stimulant and as an agent that promotes kidney diuresis. A therapeutic dose of caffeine is about the same as the amount found in an average cup of coffee, between 100 and 200 milligrams (0.0071 ounces). Decaffeinated coffee can be prepared through extraction with a solvent (such as methylene chloride), water extraction, or steam extraction.

Caffeine enters the bloodstream about ten minutes after its ingestion and stays in the body for up to twelve hours. Like other alkaloids, caffeine has powerful physiological effects on humans and animals. It stimulates heart muscle and relaxes certain structures that contain smooth muscle, including the coronary arteries and the bronchi. It is a diuretic. Theophylline and theobromine, two other plant alkaloid derivatives of xanthine, have physiological effects similar to those of caffeine.

Caffeine acts as a stimulant of the central nervous system (CNS) through several proposed mechanisms. The most important seems to be its interference with the ability of the neurotransmitter adenosine to bind to its nerve cell receptor . Also, caffeine inhibits the enzyme cyclic nucleotide phosphodiesterase, which breaks down intracellular cyclic adenosine monophosphate (cAMP), another messenger involved in the transmission of nerve signals from hormones originating outside the central nervous system

such as epinephrine and glucagonhormones that initiate the "fight or flight" response in animals. Other proposed mechanisms have to do with effects on CNS intracellular calcium ion concentrations.

Caffeine is moderately habit-forming, but because caffeine users can usually control its use, it is not listed as an addicting stimulant by the American Psychiatric Association. Caffeine is not regarded as being harmful to the average healthy adult. In fact there are beneficial effects to be derived from moderate caffeine intake (about three cups of coffee per day). It relieves tiredness, improves thought processes, increases alertness, and enhances physical performance. It may be used to treat respiratory depression and, because it constricts blood vessels in the brain, is often an ingredient in headache remedies. There is some evidence that caffeine may help to mitigate symptoms of migraine headache and lower the risk of gallstones. Some studies show that caffeine may protect against Parkinson's disease, perhaps by inhibiting the depletion of the neurotransmitter dopamine in brain cells.

There may be some adverse effects due to excessive caffeine intake, such as restlessness, headaches, heart palpitations, heartburn, and insomnia. Some individuals may have a toxic reaction to it. Ingestion by pregnant women and nursing mothers may have adverse effects on fetuses and babies; caffeine crosses the placenta and gets into breast milk. Caffeine has a wide margin of safety. A lethal dose for most people would be the amount of caffeine found in about one hundred cups of coffee.

Some investigations into caffeine-related health issues are inconclusive. Studies have shown no correlation between caffeine intake and increased risk of osteoporosis or increased risk of spontaneous abortion. There is no conclusive evidence linking caffeine intake (as coffee) with bladder, pancreatic, breast, or colon cancer. There is also no conclusive evidence that moderate caffeine intake contributes to heart disease or heart arrhythmias; however, one study has shown that relatively high coffee consumption elevates blood levels of homocysteine (an amino acid)a situation that may contribute to heart attack or Alzheimer's disease. There is continuing controversy over whether heavy caffeine intake increases blood pressure, a woman's risk of developing breast lumps, or the incidence of miscarriage.

see also Dopamine; Epinephrine; Stimulants.

Sharron W. Smith

Bibliography

"Coffee: How Much Is Too Much?" (2001). Consumer Reports (May): 6465.

Other Resources

Merck Index, 12th edition. CD-ROM Version 12:1. (1996). London: Chapman and Hall.

Caffeine Archive. Available from <http://www.caffeinearchive.com>.

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"Caffeine." Chemistry: Foundations and Applications. . Encyclopedia.com. 12 Oct. 2018 <http://www.encyclopedia.com>.

"Caffeine." Chemistry: Foundations and Applications. . Encyclopedia.com. (October 12, 2018). http://www.encyclopedia.com/science/news-wires-white-papers-and-books/caffeine

"Caffeine." Chemistry: Foundations and Applications. . Retrieved October 12, 2018 from Encyclopedia.com: http://www.encyclopedia.com/science/news-wires-white-papers-and-books/caffeine

Learn more about citation styles

Citation styles

Encyclopedia.com gives you the ability to cite reference entries and articles according to common styles from the Modern Language Association (MLA), The Chicago Manual of Style, and the American Psychological Association (APA).

Within the “Cite this article” tool, pick a style to see how all available information looks when formatted according to that style. Then, copy and paste the text into your bibliography or works cited list.

Because each style has its own formatting nuances that evolve over time and not all information is available for every reference entry or article, Encyclopedia.com cannot guarantee each citation it generates. Therefore, it’s best to use Encyclopedia.com citations as a starting point before checking the style against your school or publication’s requirements and the most-recent information available at these sites:

Modern Language Association

http://www.mla.org/style

The Chicago Manual of Style

http://www.chicagomanualofstyle.org/tools_citationguide.html

American Psychological Association

http://apastyle.apa.org/

Notes:
  • Most online reference entries and articles do not have page numbers. Therefore, that information is unavailable for most Encyclopedia.com content. However, the date of retrieval is often important. Refer to each style’s convention regarding the best way to format page numbers and retrieval dates.
  • In addition to the MLA, Chicago, and APA styles, your school, university, publication, or institution may have its own requirements for citations. Therefore, be sure to refer to those guidelines when editing your bibliography or works cited list.

caffeine

caffeine is a methylxanthine present in tea and coffee, and therefore probably is the most common drug, regularly taken, in the world. Three very similar compounds — all in this same group of alkaloids — are present in common beverages, namely caffeine, theophylline, and theobromine. The first two are found mainly in tea and coffee, and the third in cocoa. Cola beans, used in the manufacture of well-known soft drinks, also contain caffeine. The three compounds differ very little from each other: simply the number and disposition of methyl groups about the xanthine nucleus is variable. Weight for weight, the caffeine content of coffee beans (0.7–1.5%) and tea leaves (2–3%) is similar, but generally a coffee infusion is stronger than that used for tea. Thus the dose of alkaloid per usual portion of tea or coffee is very similar, namely 50–150 mg, depending on taste.

Infusions made from the leaves of Camellia sinensis (i.e. tea) have been consumed in the East for almost two millenia, and the practice reached Europe in the sixteenth century. The demand grew, and plantations were started in the Indian subcontinent. The British remain the most constant tea drinkers, with an average annual consumption of 4.5 kg, equivalent to a daily caffeine intake of 300 mg. In Japan tea is made from powdered green leaves. An elaborate tea ceremony is sometimes performed in which the tea maker performs a series of ritualized procedures in a very precise way. The green tea served at these ceremonies is usually bitter in taste.

Coffee cultivation began in the Yemen in the ninth century, the beans being obtained from a bush, Coffea arabica, and they were introduced into Europe alongside tea in the sixteenth century. The major source of coffee is now in the state of Sao Paulo, Brazil. Coffee is supposed to have been discovered by an Ethiopian holy man whose goats had eaten the berries, allowing them to frisk all night long. It was claimed that coffee ‘quickens the spirits and makes the heart lightsome’ and is ‘good against the dropsy’, but a distinguished professor of medicine at Cambridge around 1900 claimed coffee caused tremors and agitation. Explanations for all these claims can be made, particularly when allowance is made for ‘dose’. However, assuming the effects are due to caffeine, tea drinkers as well as coffee drinkers will benefit, or suffer, alike. While lethargy and irritability often result from withdrawal in drinkers, it is doubtful whether true caffeine dependency exists.

The pharmacological effects of caffeine are widespread and various. By inhibition of certain enzymes, it allows an increase in the concentration of the ‘second messenger’, cyclic AMP, within cells, enhancing in turn the systems which this activates. Since caffeine penetrates the blood–brain barrier it is assumed that the central stimulant effects that enhance alertness and counteract feelings of fatigue, are due to this action. Caffeine also acts on the kidneys as a mild diuretic; this combined with its stimulant actions on heart muscle provide good evidence for the claim that it is ‘good for the dropsy’, both by strengthening the force of the heart beat and by removing accumulated body fluid.

Alan W. Cuthbert

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"caffeine." The Oxford Companion to the Body. . Encyclopedia.com. 12 Oct. 2018 <http://www.encyclopedia.com>.

"caffeine." The Oxford Companion to the Body. . Encyclopedia.com. (October 12, 2018). http://www.encyclopedia.com/medicine/encyclopedias-almanacs-transcripts-and-maps/caffeine

"caffeine." The Oxford Companion to the Body. . Retrieved October 12, 2018 from Encyclopedia.com: http://www.encyclopedia.com/medicine/encyclopedias-almanacs-transcripts-and-maps/caffeine

Learn more about citation styles

Citation styles

Encyclopedia.com gives you the ability to cite reference entries and articles according to common styles from the Modern Language Association (MLA), The Chicago Manual of Style, and the American Psychological Association (APA).

Within the “Cite this article” tool, pick a style to see how all available information looks when formatted according to that style. Then, copy and paste the text into your bibliography or works cited list.

Because each style has its own formatting nuances that evolve over time and not all information is available for every reference entry or article, Encyclopedia.com cannot guarantee each citation it generates. Therefore, it’s best to use Encyclopedia.com citations as a starting point before checking the style against your school or publication’s requirements and the most-recent information available at these sites:

Modern Language Association

http://www.mla.org/style

The Chicago Manual of Style

http://www.chicagomanualofstyle.org/tools_citationguide.html

American Psychological Association

http://apastyle.apa.org/

Notes:
  • Most online reference entries and articles do not have page numbers. Therefore, that information is unavailable for most Encyclopedia.com content. However, the date of retrieval is often important. Refer to each style’s convention regarding the best way to format page numbers and retrieval dates.
  • In addition to the MLA, Chicago, and APA styles, your school, university, publication, or institution may have its own requirements for citations. Therefore, be sure to refer to those guidelines when editing your bibliography or works cited list.

caffeine

caffeine (kăfēn´), odorless, slightly bitter alkaloid found in coffee, tea, kola nuts (see cola), ilex plants (the source of the Latin American drink maté), and, in small amounts, in cocoa (see cacao). It can also be prepared synthetically from uric acid. While relatively harmless, it is the most commonly used mind-altering drug in the world. When used in moderation, caffeine acts as a mild stimulant to the nervous system, blocking the neurotransmitter adenosine and resulting in a feeling of well-being and alertness. It increases the heart rate, blood pressure, and urination and stimulates secretion of stomach acids; excessive intake can result in restlessness, insomnia, and heart irregularities. The effects of caffeine vary from person to person, as people excrete it at different rates. Physical dependence and unpleasant symptoms upon withdrawal (headache, fatigue, depression) are common in regular caffeine users.

See B. A Weinberg and B. K. Bealer, The World of Caffeine (2001).

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"caffeine." The Columbia Encyclopedia, 6th ed.. . Encyclopedia.com. 12 Oct. 2018 <http://www.encyclopedia.com>.

"caffeine." The Columbia Encyclopedia, 6th ed.. . Encyclopedia.com. (October 12, 2018). http://www.encyclopedia.com/reference/encyclopedias-almanacs-transcripts-and-maps/caffeine-0

"caffeine." The Columbia Encyclopedia, 6th ed.. . Retrieved October 12, 2018 from Encyclopedia.com: http://www.encyclopedia.com/reference/encyclopedias-almanacs-transcripts-and-maps/caffeine-0

Learn more about citation styles

Citation styles

Encyclopedia.com gives you the ability to cite reference entries and articles according to common styles from the Modern Language Association (MLA), The Chicago Manual of Style, and the American Psychological Association (APA).

Within the “Cite this article” tool, pick a style to see how all available information looks when formatted according to that style. Then, copy and paste the text into your bibliography or works cited list.

Because each style has its own formatting nuances that evolve over time and not all information is available for every reference entry or article, Encyclopedia.com cannot guarantee each citation it generates. Therefore, it’s best to use Encyclopedia.com citations as a starting point before checking the style against your school or publication’s requirements and the most-recent information available at these sites:

Modern Language Association

http://www.mla.org/style

The Chicago Manual of Style

http://www.chicagomanualofstyle.org/tools_citationguide.html

American Psychological Association

http://apastyle.apa.org/

Notes:
  • Most online reference entries and articles do not have page numbers. Therefore, that information is unavailable for most Encyclopedia.com content. However, the date of retrieval is often important. Refer to each style’s convention regarding the best way to format page numbers and retrieval dates.
  • In addition to the MLA, Chicago, and APA styles, your school, university, publication, or institution may have its own requirements for citations. Therefore, be sure to refer to those guidelines when editing your bibliography or works cited list.

Caffeine

CAFFEINE

Caffeine is the world's most widely used behaviorally active drug. More than 80 percent of adults in North America consume caffeine regularly. Average per capita caffeine intakes in the United States, Canada, Sweden, and the United Kingdom have been estimated at 211 milligrams, 238 milligrams, 425 milligrams, and 444 milligrams per day, respectively; the world's per capita caffeine consumption is about 70 milligrams per day. These dose levels are well within the range of caffeine doses that can alter human behavior: As little as 32 milligrams of caffeine, less than the amount of caffeine in most 12-ounce cola soft drinks, can improve vigilance performance and reaction time; and doses as low as 10 milligrams, less than the amount of caffeine in some chocolate bars, can alter self-reports of mood. These data suggest that a large number of people are daily consuming behaviorally active doses of caffeine.

Caffeine-containing foods and beverages are ubiquitously available in and widely accepted by most contemporary societiesyet dietary doses of caffeine can produce behavioral effects that share characteristics with prototypic drugs of abuse: physical dependence, self-administration, and Tolerance. Chronic administration of only 100 milligrams of caffeine per day, the amount of caffeine in a cup of coffee, can produce Physical Dependence, as evidenced by severe and pronounced withdrawal symptoms that can occur upon abrupt termination of daily caffeine. Under some circumstances, research volunteers reliably self-administer dietary doses of caffeine, even when they are not informed that caffeine is the drug under study; and some evidence indicates that daily use of caffeine produces tolerance to caffeine's behavioral and physiological effects.

CLASS AND CHEMICAL STRUCTURE

Caffeine is an Alkaloid that is often classified as a central nervous system stimulant. Caffeine is structurally related to xanthine, a purine molecule with two oxygen atoms (see Figure 1). Several important compounds, including caffeine, consist of the xanthine molecule with methyl groups attached. A methyl group consists of a carbon atom and three hydrogen atoms. These methylated xanthines, called methylxanthines, are differentiated by the number and location of methyl groups attached to the xanthine molecule. Caffeine is a 1, 3, 7-trimethylxanthine. The "tri" refers to the fact that caffeine has three methyl groups. The "1, 3, 7" refers to the position of the methyl groups on the purine molecule. Other important methylxanthines include theophylline, theobromine, and paraxanthine. All these methylxanthines are metabolites of caffeine. In addition, theophylline and theobromine are ingested directly in some foods and medications.

SALIENT FEATURES

Sources.

Coffee and Tea are the world's primary dietary sources of caffeine. Other sources include soft drinks, cocoa products, and medications. Caffeine is found in more than sixty species of plants. Coffee is derived from the beans (seeds) of several species of Coffea plants, and the leaves of Camellia sinensis plants are used in caffeine-containing teas. Chocolate comes from the seeds or beans of the caffeine-containing cocoa pods of Theobroma cacao trees. In developed countries, soft drinks, particularly Colas, provide another common source of dietary caffeine. Only a portion of the caffeine in soft drinks comes from the kola nut (Cola nitida ); most of the caffeine is added during manufacturing. Since the 1960s, a marked decrease in coffee consumption in the United States has been accompanied by a substantial increase in the consumption of soft drinks. Maté leaves (Ilex paraguayensis ), guarana seeds, and yoco bark are other sources of caffeine for a variety of cultures. Table 1 shows the amounts of caffeine found in common dietary and medicinal sources. As can be seen in the range of values for each source in this table, the caffeine content can vary widely depending on method of preparation or commercial brand.

Effects on Mood and Performance.

It has long been believed that caffeine stimulates mood and behavior, decreasing fatigue and increasing energy, alertness, and activity. Although caffeine's effects in experimental studies have sometimes been subtle and variable, dietary doses of caffeine have a variety of effects on mood and performance. Doses below 200 milligrams have been shown to improve vigilance and reaction time, increase tapping speed, postpone sleep, and produce reports of increased alertness, energy, motivation to work, desire to talk to people, self-confidence, and well-being. Higher doses can both improve or disrupt performance of complex tasks, increase physical endurance, work output, hand tremor, and reports of nervousness, jitteriness, restlessness, and anxiousness.

DISCOVERY

Caffeine, derived from natural caffeine-containing plants, has been consumed for centuries by various cultures. Consumption of tea was first documented in China in 350 a.d., although there is some evidence that the Chinese first consumed tea as early as the third century b.c. Coffee cultivation began around 600 a.d., probably in what is now Ethiopia.

Caffeine was first chemically isolated from coffee beans in 1820 in Germany. By 1865, caffeine had been identified in tea, maté (a drink made from the leaves of a South American holly), and kola nuts (the chestnut-sized seed of an African tree).

THERAPEUTIC USES

Caffeine is incorporated in a variety of over-the-counter preparations marketed as analgesic, stimulant, cold, decongestant, menstrual-pain, or appetite-suppression medications. As an ingredient in Analgesics (painkillers), caffeine is used widely in the treatment of ordinary types of headaches, although evidence for caffeine's analgesic effects is limited: Caffeine may only diminish headaches that result from caffeine withdrawal, but it is also combined with an ergot Alkaloid in the treatment of migraine. Caffeine may have some therapeutic effectiveness in its ability to constrict cerebral blood vessels. The use of caffeine as a central nervous system (CNS) stimulant does have an empirical basis, but there is little evidence that caffeine has appetite-suppressant effects.

Because of various effects of caffeine on the respiratory system, caffeine is used to treat asthma, chronic obstructive pulmonary disease, and neonatal apnea (transient cessation of breathing in newborns)although other agents, including theophylline, are usually preferred for the treatment of asthma and chronic obstructive pulmonary disease.

Historically, caffeine has been used medically to treat overdoses with opioids and central depressants, but this use has decreased considerably with the development of alternative treatments.

ABUSE

Case reports have described individuals who consume large amounts of caffeineexceeding one gram per day (1,000 milligrams). This excessive intake, observed particularly among psychiatric patients, drug and alcohol abusers, and anorectic patients, can produce a range of symptomsmuscle twitching, Anxiety, restlessness, nervousness, insomnia, rambling speech, tachycardia (rapid heartbeat), cardiac arrhythmia (irregular heartbeat), psychomotor agitation, and sensory disturbances including ringing in the ears and flashes of light.

The disorder characterized by excessive caffeine intake has been referred to as caffeinism. There is some suggestion that excessive caffeine consumption can be linked to psychoses and anxiety disorders. Substantial amounts of caffeine are also used by a small percentage of competitive athletes, despite specific sanctions against such use.

Abused drugs are reliably self-administered under a range of environmental circumstances by humans and most are also self-administered by laboratory animals. Caffeine has been self-injected by laboratory nonhuman primates and self-administered orally and intravenously by rats, but there has been considerable variability across subjects and across studies.

Human self-administration of caffeine has been variable, as well; however it is clear that human subjects will self-administer caffeine, either in capsules or in coffee, and even when they are not informed that caffeine is the drug under study. For example, heavy coffee drinkers given repeated choices between capsules containing 100 milligrams caffeine or placebo under double-blind conditions showed clear preference for the caffeine capsules and, on average, consumed between 500 and 1,300 milligrams of caffeine per day. Experimental studies with low to moderate caffeine consumers have found that between 30 and 60 percent of those subjects reliably choose caffeine over placebo in blind-choice tests. Subjects tend to show less caffeine preference as the caffeine dose increases from 100 to 600 milligrams, and some subjects reliably avoid caffeine doses of 400 to 600 milligrams.

TOLERANCE

Chronic caffeine exposure can produce a decreased responsiveness to many of caffeine's effects (i.e., tolerance). This has been observed in both nonhumans and humans. Research with nonhumans has clearly demonstrated that chronic caffeine administration can produce partial tolerance to various effects of caffeine and can produce complete tolerance to caffeine's stimulating effect on locomotor activity in rats. A number of studies also suggest that tolerance to caffeine develops in humans: Daily doses of 250 milligrams of caffeine can increase systolic and diastolic blood pressure, however tolerance quickly develops to these effects within four days. The stimulating effects of caffeine on urinary and salivary output also diminish with chronic caffeine exposure. Although tolerance appears to develop to some of the central nervous system effects of caffeine, this aspect of caffeine tolerance has not been well explored. Comparisons of the effects of caffeine between heavy and light caffeine consumers provide indirect evidence that repeated (regular) caffeine use diminishes the sleep-disturbing effects and alters the profile of self-reported mood effects. For example, 300 milligrams of caffeine may produce self-reports of jitteriness in people who normally abstain from caffeine but not in regular caffeine consumers. High chronic caffeine doses (900 mg per day) can eliminate the self-reported mood effects (tension, anxiety, nervousness and jitteriness) of 300 milligrams of caffeine given twice a day.

PHYSICAL DEPENDENCE

Evidence of physical dependence on caffeine is provided by the appearance of a withdrawal syndrome following abrupt termination of daily caffeine. Although there have been relatively few demonstrations of caffeine withdrawal in nonhumans, abrupt termination of chronic daily caffeine has been shown to clearly decrease locomotor behavior in rats. Considerably more is known about caffeine withdrawal in humans. Caffeine withdrawal is well documented in anecdotal case reports dating back to the 1800s and in experimental and survey studies from the 1930s to the present. Caffeine withdrawal is typically characterized by reports of headache, fatigue (e.g., reports of mental depression, weakness, lethargy, sleepiness, drowsiness, and decreased alertness), and possibly anxiousness. Descriptions of the withdrawal headache suggest that it develops gradually and can be throbbing and severe.

When caffeine withdrawal occurs, its intensity can vary from mild to severe. Anecdotal descriptions of severe withdrawal suggest that it can be incompatible with normal functioning and include flulike symptoms, fatigue, severe headache, nausea, and vomiting. In general, caffeine withdrawal begins twelve to twenty-four hours after terminating caffeine, peaks at twenty to forty-eight hours, and lasts from two to seven days. Caffeine withdrawal can occur following termination of caffeine doses as low as 100 milligrams per day, an amount equal to one strong cup of coffee, two strong cups of tea, or three soft drinks. Caffeine withdrawal effects can vary within an individual in that a given individual may not experience caffeine withdrawal during every period of caffeine abstinence. The severity of the withdrawal symptoms usually appears to be an increasing function of the maintenance dose of caffeine. Caffeine suppresses caffeine withdrawal symptoms in a dose-dependent manner, so that the magnitude of suppression increases as a function of the administered caffeine dose.

The data described above indicate that the large majority of the adult population in the United States is at risk for periodically experiencing significant disruption of mood and behavior when there are interruptions of daily caffeine consumption.

The nature and time course of effects of terminating daily caffeine consumption is illustrated in Figure 2, a recent experiment involving seven adult subjects. The subjects followed a caffeine-free diet throughout the study and received identically appearing capsules daily. Prior to the study, subjects had received 100 milligrams of caffeine daily for more than 100 days. Placebo capsules were substituted for caffeine without the subjects' knowledge, and subjects continued to receive placebo capsules for twelve days, after which caffeine administration was resumed. The top panel of the figure shows that substitution of placebo for caffeine produced statistically significant increases (asterisks) in the average ratings of headache during the first two days of placebo substitution. Headache ratings gradually decreased over the next twelve days and continued at low levels during the final caffeine condition. The bottom panel of the figure shows that substitution of placebo for caffeine produced similar time-limited increases in subjects' ratings of lethargy/fatigue/tired/sluggish.

ORGAN SYSTEMS

Caffeine affects the cardiovascular, respiratory, gastrointestinal and central nervous systems. Most notably, caffeine stimulates cardiac muscles, relaxes smooth muscles, produces diuresis by acting on the kidney, and stimulates the central nervous system. The potential of dietary doses of caffeine to stimulate the central nervous system is primarily inferred from caffeine's behavioral effects. Low to moderate caffeine doses can produce changes in mood (e.g., increased alertness) and performance (e.g., improvements in vigilance and reaction time). Higher doses produce reports of nervousness and anxiousness, measurable disturbances in sleep, and increases in tremor. Very high doses can produce convulsions.

Caffeine's cardiovascular effects are variable and depend on dose, route of administration, rate of administration, and history of caffeine consumption. Caffeine doses between 250 and 350 milligrams can produce small increases in blood pressure in caffeine-abstinent adults. Daily caffeine administration, however, produces tolerance to these cardiovascular effects within several days; thus comparable caffeine doses do not reliably affect blood pressure of regular caffeine consumers. High caffeine doses can produce a rapid heartbeat (tachycardia) and in rare cases irregularities in heartbeat (cardiac arrhythmia). Caffeine's effects on peripheral blood flow and vascular resistance are variable. In contrast, caffeine appears to increase cerebrovascular resistance and decrease cerebral blood flow.

Moderate doses of caffeine can increase respiratory rate in caffeine-abstinent adults. Caffeine also relaxes the smooth muscles of the bronchi. Because of caffeine effects on respiration, it has been used to treat asthma, chronic obstructive pulmonary disease, and neonatal apnea (transient cessation of respiration in newborns).

Moderate doses of caffeine can act on the kidney to produce diuretic effects that diminish after chronic dosing. Caffeine has a variety of effects on the gastrointestinal system, particularly the stimulation of acid secretion. These effects can contribute to digestive upset and to ulcers of the gastrointestinal system.

Caffeine increases the concentration of free fatty acids in plasma and increases the basal metabolic rate.

TOXICITY

High doses of caffeine, typically doses above 300 milligrams, can produce restlessness, anxiousness, nervousness, excitement, flushed face, diuresis, gastrointestinal problems, and headache. Doses above 1,000 milligrams can produce rambling speech, muscle twitching, irregular heartbeat, rapid heartbeat, sleeping difficulties, ringing in the ears, motor disturbances, anxiety, vomiting, and convulsions. Adverse effects of high doses of caffeine have been referred to as caffeine intoxication, a condition recognized by the American Psychiatric Association. Extremely high doses of caffeinebetween 5,000 and 10,000 mgcan produce convulsions and death.

Extremely high doses of caffeine, well above dietary amounts, have been shown to produce teratogenic effects (birth defects) in mammals. Although there is some evidence to the contrary, dietary doses of caffeine do not appear to affect the incidence of malformations or of low-birth-weight offspring. Although there has been some suggestion that caffeine consumption increases the incidence of benign fibrocystic disease and cancer of the pancreas, kidney, lower urinary tract, and breast, associations have not been clearly established between caffeine intake and any of these conditions. Similarly, dietary caffeine has been associated with little, if any, increase in the incidence of heart disease.

Controversies continue over the medical risks of caffeine. Although research has not definitively resolved all the controversies, health-care professionals must make recommendations regarding safe and appropriate use of caffeine. In a recent survey of physician specialists, more than 65 percent recommended reductions in caffeine in patients with arrhythmias, palpitations, tachycardia, esophagitis/hiatal hernia, fibrocystic disease, or ulcers, as well as in patients who are pregnant.

PHARMACOKINETICS

Absorption and Distribution.

Caffeine can be effectively administered orally, rectally, intramuscularly, or intravenously; however, it is usually administered orally. Orally consumed caffeine is rapidly and completely absorbed into the bloodstream through the gastrointestinal tract, producing effects in as little as fifteen minutes and reaching peak plasma levels within an hour. Food reduces the rate of absorption. Caffeine readily moves through all cells and tissue, largely by simple diffusion, and thus is distributed to all body organs, quickly reaching equilibrium between blood and all tissues, including brain. Caffeine crosses the placenta, and it passes into breast milk.

Metabolism and Excretion.

The bloodstream delivers caffeine to the liver, where it is converted to a variety of metabolites. Most of an ingested dose of caffeine is converted to paraxanthine and then to several other metabolites. A smaller proportion of caffeine is converted to theophylline and theobromine; both of those compounds are also further metabolized. Some of these metabolites may contribute to caffeine's physiologic and behavioral effects.

The amount of time required for the body of an adult to remove half of an ingested dose of caffeine (i.e., the half-life) is 3 to 7 hours. On average, about 95 percent of a dose of caffeine is excreted within 15 to 35 hours. Cigarette smoking produces a twofold increase in the rate at which caffeine is eliminated from the body. There is a twofold decrease in the caffeine elimination rate in women using oral contraceptive steroids and during the later stages of pregnancy. Newborn infants eliminate caffeine at markedly slower rates, requiring over 10 days to eliminate about 95 percent of a dose of caffeine. By 1 year of age, caffeine elimination rates increase substantially, exceeding those of adults; school-aged children eliminated caffeine twice as fast as adults.

MECHANISMS OF ACTION

Three mechanisms by which caffeine might exert its behavioral and physiological effects have been proposed: (1) blockade of receptors for adenosine; (2) inhibition of phosphodiesterase activity resulting in accumulation of cyclic nucleotides; and (3) translocation of intracellular calcium. Only one of these, however, the blockade of adenosine receptors, occurs at caffeine concentrations in plasma produced by dietary consumption of caffeine. Adenosine (an autacoidor cell-activity modifier), found throughout the body, has a variety of effects that are often opposite to caffeine's effectsalthough caffeine is structurally very similar to adenosine. As a result, caffeine can bind to the receptor sites normally occupied by adenosine, thereby blocking adenosine binding, and preventing adenosine's normal activity. Thus, caffeine's ability to stimulate the central nervous system, and increase urine output and gastric secretions, may be due to the blockade of adenosine's normal tendency to depress the central nervous system and decrease urine output and gastric secretions. The methylxanthine metabolites of caffeine (including paraxanthine, theophylline, and theobromine) are also structurally similar to adenosine and block adenosine binding.

(See also: Addiction: Concepts and Definitions ; Tolerance and Physical Dependence )

BIBLIOGRAPHY

Dews, P.B. (Ed.) (1984). Caffeine. New York: Springer-Verlag.

Graham, D. M. (1978). CaffeineIts identity, dietary sources, intake and biological effects. Nutrition Reviews, 36, 97-102.

Griffiths, R. R., & Woodson, P. P. (1988). Caffeine physical dependence: A review of human and laboratory animal studies. Psychopharmacology, 94, 437-51.

Griffiths, R. R., et al. (1990). Low-dose caffeine physical dependence in humans. Journal of Pharmacological and Experimental Therapy, 255, 1123-1132.

Hughes, J. R., Amori, G., & Hatsukami, K. D. (1988). A survey of physician advice about caffeine. Journal of Substance Abuse, 1, 67-70.

Rall, T. W. (1990). Drugs used in the treatment of asthma. In A. G. Gilman et al. (Eds.), Goodman and Gilman's the pharmacological basis of therapeutics, 8th ed. New York: Pergamon.

Spiller, G.A. (Ed.) (1984). The methylxanthine beverages and foods: Chemistry, consumption, and health effects. New York: Alan R. Liss.

Weiss, B., & Laties, V. G. (1962). Enhancement of human performance by caffeine and the amphetamines. Pharmacological Review, 14, 1-36.

Kenneth Silverman

Roland R. Griffiths

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"Caffeine." Encyclopedia of Drugs, Alcohol, and Addictive Behavior. . Encyclopedia.com. 12 Oct. 2018 <http://www.encyclopedia.com>.

"Caffeine." Encyclopedia of Drugs, Alcohol, and Addictive Behavior. . Encyclopedia.com. (October 12, 2018). http://www.encyclopedia.com/education/encyclopedias-almanacs-transcripts-and-maps/caffeine

"Caffeine." Encyclopedia of Drugs, Alcohol, and Addictive Behavior. . Retrieved October 12, 2018 from Encyclopedia.com: http://www.encyclopedia.com/education/encyclopedias-almanacs-transcripts-and-maps/caffeine

Learn more about citation styles

Citation styles

Encyclopedia.com gives you the ability to cite reference entries and articles according to common styles from the Modern Language Association (MLA), The Chicago Manual of Style, and the American Psychological Association (APA).

Within the “Cite this article” tool, pick a style to see how all available information looks when formatted according to that style. Then, copy and paste the text into your bibliography or works cited list.

Because each style has its own formatting nuances that evolve over time and not all information is available for every reference entry or article, Encyclopedia.com cannot guarantee each citation it generates. Therefore, it’s best to use Encyclopedia.com citations as a starting point before checking the style against your school or publication’s requirements and the most-recent information available at these sites:

Modern Language Association

http://www.mla.org/style

The Chicago Manual of Style

http://www.chicagomanualofstyle.org/tools_citationguide.html

American Psychological Association

http://apastyle.apa.org/

Notes:
  • Most online reference entries and articles do not have page numbers. Therefore, that information is unavailable for most Encyclopedia.com content. However, the date of retrieval is often important. Refer to each style’s convention regarding the best way to format page numbers and retrieval dates.
  • In addition to the MLA, Chicago, and APA styles, your school, university, publication, or institution may have its own requirements for citations. Therefore, be sure to refer to those guidelines when editing your bibliography or works cited list.

caffeine

caffeine An alkaloid (chemically trimethylxanthine) found in coffee and tea (when it is sometimes called theine). It raises blood pressure, stimulates the kidneys, and temporarily averts fatigue and tiredness, so has a stimulant action. It can also be a cause of insomnia in some people, and decaffeinated coffee and tea are commonly available.

Coffee beans contain about 1% caffeine, and the beverage contains about 70 mg/100 mL. Tea contains 1.5–2.5% caffeine, about 50–60 mg/100 mL of the beverage. Cola drinks contain 12–18 mg/100 mL, and some energy drinks may contain more.

See also coffee, decaffeinated; theobromine; xanthine.

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"caffeine." A Dictionary of Food and Nutrition. . Encyclopedia.com. 12 Oct. 2018 <http://www.encyclopedia.com>.

"caffeine." A Dictionary of Food and Nutrition. . Encyclopedia.com. (October 12, 2018). http://www.encyclopedia.com/education/dictionaries-thesauruses-pictures-and-press-releases/caffeine

"caffeine." A Dictionary of Food and Nutrition. . Retrieved October 12, 2018 from Encyclopedia.com: http://www.encyclopedia.com/education/dictionaries-thesauruses-pictures-and-press-releases/caffeine

Learn more about citation styles

Citation styles

Encyclopedia.com gives you the ability to cite reference entries and articles according to common styles from the Modern Language Association (MLA), The Chicago Manual of Style, and the American Psychological Association (APA).

Within the “Cite this article” tool, pick a style to see how all available information looks when formatted according to that style. Then, copy and paste the text into your bibliography or works cited list.

Because each style has its own formatting nuances that evolve over time and not all information is available for every reference entry or article, Encyclopedia.com cannot guarantee each citation it generates. Therefore, it’s best to use Encyclopedia.com citations as a starting point before checking the style against your school or publication’s requirements and the most-recent information available at these sites:

Modern Language Association

http://www.mla.org/style

The Chicago Manual of Style

http://www.chicagomanualofstyle.org/tools_citationguide.html

American Psychological Association

http://apastyle.apa.org/

Notes:
  • Most online reference entries and articles do not have page numbers. Therefore, that information is unavailable for most Encyclopedia.com content. However, the date of retrieval is often important. Refer to each style’s convention regarding the best way to format page numbers and retrieval dates.
  • In addition to the MLA, Chicago, and APA styles, your school, university, publication, or institution may have its own requirements for citations. Therefore, be sure to refer to those guidelines when editing your bibliography or works cited list.

caffeine

caffeine (C8H10N4O2) White, bitter substance that occurs in coffee, tea and other substances, such as cocoa and ilex plants. It acts as a mild, harmless stimulant and diuretic, although an excessive dose can cause insomnia and delirium.

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"caffeine." World Encyclopedia. . Encyclopedia.com. 12 Oct. 2018 <http://www.encyclopedia.com>.

"caffeine." World Encyclopedia. . Encyclopedia.com. (October 12, 2018). http://www.encyclopedia.com/environment/encyclopedias-almanacs-transcripts-and-maps/caffeine

"caffeine." World Encyclopedia. . Retrieved October 12, 2018 from Encyclopedia.com: http://www.encyclopedia.com/environment/encyclopedias-almanacs-transcripts-and-maps/caffeine

Learn more about citation styles

Citation styles

Encyclopedia.com gives you the ability to cite reference entries and articles according to common styles from the Modern Language Association (MLA), The Chicago Manual of Style, and the American Psychological Association (APA).

Within the “Cite this article” tool, pick a style to see how all available information looks when formatted according to that style. Then, copy and paste the text into your bibliography or works cited list.

Because each style has its own formatting nuances that evolve over time and not all information is available for every reference entry or article, Encyclopedia.com cannot guarantee each citation it generates. Therefore, it’s best to use Encyclopedia.com citations as a starting point before checking the style against your school or publication’s requirements and the most-recent information available at these sites:

Modern Language Association

http://www.mla.org/style

The Chicago Manual of Style

http://www.chicagomanualofstyle.org/tools_citationguide.html

American Psychological Association

http://apastyle.apa.org/

Notes:
  • Most online reference entries and articles do not have page numbers. Therefore, that information is unavailable for most Encyclopedia.com content. However, the date of retrieval is often important. Refer to each style’s convention regarding the best way to format page numbers and retrieval dates.
  • In addition to the MLA, Chicago, and APA styles, your school, university, publication, or institution may have its own requirements for citations. Therefore, be sure to refer to those guidelines when editing your bibliography or works cited list.

caffeine

caf·feine / kaˈfēn; ˈkafˌēn/ • n. the alkaloid crystalline compound C8H10N4O2, found esp. in tea and coffee plants. It is a stimulant of the central nervous system.

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"caffeine." The Oxford Pocket Dictionary of Current English. . Encyclopedia.com. 12 Oct. 2018 <http://www.encyclopedia.com>.

"caffeine." The Oxford Pocket Dictionary of Current English. . Encyclopedia.com. (October 12, 2018). http://www.encyclopedia.com/humanities/dictionaries-thesauruses-pictures-and-press-releases/caffeine-0

"caffeine." The Oxford Pocket Dictionary of Current English. . Retrieved October 12, 2018 from Encyclopedia.com: http://www.encyclopedia.com/humanities/dictionaries-thesauruses-pictures-and-press-releases/caffeine-0

Learn more about citation styles

Citation styles

Encyclopedia.com gives you the ability to cite reference entries and articles according to common styles from the Modern Language Association (MLA), The Chicago Manual of Style, and the American Psychological Association (APA).

Within the “Cite this article” tool, pick a style to see how all available information looks when formatted according to that style. Then, copy and paste the text into your bibliography or works cited list.

Because each style has its own formatting nuances that evolve over time and not all information is available for every reference entry or article, Encyclopedia.com cannot guarantee each citation it generates. Therefore, it’s best to use Encyclopedia.com citations as a starting point before checking the style against your school or publication’s requirements and the most-recent information available at these sites:

Modern Language Association

http://www.mla.org/style

The Chicago Manual of Style

http://www.chicagomanualofstyle.org/tools_citationguide.html

American Psychological Association

http://apastyle.apa.org/

Notes:
  • Most online reference entries and articles do not have page numbers. Therefore, that information is unavailable for most Encyclopedia.com content. However, the date of retrieval is often important. Refer to each style’s convention regarding the best way to format page numbers and retrieval dates.
  • In addition to the MLA, Chicago, and APA styles, your school, university, publication, or institution may have its own requirements for citations. Therefore, be sure to refer to those guidelines when editing your bibliography or works cited list.

caffeine

caffeine (kaf-een) n. an alkaloid drug, present in coffee and tea, that has a stimulant action on the central nervous system and is a weak diuretic. It is included in some analgesic preparations.

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"caffeine." A Dictionary of Nursing. . Encyclopedia.com. 12 Oct. 2018 <http://www.encyclopedia.com>.

"caffeine." A Dictionary of Nursing. . Encyclopedia.com. (October 12, 2018). http://www.encyclopedia.com/caregiving/dictionaries-thesauruses-pictures-and-press-releases/caffeine

"caffeine." A Dictionary of Nursing. . Retrieved October 12, 2018 from Encyclopedia.com: http://www.encyclopedia.com/caregiving/dictionaries-thesauruses-pictures-and-press-releases/caffeine

Learn more about citation styles

Citation styles

Encyclopedia.com gives you the ability to cite reference entries and articles according to common styles from the Modern Language Association (MLA), The Chicago Manual of Style, and the American Psychological Association (APA).

Within the “Cite this article” tool, pick a style to see how all available information looks when formatted according to that style. Then, copy and paste the text into your bibliography or works cited list.

Because each style has its own formatting nuances that evolve over time and not all information is available for every reference entry or article, Encyclopedia.com cannot guarantee each citation it generates. Therefore, it’s best to use Encyclopedia.com citations as a starting point before checking the style against your school or publication’s requirements and the most-recent information available at these sites:

Modern Language Association

http://www.mla.org/style

The Chicago Manual of Style

http://www.chicagomanualofstyle.org/tools_citationguide.html

American Psychological Association

http://apastyle.apa.org/

Notes:
  • Most online reference entries and articles do not have page numbers. Therefore, that information is unavailable for most Encyclopedia.com content. However, the date of retrieval is often important. Refer to each style’s convention regarding the best way to format page numbers and retrieval dates.
  • In addition to the MLA, Chicago, and APA styles, your school, university, publication, or institution may have its own requirements for citations. Therefore, be sure to refer to those guidelines when editing your bibliography or works cited list.

caffeine

caffeine (chem.) alkaloid found in the coffee and tea plants. XIX. — F. caféine, f. café COFFEE; see -INE 5.

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"caffeine." The Concise Oxford Dictionary of English Etymology. . Encyclopedia.com. 12 Oct. 2018 <http://www.encyclopedia.com>.

"caffeine." The Concise Oxford Dictionary of English Etymology. . Encyclopedia.com. (October 12, 2018). http://www.encyclopedia.com/humanities/dictionaries-thesauruses-pictures-and-press-releases/caffeine-1

"caffeine." The Concise Oxford Dictionary of English Etymology. . Retrieved October 12, 2018 from Encyclopedia.com: http://www.encyclopedia.com/humanities/dictionaries-thesauruses-pictures-and-press-releases/caffeine-1

Learn more about citation styles

Citation styles

Encyclopedia.com gives you the ability to cite reference entries and articles according to common styles from the Modern Language Association (MLA), The Chicago Manual of Style, and the American Psychological Association (APA).

Within the “Cite this article” tool, pick a style to see how all available information looks when formatted according to that style. Then, copy and paste the text into your bibliography or works cited list.

Because each style has its own formatting nuances that evolve over time and not all information is available for every reference entry or article, Encyclopedia.com cannot guarantee each citation it generates. Therefore, it’s best to use Encyclopedia.com citations as a starting point before checking the style against your school or publication’s requirements and the most-recent information available at these sites:

Modern Language Association

http://www.mla.org/style

The Chicago Manual of Style

http://www.chicagomanualofstyle.org/tools_citationguide.html

American Psychological Association

http://apastyle.apa.org/

Notes:
  • Most online reference entries and articles do not have page numbers. Therefore, that information is unavailable for most Encyclopedia.com content. However, the date of retrieval is often important. Refer to each style’s convention regarding the best way to format page numbers and retrieval dates.
  • In addition to the MLA, Chicago, and APA styles, your school, university, publication, or institution may have its own requirements for citations. Therefore, be sure to refer to those guidelines when editing your bibliography or works cited list.

caffeine

caffeine •gradine • sanidine •codeine, Roedean •undine • iodine •Aberdeen, gaberdine •almandine • grenadine • Geraldine •caffeine • Delphine • Josephine •morphine • carrageen • aubergine •indigene • hygiene • phosgene •Eugene • Tolkien • Kathleen •Arlene, Charlene, Darlene, Marlene, praline •Hellene, philhellene •Aileen, Raelene, scalene •spring-clean • crimplene • Abilene •Ghibelline • Cymbeline • terylene •vaseline • acetylene • Mytilene •Eileen • colleen • Pauline •mousseline • Hölderlin • nepheline •Evangeline •Jacqueline, Sakhalin •Emmeline • tourmaline • trampoline •gasoline • naphthalene • Rosaleen •rosaline

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"caffeine." Oxford Dictionary of Rhymes. . Encyclopedia.com. 12 Oct. 2018 <http://www.encyclopedia.com>.

"caffeine." Oxford Dictionary of Rhymes. . Encyclopedia.com. (October 12, 2018). http://www.encyclopedia.com/humanities/dictionaries-thesauruses-pictures-and-press-releases/caffeine

"caffeine." Oxford Dictionary of Rhymes. . Retrieved October 12, 2018 from Encyclopedia.com: http://www.encyclopedia.com/humanities/dictionaries-thesauruses-pictures-and-press-releases/caffeine

Learn more about citation styles

Citation styles

Encyclopedia.com gives you the ability to cite reference entries and articles according to common styles from the Modern Language Association (MLA), The Chicago Manual of Style, and the American Psychological Association (APA).

Within the “Cite this article” tool, pick a style to see how all available information looks when formatted according to that style. Then, copy and paste the text into your bibliography or works cited list.

Because each style has its own formatting nuances that evolve over time and not all information is available for every reference entry or article, Encyclopedia.com cannot guarantee each citation it generates. Therefore, it’s best to use Encyclopedia.com citations as a starting point before checking the style against your school or publication’s requirements and the most-recent information available at these sites:

Modern Language Association

http://www.mla.org/style

The Chicago Manual of Style

http://www.chicagomanualofstyle.org/tools_citationguide.html

American Psychological Association

http://apastyle.apa.org/

Notes:
  • Most online reference entries and articles do not have page numbers. Therefore, that information is unavailable for most Encyclopedia.com content. However, the date of retrieval is often important. Refer to each style’s convention regarding the best way to format page numbers and retrieval dates.
  • In addition to the MLA, Chicago, and APA styles, your school, university, publication, or institution may have its own requirements for citations. Therefore, be sure to refer to those guidelines when editing your bibliography or works cited list.

Caffeine

Caffeine

Description

Caffeine is a drug that stimulates the central nervous system (CNS). Caffeine is found naturally in coffee, kola seed kernels or nuts (Cola nidtida), and a variety of teas. Other foods and beverages, such as chocolate and soft drinks, also contain caffeine, and the drug can be purchased in over-the-counter tablet and capsule form (No Doz, Overtime, Pep-Back, Quick-Pep, Caffedrine, and Vivarin). Some prescription pain relievers, medicines for migraine headaches, and antihistamines also contain caffeine.

General use

Caffeine makes people more alert, less drowsy, and improves coordination. Combined with certain pain relievers or medicines for treating migraine headache, caffeine makes those drugs work more quickly and effectively. Caffeine alone can also help relieve headaches. Antihistamines are sometimes combined with caffeine to counteract the drowsiness caused by those drugs. Caffeine is also sometimes used to treat other conditions, including breathing problems in newborns and in young babies after surgery.

Preparations

Kola can be prepared in decoction or tincture form. To prepare a decoction, mix 1-2 tsp of powdered kola nut in a cup of water. After bringing the water to a boil, simmer the decoction on low heat for 10-15 minutes. Tinctures of kola nut can be purchased at many health food stores or mail order suppliers. A tincture is an herbal preparation made by diluting the herb in alcohol, glycerin, or vinegar. Dosage of kola tincture varies by formula and the symptoms or illness it is supposed to treat, but an average recommended dosage might be 1-4 ml three times daily. Powdered kola nut and kola tinctures should be stored in airtight containers away from direct light to maintain potency.

For over-the-counter caffeine preparations, adults and children age 12 years and older should take 100-200 mg no more than every three to four hours. In timed-release form, the dose is 200-250 mg once a day. Timed-release forms should not be taken less than six hours before bedtime. Caffeine pills or tablets are typically not recommended for children under 12 years of age.

Precautions

If caffeine is administered in a kola preparation, kola should always be obtained from a reputable source that observes stringent quality control procedures and industry-accepted good manufacturing practices. Consumers should look for the designations "U.S.P." (U.S. Pharmacopeia) or "NF" (National Formulary) on kola nut labeling. Herbal preparations prepared under USP or NF guidelines meet nationally recognized strength, quality, purity, packaging, and labeling standards as recommended by the United States Food and Drug Administration (FDA).

Avoid taking too much caffeine when it is being taken as an over-the-counter drug. Consider how much caffeine is being taken in from coffee, tea, chocolate, soft drinks, and other foods that contain caffeine. Check with a pharmacist or healthcare professional to find out how much caffeine is safe to use.

Caffeine cannot replace sleep and should not be used regularly to stay awake as the drug can lead to more serious sleep disorders, like insomnia.

People who use large amounts of caffeine over long periods build up a tolerance to it. When that happens, they have to use more and more caffeine to get the same effects. Heavy caffeine use can also lead to dependence. If an individual stops using caffeine abruptly, withdrawal symptoms may occur, including headache, fatigue, drowsiness, yawning, irritability, restlessness, vomiting, or runny nose. These symptoms can go on for long as a week.

If taken too close to bedtime, caffeine can interfere with sleep. Even if it does not prevent a person from falling asleep, it may disturb sleep during the night.

The notion that caffeine helps people sober up after drinking too much alcohol is a myth. In fact, using caffeine and alcohol together is not a good idea. The combination can lead to an upset stomach, nausea, and vomiting.

Older people may be more sensitive to caffeine and thus more likely to have certain side effects, such as irritability, nervousness, anxiety, and sleep problems.

Allergies

Anyone with allergies to foods, dyes, preservatives, or to the compounds aminophylline, dyphylline, oxtriphylline, theobromine, or theophylline should check with a physician before using caffeine. Anyone who has ever had an unusual reaction to caffeine should also check with a physician before using it again.

Pregnancy

Caffeine can pass from a pregnant woman's body into the developing fetus. Although there is no evidence that caffeine causes birth defects in people, it does cause such effects in laboratory animals given very large doses (equal to human doses of 12-24 cups of coffee a day). In humans, evidence exists that doses of more than 300 mg of caffeine a day (about the amount of caffeine in two or three cups of coffee) may cause miscarriage or problems with the baby's heart rhythm. Women who take more than 300 mg of caffeine a day during pregnancy are also more likely to have babies with low birth weights. Any woman who is pregnant or planning to become pregnant should check with her physician before using caffeine.

Breastfeeding

Caffeine passes into breast milk and can affect the nursing baby. Nursing babies whose mothers use 600 mg or more of caffeine a day may be irritable and have trouble sleeping. Women who are breastfeeding should check with their physicians before using caffeine.

Other medical conditions

Caffeine may cause problems for people with these medical conditions:

  • peptic ulcer
  • heart arrhythmias or palpitations
  • heart disease or recent heart attack (within a few weeks)
  • high blood pressure
  • liver disease
  • insomnia (trouble sleeping)
  • anxiety or panic attacks
  • agoraphobia (fear of being in open places)
  • premenstrual syndrome (PMS)

Side effects

At recommended doses, caffeine can cause restlessness, irritability, nervousness, shakiness, headache, lightheadedness, sleeplessness, nausea, vomiting, and upset stomach. At higher than recommended doses, caffeine can cause excitement, agitation, anxiety, confusion, a sensation of light flashing before the eyes, unusual sensitivity to touch, unusual sensitivity of other senses, ringing in the ears, frequent urination, muscle twitches or tremors, heart arrhythmias, rapid heartbeat, flushing, and convulsions.

Interactions

Using caffeine with certain other drugs may interfere with the effects of the drugs or cause unwanted—and possibly serious—side effects. Certain drugs interfere with the breakdown of caffeine in the body. These include oral contraceptives that contain estrogen, the antiarrhythmia drug mexiletine (Mexitil), the ulcer drug cimetidine (Tagamet), and the drug disulfiram (Antabuse), used to treat alcoholism.

Caffeine interferes with drugs that regulate heart rhythm, such as quinidine and propranolol (Inderal). Caffeine may also interfere with the body's absorption of iron. Anyone who takes iron supplements should take them at least an hour before or two hours after using caffeine.

Serious side effects are possible when caffeine is combined with certain drugs. For example, taking caffeine with the decongestant phenylpropanolamine can raise blood pressure. Very serious heart problems may occur if caffeine and monoamine oxidase inhibitors (MAO) are taken together. These drugs are used to treat Parkinson's disease, depression, and other psychiatric conditions. Consult with a pharmacist or physician about which drugs can interact with caffeine.

Because caffeine stimulates the nervous system, anyone taking other central nervous system stimulants should be careful about using caffeine.

KEY TERMS

Arrhythmia— Abnormal heart rhythm.

Central nervous system (CNS)— The brain, spinal cord, and nerves throughout the body.

Decoction— An herbal extract produced by mixing an herb in cold water, bringing the mixture to a boil, and letting it simmer to evaporate the excess water. The decoction is then strained and drank hot or cold. Decoctions are usually chosen over infusion when the botanical or herb in question is a root, seed, or berry.

Palpitation— Rapid, forceful, throbbing, or fluttering heartbeat.

Tinctures— A liquid extract of an herb prepared by steeping the herb in an alcohol and water mixture. Tinctures can also be prepared using vinegar or glycerin, instead of alcohol.

Withdrawal symptoms— A group of physical or mental symptoms that may occur when a person suddenly stops using a drug to which he or she has become dependent.

Resources

BOOKS

Hoffman, David. The Complete Illustrated Herbal. New York: Barnes & Noble Books, 1999.

Medical Economics Corporation. The PDR for Herbal Medicines. Montvale, NJ: Medical Economics Corporation, 1998.

ORGANIZATIONS

Office of Dietary Supplements. National Institutes of Health. Building 31, Room 1B25, 31 Center Drive, MSC 2086, Bethesda, MD 20892-2086. (301) 435-2920. Fax: (301) 480-1845. 〈http://odp.od.nih.gov/ods/〉 (Includes on-line access to International Bibliographic Information on Dietary Supplements (IBIDS), a database of published, international scientific literature on dietary supplements and botanicals).

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"Caffeine." Gale Encyclopedia of Nursing and Allied Health. . Encyclopedia.com. 12 Oct. 2018 <http://www.encyclopedia.com>.

"Caffeine." Gale Encyclopedia of Nursing and Allied Health. . Encyclopedia.com. (October 12, 2018). http://www.encyclopedia.com/medicine/encyclopedias-almanacs-transcripts-and-maps/caffeine-3

"Caffeine." Gale Encyclopedia of Nursing and Allied Health. . Retrieved October 12, 2018 from Encyclopedia.com: http://www.encyclopedia.com/medicine/encyclopedias-almanacs-transcripts-and-maps/caffeine-3

Learn more about citation styles

Citation styles

Encyclopedia.com gives you the ability to cite reference entries and articles according to common styles from the Modern Language Association (MLA), The Chicago Manual of Style, and the American Psychological Association (APA).

Within the “Cite this article” tool, pick a style to see how all available information looks when formatted according to that style. Then, copy and paste the text into your bibliography or works cited list.

Because each style has its own formatting nuances that evolve over time and not all information is available for every reference entry or article, Encyclopedia.com cannot guarantee each citation it generates. Therefore, it’s best to use Encyclopedia.com citations as a starting point before checking the style against your school or publication’s requirements and the most-recent information available at these sites:

Modern Language Association

http://www.mla.org/style

The Chicago Manual of Style

http://www.chicagomanualofstyle.org/tools_citationguide.html

American Psychological Association

http://apastyle.apa.org/

Notes:
  • Most online reference entries and articles do not have page numbers. Therefore, that information is unavailable for most Encyclopedia.com content. However, the date of retrieval is often important. Refer to each style’s convention regarding the best way to format page numbers and retrieval dates.
  • In addition to the MLA, Chicago, and APA styles, your school, university, publication, or institution may have its own requirements for citations. Therefore, be sure to refer to those guidelines when editing your bibliography or works cited list.

Caffeine

Caffeine

Definition

Purpose

Description

Precautions

Interactions

Complications

Parental concerns

Resources

Definition

Caffeine is a mild alkaloid stimulant made by some plants. It is found in coffee beans, tea leaves, and cocao beans, added to soft drinks, energy drinks, energy bars, and sold in capsules and tablets as a dietary supplement. Caffeine has no nutritional value.

Purpose

Caffeine is a mild stimulant. It is used to temporarily relieve fatigue and increase mental alertness. Caffeine is added to some antihistamine drugs to help counteract the sleepiness they may cause. It is also added to over-the-counter headache remedies (e.g., Excedrin) and migraine headache drugs to enhance their painkilling effects. Under medical supervision, citrated caffeine (a prescription drug) is used to treat breathing problems in premature infants.

Description

Caffeine, from the Italian word cafée, meaning coffee, is naturally made by about 60 plants. The most familiar of these are coffee leaves and beans, tea leaves, kola nuts, yerba mate, guarana berries, and cacao (the source of chocolate). In plants, caffeine is a pesticide. Insects eating plants that contain caffeine become disabled or die.

Humans have eaten plants containing caffeine for thousands of years; first chewing the seeds and leaves,

Caffeine

Product Amount of caffeine(mg)
Cocaine energy drink, 8.5 oz.280
Caffeine tablet, 1200
Coffee, brewed 8 oz.135
Red Bull energy drink, 8.5 oz.80
SoBe No Fear energy drink, 8 oz.80
Excedrin headache tablet, 165
Mountain Dew, 1 can, 12 oz.55
Black tea, brewed, 8 oz.50
Diet Coke, 1 can, 12 oz.45
Sunkist Orange, regular or diet, 1 can, 12 oz.41
Coffee, espresso, 1 oz.40
Pepsi Cola, 1 can, 12 oz.37
Coca-Cola Classic, 1 can, 12 oz.34
Hershey’s Special Dark chocolate, 1 bar, 1.5 oz.31
Barq’s Root Beer, 1 can, 12 oz.22
Green tea, brewed, 8 oz.15
Hershey’s Milk Chocolate, 1 bar, 1.5 oz.10
Coffee, decaffeinated, 8 oz.5
Tea, decaffeinated, 8 oz.4
Diet Barq’s Root Beer, 1 can, 12 oz.0
Sprite, diet or regular, 1 can, 12 oz.0
7-Up, 1 can, 12 oz.0

(Illustration by GGS Information Services/Thomson Gale.)

and later boiling them and drinking the resulting liquid. Coffee, a major source of caffeine, was introduced to Europe from the Middle East in the seventeenth century and rapidly became a popular drink. Coffee houses began appearing in London in the mid-1600s. A German chemist purified caffeine in 1819. Today, besides being found naturally in coffee, tea, and chocolate, it is added to soft drinks, energy drinks and bars, headache remedies, and is sold as a dietary supplement to improve mental and physical functioning. The United States is a highly caffeinated nation. In 2007, it was estimated that 90% of North Americans consumed caffeine daily.

Caffeine is the most widely used psychoactive compound in the world. It has no nutritional value, but has these effects on the body:

  • increases heart rate
  • temporarily increases blood pressure
  • increases urine output (a diuretic)
  • relaxes smooth muscle cells in the airways
  • releases fatty acids and glycerol in the body for energy use
  • easily crosses the blood-brain barrier and changes the level of neurotransmitters in the brain
  • passes into breast milk

Caffeine is absorbed in the stomach. Its effects are noticeable in about 15 minutes and usually last several hours. However, there is huge variation among people both in their sensitivity to caffeine and in how long it stays in their bodies. Although the average time it takes half a dose of caffeine to be eliminated from the body is three to four hours, this time may extend to six hours in women taking oral contraceptives, and be much longer in pregnant women and in people with liver damage.

Many well-designed, well-documented studies show that caffeine makes people more alert, improves short-term memory, enhances the ability to concentrate, increases the individual’s capacity for physical work and speeds up reaction time. However, caffeine achieves this by preventing detrimental effects of withdrawal in habitual caffeine drinkers. It does not boost functioning to above normal levels. All these effects are temporary. Caffeine does not replace the need for rest or sleep.

Caffeine is on the United States Food and Drug Administration (FDA) list of foods generally recognized as safe (GRAS list). In moderate amounts, caffeine does not appear to be harmful to humans, although it is poisonous to dogs, horses, and some birds. “Moderate” generally means consumption in the rage of 300-400 mg or 3-4 cups of coffee daily. Caffeine has not been shown to cause birth defects and is considered safe in reasonable amounts during pregnancy. The March of Dimes Birth Defects Foundation recommends that pregnant women limit their caffeine intake to the equivalent of two cups of coffee per day, and that women who are having difficulty becoming pregnant eliminate caffeine from their diet.

By law, caffeine must be listed as an ingredient on food labels, but the amount of caffeine per serving is not required to be disclosed. Since caffeine is added to so many products, it is difficult to the amount of caffeine in an individual’s diet. Caffeine content of coffees and teas varies depending on where the plants were grown and how the beverages are prepared. The approximate amounts of caffeine is some common products are:

  • coffee, brewed 8 oz: 135 mg
  • coffee, decaffeinated, 8 oz: 5 mg
  • coffee, espresso, 1 oz: 40 mg
  • green tea, brewed, 8 oz: 15 mg
  • black tea, brewed, 8 oz: 50 mg
  • tea, decaffeinated, 8 oz: 4 mg
  • Mountain Dew, 1 can (12 oz): 55 mg
  • Coca-Cola Classic, 1 can (12 oz): 34 mg
  • Diet Coke: 1 can (12 oz) 45 mg
  • Pepsi Cola, 1 can (12 oz): 37 mg
  • Sunkist Orange, regular or diet, 1 can (12 oz): 41 mg
  • Barq’s Root Beer: 1 can (12 oz): 22 mg
  • diet Barq’s Root Beer: 1 can (12 oz): 0 mg
  • Sprite, diet or regular: 1 can (12 oz) 0 mg
  • 7-Up, 1 can (12 ounces): 0 mg
  • Red Bull energy drink, 8.5 oz: 80 mg
  • Cocaine energy drink, 8.5 oz: 280 mg
  • SoBe No Fear energy drink, 8 oz: 80 mg
  • Hershey’s Special Dark chocolate, 1 bar (1.5 oz): 31 mg
  • Hershey’s Milk Chocolate, 1 bar (1.5 oz): 10 mg
  • Excedrin headache tablet, 1: 65 mg
  • caffeine tablet, 1: 200 mg

Precautions

People vary in their sensitivity to caffeine based on their weight, age, medications they may be taking, and personal biology. Individuals should be alert to how much caffeine they consume during a day and how it makes them feel, then moderate their intake accordingly. Caffeine does not replace the need for sleep. All mental and physical benefits are temporary and a “crash” is likely to occur after a dose of caffeine wears off. People who use caffeine to stay awake to drive or operate heavy machinery are at risk of being involved in an accident because of excessive tiredness once the effect of caffeine wears off.

Caffeine stays in the system of pregnant women and people with liver damage longer than normal. These people should closely monitor their caffeine intake.

Caffeine passes into breast milk and although it may have no effect on the breastfeeding woman, it may make the infant restless, irritable, and less likely to sleep.

Athletes should be aware that the International Olympic Committee tests for caffeine levels over 12 mg/ml of urine. This level could be reached by drinking four large cups of coffee.

Interactions

Caffeine appears to enhance the effectiveness of over-the-counter headache remedies. Some of these medications contain a mixture of caffeine and painkiller. People with a high sensitivity to caffeine should read the labels carefully.

People taking diuretic medication (water pills) may see increased urine output because caffeine is a weak diuretic.

Complications

Although caffeine in moderate amounts poses no major health risks, the body quickly develops tolerance to the effects of caffeine, along with a mild physical and psychological dependency. For example, tolerance to caffeine-related sleep disruption disappears in about a week among people who drink 3–4 cups of coffee daily. The amount of caffeine it takes to reach this state is highly variable.

Discontinuing caffeine among regular users causes withdrawal symptoms. These can include headaches (very common), irritability, nausea, fatigue, sleepiness, inability to concentrate, and mild depression. Caffeine withdrawal symptoms begin 12-24 hours after caffeine is stopped. Withdrawal symptoms peak at around 48 hours, and can last up to five days. Tapering caffeine use, for example cutting down on caffeine by the equivalent of half a cup of coffee (about 50 mg) a day, minimizes or eliminates withdrawal symptoms.

People who use more than about 500 mg (the amount varies greatly among individuals) of caffeine a day may develop a condition called caffeinism. Caf-feinism produces unpleasant sensations, some of which are similar to withdrawal symptoms. Symptoms caffeine overuse include restlessness, irritability, nervousness, anxiety, muscle twitching, headaches, inability to fall asleep, and a racing heart. Severe overuse of caffeine can cause four psychiatric disorders recognized by the American Psychiatric Association and described in the Diagnostic and Statistical Manual of Mental Disorders, Fourth EditionCaffeine is considered the cause of these disorders after other causes have been ruled out.

  • Caffeine intoxication: Usually the result of taking caffeine pills (e.g., NoDoz), this condition causes mental changes, rambling thoughts and speech, irregular heart beat, and all symptoms associated with overuse. In severe cases death can result from ventricular fibrillation (unsynchronized contractions of the ventricle of the heart).
  • Caffeine-induced anxiety disorder: Severe anxiety that interferes with daily social interactions and occurs after caffeine intoxication or heavy long-term use of caffeine.
  • Caffeine-induced sleep disorder: An inability to sleep that is so great it requires medical/psychiatric attention and occurs after prolonged caffeine consumption.
  • Non-specific caffeine-induced disorder: Disorders not listed that are attributable to either acute or long-term caffeine consumption.

Parental concerns

Children get most of their caffeine from soft drinks. Parents should choose soft drinks that contain little or no caffeine or replace soft drinks with water,

KEY TERMS

Alkaloid— An organic, compound found in plants; chemically it is a base and usually contains at least one nitrogen atom.

Blood-brain barrier— A specialized, semi-permeable layer of cells around the blood vessels in the brain that controls which substances can leave the circulatory system and enter the brain.

Neurotransmitter— One of a group of chemicals secreted by a nerve cell (neuron) to carry a chemical message to another nerve cell, often as a way of transmitting a nerve impulse. Examples of neuro-transmitters include acetylcholine, dopamine, serotonin, and norepinephrine.

Tolerance— Adjustment of the body to a drug so that it takes more and more to produce the same physiological or psychological effect, or adjustment to a drug so that side effects are diminished.

fruit juice, or low-fat milk. Adolescents are increasingly using energy drinks and energy bars containing caffeine. At the same time, many adolescents start drinking coffee. Parents educate their children about the effects of caffeine and encourage them to monitor their caffeine consumption from all sources.

Accidental overdose from caffeine pills can be fatal. Caffeine tablets, like all drugs, should be kept out of reach of children. Children who accidentally eat caffeine pills need immediate medical attention from a physician or emergency room.

Resources

BOOKS

Klosterman, Lorrie. The Facts About Caffeine. New York:Marshall Cavendish Benchmark, 2006.

Mumaw, Stefan, and Wendy Lee Oldfield. Caffeine for the Creative Mind: 250 Exercises to Wake Up Your Brain. Cincinnati, OH: HOW Books, 2006.

Smith, Barry D., Uma Gupta, and B.S. Gupta, eds. Caffeine and Activation Theory: Effects on Health and Behavior. Boca Raton, FL: CRC Press, 2007.

Weinberg, Bennett Alan, and Bonnie K. Bealer. The World of Caffeine: The Science and Culture of the World’s Most Popular Drug. New York: Routledge, 2001.

ORGANIZATIONS

American Heart Association. 7272 Greenville Avenue, Dallas, TX 75231. Telephone: (800) 242-8721. Website: <http://www.americanheart.org>.

Food Standards Agency, Aviation House. 125 Kingsway, London, UK WC2B 6NH Telephone: 020 7276 8000. Website: <http://www.eatwell.gov.uk>

International Food Information Council. 1100 Connecticut Avenue, NW Suite 430, Washington, DC 20036. Telephone: 202-296-6540. Fax: 202-296-6547. Website: <http://ific.org>.

OTHER

Chawla, Jasvinder, and Amer Suleman. “Neurologic Effects of Caffeine.” emedicine.com. June 7, 2006. [cited April 30, 2007].<http://www.emedicine.com/neuro/topic666.htm>.

Doheny, Kathleen. “Pros and Cons of the Caffeine Craze.” WebMD.com. October 17, 2006. [April 30, 2007]. <http://www.webmd.com/diet/features/pros-and-cons-caffeine-craze>

Lande, R. Gregory. “Caffeine-related Psychiatric Disorders.” emedicine.com. July 7, 2005. [cited April 30, 2007]. <http://www.emedicine.com/med/topic3115.htm>

March of Dimes Birth Defects Foundation. “Caffeine in Pregnancy.” marchofdimes.com. 2007. [April 30, 2007]. <http://search.marchofdimes.com/>.

Mayo Clinic Staff. “Caffeine Content of Common Beverages.” MayoClinic.com. October 3, 2005. [cited April 30, 2007]. <http://www.mayoclinic.com/health/caf-feine/AN01211>.

Mayo Clinic Staff. “The Caffeine Question: Should You Decaffeinate Your Diet?” MayoClinic.com. March 8, 2007. [cited April 30, 2007]. <http://www.mayoclinic.-com/health/caffeine/NU00600>.

Tish Davidson, A.M.

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"Caffeine." The Gale Encyclopedia of Diets: A Guide to Health and Nutrition. . Encyclopedia.com. 12 Oct. 2018 <http://www.encyclopedia.com>.

"Caffeine." The Gale Encyclopedia of Diets: A Guide to Health and Nutrition. . Encyclopedia.com. (October 12, 2018). http://www.encyclopedia.com/science/encyclopedias-almanacs-transcripts-and-maps/caffeine

"Caffeine." The Gale Encyclopedia of Diets: A Guide to Health and Nutrition. . Retrieved October 12, 2018 from Encyclopedia.com: http://www.encyclopedia.com/science/encyclopedias-almanacs-transcripts-and-maps/caffeine

Learn more about citation styles

Citation styles

Encyclopedia.com gives you the ability to cite reference entries and articles according to common styles from the Modern Language Association (MLA), The Chicago Manual of Style, and the American Psychological Association (APA).

Within the “Cite this article” tool, pick a style to see how all available information looks when formatted according to that style. Then, copy and paste the text into your bibliography or works cited list.

Because each style has its own formatting nuances that evolve over time and not all information is available for every reference entry or article, Encyclopedia.com cannot guarantee each citation it generates. Therefore, it’s best to use Encyclopedia.com citations as a starting point before checking the style against your school or publication’s requirements and the most-recent information available at these sites:

Modern Language Association

http://www.mla.org/style

The Chicago Manual of Style

http://www.chicagomanualofstyle.org/tools_citationguide.html

American Psychological Association

http://apastyle.apa.org/

Notes:
  • Most online reference entries and articles do not have page numbers. Therefore, that information is unavailable for most Encyclopedia.com content. However, the date of retrieval is often important. Refer to each style’s convention regarding the best way to format page numbers and retrieval dates.
  • In addition to the MLA, Chicago, and APA styles, your school, university, publication, or institution may have its own requirements for citations. Therefore, be sure to refer to those guidelines when editing your bibliography or works cited list.

Caffeine

Caffeine

Chemistry of caffeine

History

Sources

Pharmacological effects

Teratogenic and mutagenic effects

Usage, tolerance, and Interactions

Resources

Caffeine, scientific name methylxanthine, is an alkaloid found in coffee, tea, chocolate, and other natural foods. It is also a component of cola soft drinks. Caffeine has been a part of the human diet for many centuries and is one of the most widely used central nervous system stimulants worldwide. In recent years, research has raised questions about possible deleterious health effects of caffeine, but no definitive conclusions have been reached about the harmfulness of moderate amounts.

Chemistry of caffeine

Caffeines chemical name is 3,7-dihydro-1,3,7-trimethyl-1H-purine-2, 6-dione. It is also known as theine, methyl theobromine, and 1,3,7-trimethylxanthine. Its molecular formula is C8 H10 N4 O2H2 O, and it consists of bicyclic molecules derived from the purine ring system.

In its pure form, caffeine is a fleecy white solid or long silky crystals. It is odorless, but has a distinctive bitter taste. When heated, caffeine loses water at 176°F (80°C), sublimes at 352.4°F (178°C), and/or melts at 458.2°F (236.8°C). It is only slightly soluble in water and alcohol, but dissolves readily in chloroform. Water solutions of caffeine are essentially neutral (pH = 6.9).

Caffeine is a member of the alkaloid family, a group of compounds obtained from plants whose molecules consist of nitrogen-containing rings. In general, alkaloids tend to have identifiable physiological effects on the human body, although these effects vary greatly from compound to compound.

History

The use of caffeine is thought to go back as far as the Stone Age, which began about 2.5 million years ago and ended in some parts of the world only about 5,000 years ago. It would probably be safe to say that caffeine was a regular part of the human diet for thousands of years. Although the pleasures of coffee, have been known to humans for centuries, the isolation of caffeine from these beverages was accomplished only in the early 1800s. During the 1820s, researchers identified the active agents in tea and chocolate and gave them a variety of names such as guaranin. In 1840, T. Martins and D. Berthemot independently showed that these compounds are all identical with caffeine. Caffeine itself was originally called cofeine or caffein and only in the late 1820s was given the name by which it is known today.

Much of the work leading to the full characterization of caffeines molecular structure was completed by German chemist Emil Fischer (18521919). Fischer first synthesized the compound from raw materials in 1895, and two years later derived its precise structural formula.

Sources

Of all the commercial sources of caffeine, guarana paste has the highest concentration of the pure compound, about 4%. Guarana paste is made from the seed of the Paullinia tree, found primarily in Brazil. More common sources of caffeine contain lower concentrations of the compound: 1.1 to 2.2% in coffee beans; 3.5% in tea leaves; and 1.5% in kola nuts. Other less common sources of caffeine include mate´ leaves, obtained from the Ilex plant (less than 0.7% caffeine), and yoco bark, obtained from the Paullinia yoco tree (2.7% caffeine).

Because of the way in which these foods are prepared, the above data do not give an accurate picture of the amount of caffeine that people consume. The average cup coffee, for example, contains approximately 100 to 150 mg of caffeine; the average cup of tea, 50 mg of caffeine; and the average cup of cocoa, about 5 mg of caffeine. Cola drinks tend to contain 35 to 55 mg of caffeine, and the average chocolate bar contains about 20 mg of the compound. Beginning in 1997 and continuing into the 2000s, products are increasingly introduced that contain caffeine including bottled water and chewing gum.

Pharmacological effects

The most important physiological effect of caffeine is that it stimulates nerve cells, particularly those in the brain. It appears that caffeine molecules bind to neurotransmitter receptor sites in nerve cells, causing the continual stimulation of those cells. This property explains the most common clinical symptoms of caffeine ingestion: wakefulness, excitability, increased mental awareness, and restlessness.

Caffeine affects nerve tissue in the brain much more quickly than it does nerve tissue anywhere else in the body. As a result, it will bring about muscular changes such as convulsions only with very high doses of the drug10 g or more, the equivalent of drinking 70 to 100 cups of coffee in a short time. Death from caffeine overdose is, therefore, extremely unlikely.

Teratogenic and mutagenic effects

Concerns about the possible health effects of consuming caffeine have been expressed for well over a hundred years. Recent concern about its physiological effects tends to focus on mutagenic and teratogenic effects. Mutagenic effects are those that change the reproductive genes, producing mutations in subsequent generations. Scientific reports have also appeared connecting the consumption of large doses of caffeine with particular types of cancer. However, the significance of such findings to the average coffee or tea drinker is unclear.

The situation with teratogenic effectsthose that affect the fetus while it is still in the wombis somewhat clearer. Caffeine passes readily across the placental lining, exposing the fetus to concentrations of the stimulant that are comparable to those in the mothers blood. Since the developing nervous system of the fetus is more likely to be affected by the drug than is the mothers, a reduction in caffeine intake is often recommended for pregnant women.

Usage, tolerance, and Interactions

People who use large amounts of caffeine over long periods of time build up a tolerance to it. When that happens, they have to use additional caffeine to receive the same effects. Heavy caffeine use can also lead to dependence. Thus, if the person stops using caffeine abruptly, withdrawal symptoms may occur. These symptoms can include throbbing headaches, fatigue, drowsiness, yawning, irritability, restlessness, vomiting, or runny nose. These symptoms can persist for as long as one week if caffeine is avoided. Then the symptoms usually disappear.

Caffeine cannot replace sleep and should not be used regularly to stay awake as the drug can lead to more serious sleep disorders, like insomnia. When determining caffeine dosage, consider how much caffeine is being consumed from all sources such as coffee, tea, chocolate, soft drinks, and other foods and drinks. Check with a pharmacist or physician to find out how much caffeine is safe to use.

Caffeine may cause problems for people with the following medical conditions: food or drug allergies, peptic ulcer, heart arrhythmias or palpitations, heart disease or recent heart attack, high blood pressure, liver disease, insomnia (trouble sleeping), anxiety or panic attacks, agoraphobia (fear of being in open places), and premenstrual syndrome (PMS).

KEY TERMS

Mutagenic Any substance or form of energy that can bring about changes in DNA molecules, thereby leading to changes in an organisms genetic make-up.

Pharmacological Having to do with the properties, uses, and effects of drugs.

Teratogenic Any substance that can bring about changes in a fetus prior to birth.

At recommended doses, caffeine can sometimes cause restlessness, irritability, nervousness, shakiness, headache, lightheadedness, sleeplessness, nausea, vomiting, and upset stomach. At higher than recommended doses, caffeine can cause excitement, agitation, anxiety, confusion, a sensation of light flashing before the eyes, unusual sensitivity to touch, unusual sensitivity of other senses, ringing in the ears, frequent urination, muscle twitches or tremors, heart arrhythmias, rapid heartbeat, flushing, and convulsions.

Certain drugs interfere with the breakdown of caffeine in the body. These include oral contraceptives that contain estrogen, the antiarrhythmia drug mexiletine (Mexitil®), the ulcer drug cimetidine (Tagamet®), and the drug disulfiram (Antabuse®), used to treat alcoholism. Caffeine may also interfere with the bodys absorption of iron. Anyone who takes iron supplements should take them at least an hour before or two hours after using caffeine.

Resources

BOOKS

Banks, Mary. The World Encyclopedia of Coffee. London, UK: Lorenz, 2002.

Cowan, Brian William. The Social Life of Coffee: The Emergence of the British Coffeehouse. New Haven, CT: Yale University Press, 2005.

Dews, Peter B., ed. Caffeine: Perspectives from Research. Berlin, Germany: Springer-Verlag, 1984.

Weinberg, Bennett Alan. The World of Caffeine: The Science and Culture of the Worlds Most Popular Drug. New York: Routledge, 2001.

Wild, Antony. Coffee: A Dark History. New York: W.W. Norton, 2005.

David E. Newton

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"Caffeine." The Gale Encyclopedia of Science. . Encyclopedia.com. 12 Oct. 2018 <http://www.encyclopedia.com>.

"Caffeine." The Gale Encyclopedia of Science. . Encyclopedia.com. (October 12, 2018). http://www.encyclopedia.com/science/encyclopedias-almanacs-transcripts-and-maps/caffeine-0

"Caffeine." The Gale Encyclopedia of Science. . Retrieved October 12, 2018 from Encyclopedia.com: http://www.encyclopedia.com/science/encyclopedias-almanacs-transcripts-and-maps/caffeine-0

Learn more about citation styles

Citation styles

Encyclopedia.com gives you the ability to cite reference entries and articles according to common styles from the Modern Language Association (MLA), The Chicago Manual of Style, and the American Psychological Association (APA).

Within the “Cite this article” tool, pick a style to see how all available information looks when formatted according to that style. Then, copy and paste the text into your bibliography or works cited list.

Because each style has its own formatting nuances that evolve over time and not all information is available for every reference entry or article, Encyclopedia.com cannot guarantee each citation it generates. Therefore, it’s best to use Encyclopedia.com citations as a starting point before checking the style against your school or publication’s requirements and the most-recent information available at these sites:

Modern Language Association

http://www.mla.org/style

The Chicago Manual of Style

http://www.chicagomanualofstyle.org/tools_citationguide.html

American Psychological Association

http://apastyle.apa.org/

Notes:
  • Most online reference entries and articles do not have page numbers. Therefore, that information is unavailable for most Encyclopedia.com content. However, the date of retrieval is often important. Refer to each style’s convention regarding the best way to format page numbers and retrieval dates.
  • In addition to the MLA, Chicago, and APA styles, your school, university, publication, or institution may have its own requirements for citations. Therefore, be sure to refer to those guidelines when editing your bibliography or works cited list.

Caffeine

Caffeine

Description

Caffeine is a drug that stimulates the central nervous system (CNS). Caffeine is found naturally in coffee, kola seed kernels or nuts (Cola nidtida), and a variety of teas. Other foods and beverages, such as chocolate and soft drinks, also contain caffeine, and the drug can be purchased in over-the-counter tablet and capsule form (No Doz, Overtime, Pep-Back, Quick-Pep, Caffedrine, and Vivarin). Some prescription pain relievers, medicines for migraine headaches , and antihistamines also contain caffeine.

General use

Caffeine makes people more alert, less drowsy, and improves coordination. Combined with certain pain relievers or medicines for treating migraine headache, caffeine makes those drugs work more quickly and effectively. Caffeine alone can also help relieve headaches. Antihistamines are sometimes combined with caffeine to counteract the drowsiness caused by those drugs. Caffeine is also sometimes used to treat other conditions, including breathing problems in newborns and in young babies after surgery.

Preparations

Kola can be prepared in decoction or tincture form. To prepare a decoction, mix 1-2 tsp of powdered kola nut in a cup of water. After bringing the water to a boil, simmer the decoction on low heat for 10–15 minutes. Tinctures of kola nut can be purchased at many health food stores or mail order suppliers. A tincture is an herbal preparation made by diluting the herb in alcohol, glycerin, or vinegar. Dosage of kola tincture varies by formula and the symptoms or illness it is supposed to treat, but an average recommended dosage might be 1–4 ml three times daily. Powdered kola nut and kola tinctures should be stored in airtight containers away from direct light to maintain potency.

For over-the-counter caffeine preparations, adults and children age 12 years and older should take 100–200 mg no more than every three to four hours. In timed-release form, the dose is 200–250 mg once a day. Timed-release forms should not be taken less than six hours before bedtime. Caffeine pills or tablets are typically not recommended for children under 12 years of age.

Precautions

If caffeine is administered in a kola preparation, kola should always be obtained from a reputable source that observes stringent quality control procedures and industry-accepted good manufacturing practices. Consumers should look for the designations “U.S.P.” (U.S. Pharmacopeia) or “NF” (National Formulary) on kola nut labeling. Herbal preparations prepared under USP or NF guidelines meet nationally recognized strength, quality, purity, packaging, and labeling standards as recommended by the United States Food and Drug Administration (FDA).

Avoid taking too much caffeine when it is being taken as an over-the-counter drug. Consider how much caffeine is being taken in from coffee, tea, chocolate, soft drinks, and other foods that contain caffeine. Check with a pharmacist or healthcare professional to find out how much caffeine is safe to use.

Caffeine cannot replace sleep and should not be used regularly to stay awake as the drug can lead to more serious sleep disorders , like insomnia .

People who use large amounts of caffeine over long periods build up a tolerance to it. When that happens, they have to use more and more caffeine to get the same effects. Heavy caffeine use can also lead to dependence. If an individual stops using caffeine abruptly, withdrawal symptoms may occur, including headache, fatigue, drowsiness, yawning, irritability, restlessness, vomiting, or runny nose. These symptoms can go on for long as a week.

If taken too close to bedtime, caffeine can interfere with sleep. Even if it does not prevent a person from falling asleep, it may disturb sleep during the night.

The notion that caffeine helps people sober up after drinking too much alcohol is a myth. In fact, using caffeine and alcohol together is not a good idea. The combination can lead to an upset stomach, nausea, and vomiting.

Older people may be more sensitive to caffeine and thus more likely to have certain side effects, such as irritability, nervousness, anxiety , and sleep problems.

Allergies

Anyone with allergies to foods, dyes, preservatives, or to the compounds aminophylline, dyphylline, oxtriphylline, theobromine, or theophylline should check with a physician before using caffeine. Anyone who has ever had an unusual reaction to caffeine should also check with a physician before using it again.

Other medical conditions

Caffeine may cause problems for people with these medical conditions:

Side effects

At recommended doses, caffeine can cause restlessness, irritability, nervousness, shakiness, headache, lightheadedness, sleeplessness, nausea, vomiting, and upset stomach. At higher than recommended doses, caffeine can cause excitement, agitation, anxiety, confusion, a sensation of light flashing before the eyes, unusual sensitivity to touch, unusual sensitivity of other senses, ringing in the ears, frequent urination, muscle twitches or tremors, heart arrhythmias , rapid heartbeat, flushing, and convulsions.

KEY TERMS

Arrhythmia —Abnormal heart rhythm.

Central nervous system (CNS) —The brain, spinal cord, and nerves throughout the body.

Decoction —An herbal extract produced by mixing an herb in cold water, bringing the mixture to a boil, and letting it simmer to evaporate the excess water. The decoction is then strained and drank hot or cold. Decoctions are usually chosen over infusion when the botanical or herb in question is a root, seed, or berry.

Palpitation —Rapid, forceful, throbbing, or fluttering heartbeat.

Tinctures —A liquid extract of an herb prepared by steeping the herb in an alcohol and water mixture. Tinctures can also be prepared using vinegar or glycerin, instead of alcohol.

Withdrawal symptoms —A group of physical or mental symptoms that may occur when a person suddenly stops using a drug to which he or she has become dependent.

Interactions

Using caffeine with certain other drugs may interfere with the effects of the drugs or cause unwanted—and possibly serious—side effects. Certain drugs interfere with the breakdown of caffeine in the body. These include oral contraceptives that contain estrogen, the antiarrhythmia drug mexiletine (Mexitil), the ulcer drug cimetidine (Tagamet), and the drug disulfiram (Antabuse), used to treat alcoholism.

Caffeine interferes with drugs that regulate heart rhythm, such as quinidine and propranolol (Inderal). Caffeine may also interfere with the body's absorption of iron. Anyone who takes iron supplements should take them at least an hour before or two hours after using caffeine.

Serious side effects are possible when caffeine is combined with certain drugs. For example, taking caffeine with the decongestant phenylpropanolamine can raise blood pressure . Very serious heart problems may occur if caffeine and monoamine oxidase inhibitors (MAOIs) are taken together. These drugs are used to treat Parkinson's disease, depression , and other psychiatric conditions. Consult with a pharmacist or physician about which drugs can interact with caffeine.

Because caffeine stimulates the nervous system, anyone taking other central nervous system stimulants should be careful about using caffeine.

Resources

BOOKS

Hoffman, David. The Complete Illustrated Herbal. New York: Barnes & Noble Books, 1999.

Medical Economics Corporation. The PDR for Herbal Medicines. Montvale, NJ: Medical Economics Corporation, 1998.

ORGANIZATIONS

Office of Dietary Supplements. National Institutes of Health. Building 31, Room 1B25, 31 Center Drive, MSC 2086, Bethesda, MD 20892-2086. (301) 435-2920. Fax: (301) 480-1845. http://odp.od.nih.gov/ods/ (Includes on-line access to International Bibliographic Information on Dietary Supplements (IBIDS), a database of published, international scientific literature on dietary supplements and botanicals).

Paula Ford-Martin

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"Caffeine." The Gale Encyclopedia of Senior Health: A Guide for Seniors and Their Caregivers. . Encyclopedia.com. 12 Oct. 2018 <http://www.encyclopedia.com>.

"Caffeine." The Gale Encyclopedia of Senior Health: A Guide for Seniors and Their Caregivers. . Encyclopedia.com. (October 12, 2018). http://www.encyclopedia.com/caregiving/encyclopedias-almanacs-transcripts-and-maps/caffeine

"Caffeine." The Gale Encyclopedia of Senior Health: A Guide for Seniors and Their Caregivers. . Retrieved October 12, 2018 from Encyclopedia.com: http://www.encyclopedia.com/caregiving/encyclopedias-almanacs-transcripts-and-maps/caffeine

Learn more about citation styles

Citation styles

Encyclopedia.com gives you the ability to cite reference entries and articles according to common styles from the Modern Language Association (MLA), The Chicago Manual of Style, and the American Psychological Association (APA).

Within the “Cite this article” tool, pick a style to see how all available information looks when formatted according to that style. Then, copy and paste the text into your bibliography or works cited list.

Because each style has its own formatting nuances that evolve over time and not all information is available for every reference entry or article, Encyclopedia.com cannot guarantee each citation it generates. Therefore, it’s best to use Encyclopedia.com citations as a starting point before checking the style against your school or publication’s requirements and the most-recent information available at these sites:

Modern Language Association

http://www.mla.org/style

The Chicago Manual of Style

http://www.chicagomanualofstyle.org/tools_citationguide.html

American Psychological Association

http://apastyle.apa.org/

Notes:
  • Most online reference entries and articles do not have page numbers. Therefore, that information is unavailable for most Encyclopedia.com content. However, the date of retrieval is often important. Refer to each style’s convention regarding the best way to format page numbers and retrieval dates.
  • In addition to the MLA, Chicago, and APA styles, your school, university, publication, or institution may have its own requirements for citations. Therefore, be sure to refer to those guidelines when editing your bibliography or works cited list.

Caffeine

CAFFEINE

OFFICIAL NAMES: Caffeine

STREET NAMES: None

DRUG CLASSIFICATIONS: Not scheduled, stimulant


OVERVIEW

Doubtlessly the most widely used drug today, caffeine is consumed daily by 90% of the world's people. Evidence of its use exists as far back as the Stone Age, and today, children, teens, and adults everywhere ingest it in coffee, tea, and soft drinks.

Legend has it that the stimulant effect of the coffee bean was first noted by an Ethiopian shepherd guarding his flock, a thousand years ago. Sufi monks steeped the berries in hot water and found that the brew helped them stay awake for long nights of prayer. Meanwhile, written records show that, during the Tang dynasty, which lasted from the seventh to the tenth century, the Chinese were already steeping and consuming tea as a drink believed to lengthen life.

By the Middle Ages, coffee was a popular drink of Muslims. In fact, the word coffee is derived from the Arabic, qahweh (pronounced kahveh). It was the Turks, however, who controlled much of the world's trade in coffee by the Middle Ages. The Turkish Empire, attempting to expand into Europe, laid siege to Vienna in1683. The war failed, but the retreating Turks left behind 500 sacks of coffee beans, which an entrepreneur used to open the first coffeehouse in Vienna. Coffee use spread throughout Europe.

In 1675, King Charles II issued an order to close the coffeehouses that were already widespread throughout England, citing idleness as the chief complaint. Two days before the proclamation was to take effect, however, Charles backed down, fearing massive protests by coffee drinkers. Ironically, in the ensuing decades, the British came to prefer tea, probably due to the acquisition of its colony in India and the establishment of the tea trade there.

The social use of coffee then spread to America. By the eighteenth century, plantations devoted to the coffee plant were actively producing the bean in Indonesia and the West Indies.

Later, during the Vietnam War, coffee also played a part in the protest movement growing at home. Coffee bars flourished near military bases across the United States, where discussions flowed, along with the coffee, over strategies to aid war protestors.

Both health claims and controversies have followed caffeine through the centuries. By the 1960s, health concerns over coffee use were raised in the medical literature as well as the popular press. Research linked coffee consumption to medical conditions such as pancreatic cancer, breast lumps, and elevated levels of cholesterol.

In 1979, a Swiss company developed a distillation method to remove the caffeine from coffee, creating decaffeinated coffee. The Swiss water process proved popular among young urban professionals as it was considered to make a more "natural" product in comparison to the earlier method of making decaffeinated coffee, which used chemicals such as methylene chloride. The Swiss method also retained more of the flavorful oils residing in the coffee bean. Caffeine-free versions of colas soon followed.

Most follow-ups to earlier studies warning of the adverse effects of caffeine have failed to duplicate the initial findings, especially for the moderate use of caffeine. However, at the start of the new millennium, youth culture thrived on the excessive use of caffeine. New drinks were purposely formulated to contain large amounts of the mild stimulant, increasing the risk of possible adverse effects.

Critics of popular beverages such as Red Bull and Adrenaline Rush suggest that the high caffeine and sugar content pose a potential risk of dehydration for athletes, and that they could also pose a significant danger for adverse effects on the heart. In addition, these high caffeine drinks are used as mixer beverages for alcohol, a potentially dangerous combination.

Some body builders tout the combination of caffeine with the herbal stimulant ephedra as harmless, and suggest the combination helps turn fat into muscle. A study published in 2001 does support the claim that caffeine and ephedrine can boost results in laboratory attempts to mimic the tasks of competing athletes. However, ephedra, the herbal drug containing the chemical ephedrine, has been linked to several deaths.

In 1980, the Food and Drug Administration (FDA) proposed to remove caffeine from its Generally Recognized As Safe list. But the FDA concluded in 1992 that, after reviewing the scientific literature, no harm is posed by a person's intake of up to 100 mg per day. As of 2001, the FDA recognized caffeine as a substance that is a food additive with a provisional listing status.

CHEMICAL/ORGANIC COMPOSITION

Caffeine, the active substance responsible for the stimulant effect of the coffee plant's berry, is a methylxanthine, one of the family of stimulants present in more than 60 species of plants. The pure chemical forms white, bitter-tasting crystals, which were first isolated from coffee in 1820. Other family members are theophylline, found in tea leaves, and theobromine, found in the cacao pods that are ground to make chocolate. The most potent component in the coffee family by unit weight is theophylline, while theobromine, the weakest component by unit weight, stays in the body longer than does caffeine.

Caffeine is also a trimethylxanthine, which is made up of three methyl groups. Efforts by the liver to deactivate caffeine at first appear counterproductive. Liver enzymes usually detoxify potentially harmful chemicals obtained through food, or those naturally present in the body. But what is left after the liver initially removes a methyl from caffeine are theophylline and paraxanthine, both of which are still active. Only when the final methyl is stripped away is the chemical inert. This production of active metabolites is why the stimulant lasts a relatively long time. It is also why people with liver disease, or those who consume other drugs that engage the liver enzymes, cannot efficiently clear caffeine from their body. Impaired caffeine metabolism is also evident in women taking estrogen for birth control or who are at the high estrogen phase of their monthly cycle. Newborn babies whose livers are not yet fully developed also break down caffeine more slowly until the enzymes are fully activated.

The methylxanthine molecule is built on a foundation common to many biologic compounds, the xanthine double ring of carbons. The three methylxanthines, caffeine, theophylline, and theobromine, all block the action of the body's adenosine molecule, sending a signal that helps slow the chemical buildup inside cells. Because the methylxanthines closely resemble adenosine at the molecular level, they can occupy the molecular sites on cells that normally recognize, and react to, adenosine. Caffeine prevents the normal slowing action of adenosine at the cellular level, in both nerves and muscle.

Scientists working with cell and tissue preparations recognized that caffeine and the other methylxanthines can block an enzyme called phosphodiesterase. It seems now, however, that this action is carried out at caffeine doses that are much higher than what people normally

consume. A similar caveat goes for the supposed action of caffeine on calcium stores in muscle. It is an effect only evident at high doses.

Caffeine is present in coffee, tea, and chocolate. These plant-derived beverages and foods also contain the other methylxanthines, which some scientists say serve as defense chemicals for leaves and berries produced in climates where there is no winter to kill off chewing bugs. Tea contains mostly caffeine, with small amounts of theophylline and theobromine, but tea is a weaker plant extract than the stronger brew, coffee. Theobromine is the primary methylxanthine found in cocoa, which also contains a small amount of caffeine per cup. Caffeine content ranges from as little as 5 mg in a cup of hot cocoa to 300 mg in 6 oz (177 ml) of espresso. Colas have about 50 mg per 12 fl oz (355 ml).

The robusta strain of coffee plant cultivated in Indonesia and Africa contains about 2.2% caffeine, while the arabica variety, grown in Central and South America, contains half that concentration. The caffeine in tea was purified in 1827, and was initially given its own name of "theine," as chemists of the day thought it different from the caffeine in coffee.

The kola nut, source of some of the flavoring of cola drinks, also has a bit of caffeine. About 5% of the 35 mg in a standard 9.5 oz (280 ml) serving of cola is naturally present from the kola nuts. The caffeine in sodas is added by the manufacturer.

Caffeine is available by prescription as a solution of caffeine citrate. Caffeine is also an active ingredient in many headache medicines, both by prescription and sold over the counter, as well as in nonprescription aids and herbal preparations for alertness and dieting. Body builders may readily buy and use a "stack," a pill comprising of ephedra, caffeine, and aspirin. Often caffeine is added intentionally to the mixes in today's energy drinks. Many abused illegal drugs, as well as some drugs sold legally, contain caffeine, either for added effect, or as a "filler," used in powder form to cut the potency of street drugs.

INGESTION METHODS

The vast majority of caffeine is ingested in a beverage such as coffee, tea, or soda. Beyond beverages, caffeine is also consumed in snacks such as chocolate candy bars, or as a component in drug medications.

THERAPEUTIC USES

Caffeine is approved as a prescription drug for treating premature infants who are born before their lungs and brain are mature enough for automatic breathing. These babies may have a condition called apnea, in which they cease breathing, which could cause damage to the brain and other organs. Caffeine has been demonstrated to aid in keeping premature babies breathing regularly. But a study published in 2001 found that very-low-birth-weight preemies also failed to gain weight when treated for their apnea with caffeine. Apparently the caffeine raised the babies' metabolic rate, causing them to burn more calories.

Many headache medications also contain caffeine, which can increase the effectiveness of the other drugs that alleviate both tension and migraine headaches. People who get migraines can have their headaches controlled by pills that combine caffeine with aspirin or acetaminophen. A study in 2000 showed that the effect of caffeine also increases the effectiveness of ibuprofen.

A study in 1999 confirmed that rebound headaches will occur if regular caffeine users suddenly cease taking the stimulant. To cut down on heavy caffeine use, it was recommended that all forms of caffeine (including caffeine-containing medications) be temporarily eliminated.

In 1999, it was reported that caffeine combined with alcohol could prevent damage from strokes. However, the doses that provide the benefit are quite specific, and the treatment has to be given at a time quite close to the stroke. Another study casts doubt on these findings, and indeed suggests that caffeine cuts blood flow in the brain, an action that would be harmful in people suffering strokes. Then, a report published in 2001 concluded that caffeine could have adverse consequences for patients trying to recover from stroke. By slowing blood flow through the brain, caffeine could starve already struggling nerve cells.

A functional magnetic resonance imaging (fMRI) study of the brain can actually determine between the regular and the occasional coffee drinker. Caffeine consistently slows blood flow by 25% to the gray matter of the brain, which contains the cells, and by 20% to the white matter, which contains the connecting nerve fibers. Heavy users of caffeine show more blood flow in the gray matter in the front of the brain when they had abstained for 30 hours, compared to those who infrequently ingest caffeine. With fMRI, the doctor can look inside the brain and observe the phenomenon of caffeine withdrawal in action.

The therapeutic treatment of obesity with caffeine is another controversial area of interest. Many over-the-counter diet aids contain caffeine, but it has not yet been determined whether there is a medically safe way to use caffeine as a fat fighter. A 2000 study showed that a combination of herbal ephedra and caffeine lowered participants' body weight by both decreasing fat and decreasing the body mass index (BMI). Losses were 15 and 7 pounds for those taking the herbal supplement and a placebo, respectively.

Green tea with caffeine also seeks to weigh in as an herbal fat fighter. The thermogenic effect of tea is carried out at various control points in the adrenergic pathway. Caffeine, through the action of phosphodiesterase enzymes, indirectly boosts the adrenergic signals. However, there is no direct evidence that green tea successfully allows people to lose weight and keep it off.

USAGE TRENDS

Caffeine is widely used due to its relative safety as compared to other stimulants. In fact, in 2001 the U.S. military endorsed the usefulness of caffeine, recommending it as a safe and effective stimulant for its soldiers.

Scope and severity

Ninety-five percent of all caffeine is consumed in the form of tea and coffee. Following water, tea is the most popular beverage in the world. About 1.5 billion cups of coffee are consumed every day throughout the world.

Since water that is not boiled is unsafe to drink in many areas of the world, travelers are advised to drink coffee and tea instead. However, the diuretic effect of caffeine can cause dehydration.

Age, ethnic, and gender trends

The average daily consumption of caffeine for adults in the United States is about 210 mg. Coffee accounts for 60% of the total caffeine consumed in the United States, while soft drinks and tea each represent 16% of the total. In the United Kingdom, by comparison, caffeine intake is twice the American rate, and tea accounts for 72% of the British total. In Scandinavian countries, coffee is the preferred beverage. For instance, in Sweden, coffee makes up 85% of the total per capita of caffeine consumption. Finland is renowned for the practice of brewing particularly potent coffee, boiled and decanted directly from ground beans.

MENTAL EFFECTS

Within minutes of consumption, a caffeinated beverage will cause the drinker to feel more alert. Simple intellectual tasks are performed more readily, as are physical jobs that require endurance. However, while reaction time is shortened by caffeine, fine motor control suffers, perhaps due to the slight tremor that becomes more pronounced with higher doses of caffeine. The larger doses of caffeine, especially for people who do not use it regularly, cause headache and nervousness.

Caffeine decreases the duration of slow waves in the electroencephalogram (EEG) for about five hours after it is ingested. Taken near bedtime, caffeine will delay the time it takes for the consumer to fall asleep, and will reduce the depth and quality of sleep. Sleepers will also move more and waken more easily. These effects are evident with the amount of caffeine present in a cup or two of coffee, approximately 75–150 mg.

PHYSIOLOGICAL EFFECTS

Caffeine, by blocking the action of the body's adenosine, affects a wide variety of organs, as well as the brain, the gut, and basic metabolism. Theophylline works more actively on respiration and the heart. Caffeine is more active in the gut and in the central nervous system. Theobromine has very weak, if any, effect on the brain, but it retains the methylxanthine effect on the kidneys, increasing urination.

Caffeine dissolves easily in fats, so it encounters no barrier as it spreads in the body when taken by mouth. It rapidly crosses the mucosa of the stomach and soaks through the blood-brain barrier. In the bloodstream, the peak level of caffeine is achieved within half an hour. It takes four hours for the body to clear half a dose of the drug. This rate of metabolism of caffeine is slower in newborns and in women late in pregnancy. Smokers, though, rid caffeine more rapidly. Children also rid their bodies of caffeine more readily than adults.

Metabolic processes speed up appreciably under the influence of caffeine. Fatty acids are released into the blood, and a general increase in metabolism is evident as there is increased muscle activity, raised temperature, or both. More calcium is made available through caffeine's action in the muscles for contraction, but this effect is evident only at caffeine doses higher than people commonly use. Gut motility and secretion increase with a release of stomach acid and digestive enzymes. Urination is also stimulated; caffeine directly affects the kidneys, cutting into their ability to reabsorb electrolytes and water. For every cup of coffee or two to three cans of caffeinated soft drink consumed, about 5 mg of calcium is lost in the urine.

Breathing rate increases in response to caffeine. The effect on respiration occurs at the level of the brain stem's respiration control center. Theophylline has the most potent action of all the methylxanthines, affecting the smooth muscle of the bronchial tree in the lungs. This is why theophylline is a treatment for asthma. Doctors may recommend weak tea for their asthmatic patients with colds; this bronchodilating action of the theophylline in the tea will aid in clearing mucus.

Caffeine temporarily increases blood pressure, but the body readily compensates and adjusts back to its normal blood pressure. However, people with hypertension may have a more sensitive response to the drug, as caffeine may raise the blood pressure to a higher level in those with chronic high blood pressure.

For migraine patients, the effect of caffeine on the blood vessels around the brain is beneficial; it constricts both the inner and outer vessels, relieving pain. Also, because caffeine increases the acidity in the stomach, it speeds the absorption of pain medications.

Sports competitors recognize that caffeine can boost performance. Large amounts of caffeine release free fatty acids into the bloodstream, reserving the stores of glycogen in muscle for later use. Two to four cups of coffee contain the amount of caffeine that can enhance exercise performance in the average man weighing about 165 lb (75 kg), and it is two to three cups for a 130-lb (59 kg) woman. A down side to caffeine use during a sporting event is the need to urinate, caused by caffeine's diuretic effect on the kidneys.

Harmful side effects

Some people find that caffeine irritates their gastrointestinal tract. It is still unclear if the effect is from caffeine itself, or from another as-yet-undetermined substance that could be in coffee. Regardless, people with stomach ulcers or irritation may not find relief by switching from caffeinated to decaffeinated coffee.

Caffeine content of common dietary and medicinal sources
source: Center for Science in the Public Interest.
<http://cspinet.org/new/cafchart.htm>
Source Standard amount
(in milligrams)
Bottled beverages (12 oz)
Red bull115.5
Jolt72
Mountain Dew55
Diet Coke45
Dr. Pepper41
Coca-Cola Classic34
Coffee (8 oz)
Brewed80–135
Instant65–100
Decaf brew3–4
Tea (8 oz)
Ice tea47
Brewed40–60
Instant30
Green tea15
Chocolate
Hot cocoa (8 oz)14
Chocolate milk (6 oz)4
Chocolate bar (1 oz)3–6
Medications (per tablet)
Vivarin200
No-doz100
Midol, Maximum Strength65
Anacin32
Dristan30

Effects of caffeine on the heart can be considerable. Rapid or irregular heartbeats can result from ingesting large amounts of caffeine. People at risk for heart attacks might be ill advised to drink coffee or indulge in other sources of caffeine. Caffeine intake exceeding the amount found in five or more cups of drip coffee a day results in a statistically increased risk of cardiac arrest.

Frankly toxic effects, such as persistent insomnia and anxiety, only become evident when people drink more than eight or nine cups of coffee or tea a day. Convulsions and delirium can follow enormous doses, and a near-fatal dose can induce a state similar to that of a diabetic lacking insulin. Blood sugar surges, and ketones appear in the urine. The lowest recorded fatal dose of caffeine was 3200 mg, which was given by accident directly into the bloodstream. It takes the equivalent of 40 cups of coffee consumed by mouth in a short interval for caffeine to kill a person.

Long-term health effects

When studies in the 1980s raised concern about possible adverse effects, including miscarriage, birth defects, and infertility, doctors advised pregnant women to cut out caffeine entirely. Most of these studies have not been confirmed. Certainly, the amounts of caffeine used to cause birth defects in rodents exceed the usual amounts consumed by people. By the year 2000, doctors simply told women who were pregnant or planning pregnancy, to keep caffeine consumption within the bounds of a cup or two of coffee a day.

Most studies find that moderate use of caffeine does not impair fertility, risk miscarriage, or increase the chance of having a baby with birth defects. The March of Dimes has concluded that moderate caffeine is of low risk to pregnant and nursing women.

A study in the early 1990s compared more than 2,800 women who had recently given birth to 1,800 women diagnosed as infertile. Caffeine habits had little or no impact on the reported time it took to conceive in those who had given birth, and was not a risk factor in the infertile. A similar study in Denmark only pointed to smoking as a factor in delayed conception.

Babies born to women who consumed large amounts of caffeine during pregnancy might demonstrate delayed growth or delayed mental or physical development. However, caffeine consumption equivalent to about a cup and a half of coffee a day had no effect on a child's birth weight, length, and head circumference; nor did it have an effect on follow-up exams of the children at eight months of age and at seven years. In a study of 1,500 women, neither the motor skills nor the intelligence of these children was affected by their mother's caffeine consumption. Review of more than 20 studies since the 1980s show no evidence that caffeine causes either low birth weight babies, or early birth.

One study carried out between 1959 and 1966 found that very high levels of a caffeine metabolite is a marker for spontaneous abortion. Measured at 11 weeks gestation, the amount of the metabolite, paraxanthine, in blood serum was higher in women who had lost a pregnancy than in women in the control group. The risk of spontaneous abortion in women with the very highest level of paraxanthine was twice that than for the women with the lowest recorded levels. The levels were measured more than 30 years later, and the findings reported in 2000.

Caffeine can enter the milk of breastfeeding mothers. Babies younger than six months cannot metabolize caffeine as well as do adults. Mothers are advised, however, that up to three cups of coffee, or several cans of soda, can be consumed without passing caffeine on to their nursing infants.

The American Cancer Society states that there does not seem to be any relationship between caffeine and cancer. However, other adverse effects for women remain a concern, such as the possibility that large amounts of caffeine could contribute to osteoporosis (thinned and fragile bones), particularly in elderly women. As caffeine is a diuretic, which increases loss of fluids and electrolytes in the urine, it could rob the body of calcium. Nevertheless, a study published in 2001 concluded that the net effect of carbonated sodas on the body's calcium is negligible, and that the loss of calcium in urine due to carbonated drinks is too small to affect calcium balance.

REACTIONS WITH OTHER DRUGS OR SUBSTANCES

Caffeine cannot sober a drunk or save someone who is lethargic or unconscious from an overdose of a sedating drug. However, because caffeine lowers stomach pH, it can affect the absorption of other substances. Other drugs such as oral contraceptives, cimetidine, disulfiram, and alcohol can delay the body's ability to rid itself of caffeine.

TREATMENT AND REHABILITATION

Legally, caffeine is not regulated as a dangerously addictive substance. Yet, withdrawal from caffeine is documented as a recognized set of symptoms in the medical literature. Many people who regularly consume caffeine and then suddenly stop will experience headache, irritability, muscle aches, and lethargy, including impaired concentration.

As with any active agent that produces a withdrawal syndrome, the common-sense approach is to gradually wean oneself from caffeine in order to minimize any symptoms. Those wishing to decrease their use should taper off slowly and perhaps substitute cups of caffeinated drinks with decaffeinated varieties or other caffeine-free beverages.

The extent to which people suffer withdrawal from caffeine use remains controversial. However, a study reported that 11,000 subjects were interviewed about their daily consumption of caffeine, among a host of other questions about lifestyle. Only 11% reported withdrawal symptoms from stopping caffeine intake, and only 3% said their symptoms interfered with daily living. Notably, that figure breaks down differently for the genders: 5.5% of women, but only 0.9% of men, reported symptoms from stopping caffeine intake that affected daily activities. Nevertheless, the study concluded that caffeine withdrawal remains a well-documented phenomenon. A major symptom of abrupt cessation of caffeine use is a headache of moderate to severe intensity that generally begins within 18 hours of the last dose. It peaks at about three to six hours of onset. The feeling is of fullness in the head that continues to a diffuse, throbbing pain, and is worsened by physical activity. Sadness and mild nausea are also reported by a quarter of those who show the withdrawal headache. Those who chronically consume 500 to 600 mg of caffeine per day are more likely to experience withdrawal if they suddenly cease their habit.

PERSONAL AND SOCIAL CONSEQUENCES

A caffeine roundtable discussion by experts concluded that there is no evidence that caffeine is linked to the socially damaging behaviors that characterize drugs of abuse.

LEGAL CONSEQUENCES

There are no legal consequences since caffeine is not a scheduled substance.

Legal history

In 1909, the federal government seized a shipment of Coca-Cola syrup, citing the added caffeine as a poisonous and deleterious substance. In 1959, caffeine was listed in the Code of Federal Regulations as generally recognized as safe, when used in cola type drinks at a level set at 0.02%, based on industry standards at that time. In 1997, the FDA required labeling of the caffeine content of foods and drinks.

Federal guidelines, regulations, and penalties

The FDA allows soft drink manufacturers to add caffeine to a limit of 72 mg per 12-ounce (355 ml) serving. Coffee and tea, containing caffeine naturally rather than as an additive, are not regulated for caffeine content.

See also Ephedra; Herbal drugs

RESOURCES

Books

Braun, Stephen. Buzz. New York: Oxford University Press, 1996.

Pendergrast, Mark. Uncommon Grounds. New York: Basic Books, 1999.

Periodicals

Bell, Douglas. "Effect of Caffeine and Ephedrine Ingestion on Anaerobic Exercise and Performance." Medicine and Science in Sports and Exercise 33 (August 2001): 1399-1403.

Cordes, Helen. "Generation Wired." The Nation (April 27,1998) On-line edition. <http://past.thenation.com/1998/980427.htm>.

Sparano, Nicole. "Is the Combination of Ibuprofen Plus Caffeine Effective for the Treatment of Tension-type Headache?" Journal of Family Practice 50 (January 2001): 312-319.

Other

Center for the Evaluation of Risks to Human Reproduction Web site. <http://cerhr.niehs.nih.gov/genpub/topics/caffeine-ccae.html>.

Cohen, Elizabeth. "Energy Drinks Pack a Punch, But Is It Too Much?" CNN.com. <http://www.cnn.com/2001/HEALTH/diet.fitness/05/29/energy.drinks.02/>. May 29, 2001 (January 30,2002).

Organizations

American College of Sports Medicine, 401 Michigan Street, Indianapolis, IN, USA, 46202-3233, (317) 637-9200, (317) 634-7817, [email protected], <http://www.acsm.org>.

National Headache Foundation, 428 W. St. James Place, 2nd Floor, Chicago, IL, USA, 60614-2750, (888) 643-5552, (773) 525-7357, (888) 643-5552, [email protected], <http://www.headaches.org>.

Roberta L. Friedman, Ph.D.

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"Caffeine." Drugs and Controlled Substances: Information for Students. . Encyclopedia.com. 12 Oct. 2018 <http://www.encyclopedia.com>.

"Caffeine." Drugs and Controlled Substances: Information for Students. . Encyclopedia.com. (October 12, 2018). http://www.encyclopedia.com/science/applied-and-social-sciences-magazines/caffeine

"Caffeine." Drugs and Controlled Substances: Information for Students. . Retrieved October 12, 2018 from Encyclopedia.com: http://www.encyclopedia.com/science/applied-and-social-sciences-magazines/caffeine

Learn more about citation styles

Citation styles

Encyclopedia.com gives you the ability to cite reference entries and articles according to common styles from the Modern Language Association (MLA), The Chicago Manual of Style, and the American Psychological Association (APA).

Within the “Cite this article” tool, pick a style to see how all available information looks when formatted according to that style. Then, copy and paste the text into your bibliography or works cited list.

Because each style has its own formatting nuances that evolve over time and not all information is available for every reference entry or article, Encyclopedia.com cannot guarantee each citation it generates. Therefore, it’s best to use Encyclopedia.com citations as a starting point before checking the style against your school or publication’s requirements and the most-recent information available at these sites:

Modern Language Association

http://www.mla.org/style

The Chicago Manual of Style

http://www.chicagomanualofstyle.org/tools_citationguide.html

American Psychological Association

http://apastyle.apa.org/

Notes:
  • Most online reference entries and articles do not have page numbers. Therefore, that information is unavailable for most Encyclopedia.com content. However, the date of retrieval is often important. Refer to each style’s convention regarding the best way to format page numbers and retrieval dates.
  • In addition to the MLA, Chicago, and APA styles, your school, university, publication, or institution may have its own requirements for citations. Therefore, be sure to refer to those guidelines when editing your bibliography or works cited list.

Caffeine

Caffeine

Caffeine is a chemical found in the beans, seeds, leaves, or bark of many plants. Caffeine is considered a chemical stimulant of the nervous system. A chemical stimulant speeds things up both mentally and physically, increasing alertness, interfering with sleep, and raising heart rate and blood pressure.

Foods and beverages made from caffeine-containing substances are widely available in and accepted by most contemporary societies. In North America, the most common food sources of caffeine include coffee, tea, and chocolate. More than 80 percent of adults in North America consume caffeine regularly. Average per capita (per person) caffeine intake in the United States has been estimated at 211 milligrams per day, in Canada at 238 milligrams, in Sweden at 425 milligrams, and in the United Kingdom at 444 milligrams per day. The world's per capita caffeine consumption is about 70 milligrams per day.

Even though caffeine-containing foods and beverages are perfectly legal and very commonly used, caffeine can affect behavior in ways that are similar to the effects of drugs of abuse. People who regularly use caffeine can experience both physical dependence and tolerance .

Caffeine has known effects on the brain. As little as 32 milligrams of caffeine, less than the amount of caffeine in most 12-ounce cola soft drinks, can improve alertness, performance, and reaction time. Doses as low as 10 milligrams, less than the amount of caffeine in some chocolate bars, can alter mood. Regular use of only 100 milligrams of caffeine per day—in other words, drinking one cup of coffee every day—can cause severe withdrawal symptoms if the daily caffeine is stopped abruptly.

Sources of Caffeine

Coffee and tea are the world's primary dietary sources of caffeine. Consumption of tea was first documented in China in 350 C.E., although there is some evidence that the Chinese first consumed tea as early as the third century B.C.E. Coffee cultivation began around 600 C.E., probably in what is now Ethiopia. Other commonly used items containing caffeine include soft drinks, cocoa products, and medications.

CAFFEINE CONTENT OF COMMON FOODS AND DRINKS
Source Standard Value (in milligrams)
Coffee (6 oz./180 ml)  
   ground roasted 102
   instant 72
   decaffeinated 4
Tea (6 oz./180 ml)  
   leaf or bag 48
   instant 36
Cola Soft Drink  
   (12 oz./360 ml) 43
Chocolate Milk  
   (6 oz./180 ml) 4
Chocolate Bar  
   (1.45–1.75 oz./40–50 g) 7
     Milk Chocolate (1.5 oz) 10
     Dark Chocolate (1.5 oz) 31
Caffeine-containing over-the-counter medications  
     analgesics and cold preparations 32
     appetite suppressants and stimulants 100

Caffeine is found in more than sixty species of plants. Coffee is derived from the beans (seeds) of several species of Coffea plants, and the leaves of Camellia sinensis plants are used in caffeine-containing teas. Chocolate comes from the seeds or beans of the caffeine-containing cocoa pods of Theobroma cacao trees. In developed countries, soft drinks, particularly colas, provide another common source of dietary caffeine. Only a portion of the caffeine in soft drinks comes from the kola nut (Cola nitida); most of the caffeine is added during manufacturing. Since the 1960s, a marked decrease in coffee consumption in the United States has been accompanied by a substantial increase in the consumption of soft drinks. Matt leaves (Ilex paraguayensis), guarana seeds, and yoco bark are other sources of caffeine for a variety of cultures. The accompanying table shows the amounts of caffeine found in common dietary and medicinal sources. As can be seen in the range of values for each source in this table, the caffeine content can vary widely depending on the method of preparation or commercial brand.

Effects on Mood and Performance

It has long been believed that caffeine stimulates mood and behavior, decreases fatigue, and increases energy, alertness, and activity. Although caffeine's effects in experimental studies have sometimes been subtle (difficult to detect) and variable, dietary doses of caffeine have a variety of effects on mood and performance. Doses below 200 milligrams have been shown to improve vigilance (alert watchfulness) and reaction time and postpone sleep. In addition, the subjects of these studies report increased alertness, energy, motivation to work, desire to talk to people, self-confidence, and well-being. Higher doses can both improve or disrupt performance of complex tasks and can cause nervousness, jitteriness, restlessness, and anxiousness.

Medical Uses of Caffeine

Caffeine is an ingredient in a variety of over-the-counter medications such as analgesics or painkillers (particularly to treat headaches), stimulants, and decongestants. It is also used in treatments for menstrual pain and appetite suppressants. Although caffeine is a common ingredient in headache preparations (including some prescription drugs to treat migraine headaches), evidence for caffeine's effectiveness for relieving headaches is limited, as is the evidence for its appetite-suppressant effects. Caffeine has also been used to treat:

  • chronic obstructive pulmonary disease
  • asthma
  • breathing problems in newborns
  • overdoses with opioid drugs

The Medical Risks of Caffeine

Although more research is needed, some researchers are concerned that there may be an association between caffeine intake and such diseases as benign fibrocystic breast disease and cancer of the pancreas, kidney, lower urinary tract, and breast. In a recent survey of physician specialists, more than 65 percent recommended reductions in caffeine in patients with cardiac arrhythmia (irregular heartbeat), palpitations, tachycardia (rapid heartbeat), esophagitis/hiatal hernia, fibrocystic disease, or ulcers, as well as in patients who are pregnant.

Caffeine Abuse

Case reports have described individuals who consume large amounts of caffeine—more than one gram (1,000 milligrams) per day. This excessive intake is called caffeinism, and occurs most often in psychiatric patients, drug and alcohol abusers, and anorectic patients. Caffeinism can produce a range of symptoms—muscle twitching, anxiety, restlessness, nervousness, insomnia (inability to fall asleep or stay asleep), rambling speech, tachycardia, cardiac arrhythmia, and sensory disturbances including ringing in the ears and flashes of light. Some research has also linked caffeinism with psychoses and anxiety disorders . Extremely high doses of caffeine—between 5,000 and 10,000 milligrams—can produce convulsions and death and have been shown to produce birth defects in mammals.

The American Psychiatric Association recognizes a condition known as caffeine intoxication, in which high doses of caffeine produce adverse effects. Substantial amounts of caffeine are also used by a small percentage of competitive athletes, who believe that caffeine will enhance their athletic performance, despite rules against such use.

Tolerance and Physical Dependence

Regular caffeine use can decrease a person's responsiveness to its effects. This result is known as tolerance. At first, daily doses of 250 milligrams of caffeine can cause blood pressure to go up and increase the production of urine and saliva. After several days of caffeine use, however, tolerance develops. With tolerance to caffeine, blood pressure and urine and saliva production return toward normal. Caffeine tolerance has not been well researched, although there is some suggestion that sleep-disturbing effects and jitteriness noticed when caffeine is first used both lessen after regularly using caffeine.

Uncomfortable symptoms occur when caffeine use is suddenly stopped. Caffeine withdrawal is typically characterized by reports of headache, fatigue, drowsiness, and decreased alertness. Severe withdrawal can interfere with normal functioning and include flu-like symptoms, fatigue, severe headache, nausea, and vomiting. In general, caffeine withdrawal begins twelve to twenty-four hours after stopping caffeine use and lasts from two to seven days. Caffeine withdrawal can occur following termination of caffeine doses as low as 100 milligrams per day, an amount equal to one strong cup of coffee, two strong cups of tea, or three soft drinks. These data indicate that the large majority of the adult population of the United States is at risk for significant disruption of mood and behavior when there are interruptions of daily caffeine consumption.

see also Addiction: Concepts and Definitions; Chocolate; Coffee; Cola Drinks; Tea.

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"Caffeine." Drugs, Alcohol, and Tobacco: Learning About Addictive Behavior. . Encyclopedia.com. 12 Oct. 2018 <http://www.encyclopedia.com>.

"Caffeine." Drugs, Alcohol, and Tobacco: Learning About Addictive Behavior. . Encyclopedia.com. (October 12, 2018). http://www.encyclopedia.com/education/applied-and-social-sciences-magazines/caffeine

"Caffeine." Drugs, Alcohol, and Tobacco: Learning About Addictive Behavior. . Retrieved October 12, 2018 from Encyclopedia.com: http://www.encyclopedia.com/education/applied-and-social-sciences-magazines/caffeine

Learn more about citation styles

Citation styles

Encyclopedia.com gives you the ability to cite reference entries and articles according to common styles from the Modern Language Association (MLA), The Chicago Manual of Style, and the American Psychological Association (APA).

Within the “Cite this article” tool, pick a style to see how all available information looks when formatted according to that style. Then, copy and paste the text into your bibliography or works cited list.

Because each style has its own formatting nuances that evolve over time and not all information is available for every reference entry or article, Encyclopedia.com cannot guarantee each citation it generates. Therefore, it’s best to use Encyclopedia.com citations as a starting point before checking the style against your school or publication’s requirements and the most-recent information available at these sites:

Modern Language Association

http://www.mla.org/style

The Chicago Manual of Style

http://www.chicagomanualofstyle.org/tools_citationguide.html

American Psychological Association

http://apastyle.apa.org/

Notes:
  • Most online reference entries and articles do not have page numbers. Therefore, that information is unavailable for most Encyclopedia.com content. However, the date of retrieval is often important. Refer to each style’s convention regarding the best way to format page numbers and retrieval dates.
  • In addition to the MLA, Chicago, and APA styles, your school, university, publication, or institution may have its own requirements for citations. Therefore, be sure to refer to those guidelines when editing your bibliography or works cited list.

Caffeine

Caffeine

Caffeine is an alkaloid found in coffee, tea, chocolate, and other natural foods. It is also a component of cola soft drinks. Caffeine has been a part of the human diet for many centuries and is one of the most widely used central nervous system stimulants worldwide. In recent years, research has raised questions about possible deleterious health effects of caffeine, but no definitive conclusions have been reached about the harmfulness of moderate amounts.


Chemistry of caffeine

Caffeine's chemical name is 3,7-dihydro-1,3,7-trimethyl-1H-purine-2,6-dione. It is also known as theine, methyl theobromine, and 1,3,7-trimethylxanthine. Its molecular formula is C8H10N4O2• H2O, and it consists of bicyclic molecules derived from the purine ring system.

In its pure form, caffeine is a fleecy white solid or long silky crystals. It is odorless, but has a distinctive bitter taste . When heated, caffeine loses water at 176°F (80°C), sublimes at 352.4°F (178°C), and/or melts at 458.2°F (236.8°C). It is only slightly soluble in water and alcohol , but dissolves readily in chloroform . Water solutions of caffeine are essentially neutral (pH = 6.9).

Caffeine is a member of the alkaloid family, a group of compounds obtained from plants whose molecules consist of nitrogen-containing rings. In general, alkaloids tend to have identifiable physiological effects on the human body, although these effects vary greatly from compound to compound.


History

The pleasures of coffee, tea, and chocolate drinking have been known to humans for centuries, but the isolation of caffeine from these beverages was accomplished only in the early 1800s. During the 1820s, researchers identified the active agents in tea and chocolate and gave them a variety of names such as guaranin. In 1840, T. Martins and D. Berthemot independently showed that these compounds are all identical with caffeine. Caffeine itself was originally called cofeine or caffein and only in the late 1820s was given the name by which we know it today.

Much of the work leading to the full characterization of caffeine's molecular structure was completed by the German chemist Emil Fischer (1852-1919). Fischer first synthesized the compound from raw materials in 1895, and two years later derived its precise structural formula.


Sources

Of all the commercial sources of caffeine, guarana paste has the highest concentration of the pure compound, about 4%. Guarana paste is made from the seed of the Paullinia tree , found primarily in Brazil. More common sources of caffeine contain lower concentrations of the compound: 1.1-2.2% in coffee beans; 3.5% in tea leaves; and 1.5% in kola nuts. Other less common sources of caffeine include maté leaves, obtained from the Ilex plant (less than 0.7% caffeine), and yoco bark , obtained from the Paullinia yoco tree (2.7% caffeine).

Because of the way in which these foods are prepared, the above data do not give an accurate picture of the amount of caffeine that people consume. The average cup coffee, for example, contains approximately 100-150 mg of caffeine; the average cup of tea, 50 mg of caffeine; and the average cup of cocoa, about 5 mg of caffeine. Cola drinks tend to contain 35-55 mg of caffeine, and the average chocolate bar contains about 20 mg of the compound. In 1997, more products were introduced that contained caffeine including bottled water and chewing gum.


Pharmacological effects

The most important physiological effect of caffeine is that it stimulates nerve cells, particularly those in the brain . It appears that caffeine molecules bind to neurotransmitter receptor sites in nerve cells, causing the continual stimulation of those cells. This property explains the most common clinical symptoms of caffeine ingestion: wakefulness, excitability, increased mental awareness, and restlessness.

Caffeine affects nerve tissue in the brain much more quickly than it does nerve tissue anywhere else in the body. As a result, it will bring about muscular changes such as convulsions only with very high doses of the drug—10 g or more, the equivalent of drinking 70-100 cups of coffee in a short time. Death from caffeine overdose is, therefore, extremely unlikely.


Teratogenic and mutagenic effects

Concerns about the possible health effects of consuming caffeine have been expressed for well over a hundred years. Recent concern about its physiological effects tend to focus on mutagenic and teratogenic effects. Mutagenic effects are those that change the reproductive genes, producing mutations in subsequent generations. Scientific reports have also appeared connecting the consumption of large doses of caffeine with particular types of cancer . However, the significance of such findings to the average coffee or tea drinker is unclear.

The situation with teratogenic effects—those that affect the fetus while it is still in the womb—is somewhat clearer. Caffeine passes readily across the placental lining, exposing the fetus to concentrations of the stimulant that are comparable to those in the mother's blood . Since the developing nervous system of the fetus is more likely to be affected by the drug than is the mother's, a reduction in caffeine intake is often recommended for pregnant women.

Resources

books

Dews, Peter B., ed. Caffeine: Perspectives from Research. Berlin: Springer-Verlag, 1984.

Gilbert, Richard J. Caffeine: The Most Popular Stimulant. New York: Chelsea House, 1986.

Selinger, Ben. Chemistry in the Marketplace. 4th ed. Sydney: Harcourt Brace Jovanovich, 1989.


David E. Newton

KEY TERMS

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Mutagenic

—Any substance or form of energy that can bring about changes in DNA molecules, thereby leading to changes in an organism's genetic make-up.

Pharmacological

—Having to do with the properties, uses, and effects of drugs.

Teratogenic

—Any substance that can bring about changes in a fetus prior to birth.

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"Caffeine." The Gale Encyclopedia of Science. . Encyclopedia.com. 12 Oct. 2018 <http://www.encyclopedia.com>.

"Caffeine." The Gale Encyclopedia of Science. . Encyclopedia.com. (October 12, 2018). http://www.encyclopedia.com/science/encyclopedias-almanacs-transcripts-and-maps/caffeine-1

"Caffeine." The Gale Encyclopedia of Science. . Retrieved October 12, 2018 from Encyclopedia.com: http://www.encyclopedia.com/science/encyclopedias-almanacs-transcripts-and-maps/caffeine-1

Learn more about citation styles

Citation styles

Encyclopedia.com gives you the ability to cite reference entries and articles according to common styles from the Modern Language Association (MLA), The Chicago Manual of Style, and the American Psychological Association (APA).

Within the “Cite this article” tool, pick a style to see how all available information looks when formatted according to that style. Then, copy and paste the text into your bibliography or works cited list.

Because each style has its own formatting nuances that evolve over time and not all information is available for every reference entry or article, Encyclopedia.com cannot guarantee each citation it generates. Therefore, it’s best to use Encyclopedia.com citations as a starting point before checking the style against your school or publication’s requirements and the most-recent information available at these sites:

Modern Language Association

http://www.mla.org/style

The Chicago Manual of Style

http://www.chicagomanualofstyle.org/tools_citationguide.html

American Psychological Association

http://apastyle.apa.org/

Notes:
  • Most online reference entries and articles do not have page numbers. Therefore, that information is unavailable for most Encyclopedia.com content. However, the date of retrieval is often important. Refer to each style’s convention regarding the best way to format page numbers and retrieval dates.
  • In addition to the MLA, Chicago, and APA styles, your school, university, publication, or institution may have its own requirements for citations. Therefore, be sure to refer to those guidelines when editing your bibliography or works cited list.

Caffeine

Caffeine

OVERVIEW

Caffeine (kaf-EEN) is an organic base that occurs naturally in a number of plant products, including coffee beans, tea leaves, and kola nuts. It occurs as a fleecy white crystalline material, often in the form of long, silky needles. It usually exists as the monohydrate, C8H10N4O2·H2O, although it gives up its water of hydration readily when exposed to air.

Scientists believe that humans have been drinking beverages that contain caffeine for thousands of years. The first recorded reference to a caffeine drink can be found in a Chinese reference to the consumption of tea by the emperor Shen Nung in about 2700 bce. Coffee is apparently a much more recent drink, with the earliest cultivation of the coffee tree dated at about 575 ce in Africa.

KEY FACTS

OTHER NAMES:

Methyltheobromine; theine

FORMULA:

C8H10N4O2

ELEMENTS:

Carbon, hydrogen, nitrogen, oxygen

COMPOUND TYPE:

Organic base (alkaloid)

STATE:

Solid

MOLECULAR WEIGHT:

194.19 g/mol

MELTING POINT:

238°C (460°F)

BOILING POINT:

Not applicable; begins to sublime at about 90°C (190°F)

SOLUBILITY:

Slightly soluble in water and alcohol; soluble in chloroform

Caffeine was first studied scientifically by two French chemists, Joseph Bienaimé Caventou (1795–1877) and Pierre Joseph Pelletier (1788–1842), who were very interested in the chemical properties of the alkaloids. Between 1817 and 1821, Caventou and Pelletier successfully extracted caffeine, quinine, strychnine, brucine, chinchonine, and chlorophyll (not an alkaloid) from a variety of plants. The first synthesis of caffeine was accomplished in 1895 by the German chemist Emil Hermann Fischer (1852–1919), who was awarded the 1902 Nobel Prize in chemistry for his work on the alkaloids.

Caffeine belongs to a class of alkaloids called the methylxanthines. Chocolate, from the cocoa tree Theobroma cacao contains another member of the class, theobromine. Both caffeine and theobromine are stimulants, that is, compounds that act on the nervous system to produce alertness, excitement, and increased physical and mental activity.

HOW IT IS MADE

Caffeine can be extracted from coffee, tea, and kola plants by one of three methods. These methods are used primarily to produce the decaffeinated counterparts of the products: decaffeinated coffee, decaffeinated tea, or decaffeinated soft drinks. A commercial variation of these procedures is to treat the waste products of tea or coffee processing, such as the dust and sweepings collected from factories, for the extraction of caffeine.

In the first of the three extraction methods, the natural product (coffee beans, tea leaves, or kola beans) are treated with an organic solvent that dissolves the caffeine from the plant material. The solvent is then evaporated leaving behind the pure caffeine. A second method follows essentially the same procedure, except that hot water is used as the solvent for the caffeine. A more recent procedure involves the use of supercritical carbon dioxide for the extraction process. Supercritical carbon dioxide is a form of the familiar gas that exists at high temperature and high pressure. It behaves as both a liquid and a gas. Not only is the supercritical carbon dioxide procedure an efficient method of extracting caffeine, but it has virtually none of the harmful environmental and health problems associated with each of the other two methods of extraction.

Interesting Facts

  • Americans drank 6.3 billion gallons of coffee, 2.4 billion gallons of tea, and 15.3 billion gallons of caffeinated soft drinks in 2003.

Caffeine is also made synthetically by heating a combination of the silver salt of theobromine (C7H8N4O2Ag) with methyl iodide (CH2I), resulting in the addition of one carbon and two hydrogens to the theobromine molecule and converting it to caffeine.

COMMON USES AND POTENTIAL HAZARDS

Caffeine is used in foods and drinks and for medical purposes. Its primary action is to stimulate the central nervous system. People drink coffee, tea, or cola drinks to stay awake and alert because caffeine creates a feeling of added energy. It does this by increasing heart rate, improving blood flow to the muscles, opening airways to aid breathing, and releasing stored energy from the liver to provided added fuel for the body. In large quantities, caffeine can also cause nervousness, insomnia, and heart problems. The effects of caffeine can linger in the body for more than six hours. In medical applications, caffeine is sometimes used as a heart stimulant for patients in shock, to treat apnea (loss of breathing) in newborn babies, to counteract depressed breathing levels as a result of drug overdoses, and as a diuretic.

Caffeine stimulates the brain in two ways. First, because it has a chemical structure similar to that of adenosine, it attaches to adenosine receptors in the brain. Adenosine is a substance that normally attaches to those receptors, slowing brain activity and causing drowsiness. By blocking those receptors, caffeine increases electrical activity in the brain, creating a feeling of alertness. Caffeine also works in the brain like drugs such as heroin and cocaine, although in a much milder way. Like those drugs, caffeine increases dopamine levels. Dopamine is a chemical present in the brain that increases the body's feeling of pleasure.

Words to Know

ALKALOIDS
Organic bases that contain the element nitrogen.
DIURETIC
A substance that increases the flow of urine.
WATER OF HYDRATION
Water that has combined with a compound by some physical means.

Studies have shown that caffeine can become addictive. People who use the compound eventually need to take more and more of it to get the same effect. When some people try to stop using caffeine, they may suffer from headache, fatigue, and depression, though these symptoms can be controlled by gradually reducing the amount of caffeine consumed. Either way, withdrawal symptoms end after about a week.

FOR FURTHER INFORMATION

"Caffeine." Neuroscience for Kids. http://faculty.washington.edu/chudler/caff.html (accessed on September 23, 2004).

"Caffeine Chemistry." Erowid Vault. http://www.erowid.org/chemicals/caffeine/caffeine_chemistry.shtml (accessed on September 23, 2005).

Cherniske, Stephen. Caffeine Blues: Wake Up to the Hidden Dangers of America's #1 Drug. New York: Warner Books, 1998.

Kluger, Jeffrey. "The Buzz on Caffeine." Time (December 20, 2004): 52.

Weinberg, Alan Bennet, and Bonnie K. Bealer. The World of Caffeine: The Science and Culture of the World's Most Popular Drug. New York: Routledge, 2002.

See AlsoCarbon Dioxide; Theobromine

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"Caffeine." Chemical Compounds. . Encyclopedia.com. 12 Oct. 2018 <http://www.encyclopedia.com>.

"Caffeine." Chemical Compounds. . Encyclopedia.com. (October 12, 2018). http://www.encyclopedia.com/science/academic-and-educational-journals/caffeine

"Caffeine." Chemical Compounds. . Retrieved October 12, 2018 from Encyclopedia.com: http://www.encyclopedia.com/science/academic-and-educational-journals/caffeine

Learn more about citation styles

Citation styles

Encyclopedia.com gives you the ability to cite reference entries and articles according to common styles from the Modern Language Association (MLA), The Chicago Manual of Style, and the American Psychological Association (APA).

Within the “Cite this article” tool, pick a style to see how all available information looks when formatted according to that style. Then, copy and paste the text into your bibliography or works cited list.

Because each style has its own formatting nuances that evolve over time and not all information is available for every reference entry or article, Encyclopedia.com cannot guarantee each citation it generates. Therefore, it’s best to use Encyclopedia.com citations as a starting point before checking the style against your school or publication’s requirements and the most-recent information available at these sites:

Modern Language Association

http://www.mla.org/style

The Chicago Manual of Style

http://www.chicagomanualofstyle.org/tools_citationguide.html

American Psychological Association

http://apastyle.apa.org/

Notes:
  • Most online reference entries and articles do not have page numbers. Therefore, that information is unavailable for most Encyclopedia.com content. However, the date of retrieval is often important. Refer to each style’s convention regarding the best way to format page numbers and retrieval dates.
  • In addition to the MLA, Chicago, and APA styles, your school, university, publication, or institution may have its own requirements for citations. Therefore, be sure to refer to those guidelines when editing your bibliography or works cited list.

Caffeine

Caffeine


What Kind of Drug Is It?

Caffeine is a natural stimulant. A stimulant is a substance that increases the activity of a living organism or one of its parts. Caffeine was named after the shrubby coffee plant, which is native to the eastern African nation of Ethiopia. Although coffee is an ancient drink, it was not until 1821 that German chemist Friedlieb Ferdinand Runge finally isolated caffeine from the coffee bean.

Chemically speaking, caffeine is a bitter white alkaloid. Its chemical formula is C8H10N4O2, and it is found especially in coffee and tea. Caffeine is considered both a drug and a psychoactive substance. Such substances alter the user's mental state or change behavior.

As a mild stimulant, it is often used medicinally to treat certain kinds of headache pain. Caffeine consumption speeds up the rate at which chemical reactions occur in the body. By increasing the heart and breathing rates, it helps more oxygen get to the brain. It also acts as a diuretic (pronounced die-er-EH-tik), a substance that reduces bodily fluids by increasing the production of urine.

Overview

Caffeine is said to be consumed on a regular basis by up to 90 percent of the world's people. Humankind's fascination with caffeine dates back to prehistoric times. Andrew Weil and Winifred Rosen retold the story of coffee's accidental discovery in From Chocolate to Morphine. "Legend has it that coffee was first discovered long ago by Ethiopian nomads [or wanderers] who noticed that their domestic animals became frisky" after eating the red fruit of a certain shrub. "When people tried eating the seeds," continued the authors, "they got frisky, too, and eventually they learned to make a flavorful drink from the roasted seeds." By the fifteenth century, just as the Middle Ages (c. 500–c. 1500) were coming to a close, coffee had become a popular drink in the Arab world.

Official Drug Name: Caffeine

Also Known As: None

Drug Classifications: Not scheduled; stimulant

Thousands of years earlier, the Chinese were already steeping and drinking tea as a beverage believed to lengthen life.


A Chinese myth about the discovery of tea dates back more than 4,000 years. According to the tale, a Chinese emperor brewed the first cup of tea after a mysterious leaf fell into the water his servant had boiled for him. The leaf, so the story goes, was from a wild tea tree.

The Road from Picking to Profits

Centuries of war, land-grabbing, oceanic explorations, and trading led to the arrival of coffee and tea in Europe by the 1500s. Coffee use spread throughout the continent and then to America. In the eighteenth century, coffee plantations were actively producing the bean in Indonesia and the West Indies.

Since then, caffeine has been credited with transforming the United States and countries in Europe from agricultural nations to industrial nations. This change has made "the modern world


possible," wrote T. R. Reidin National Geographic in 2005. "Boiling water to make coffee or tea helped decrease the incidence of disease among workers in crowded cities. And the caffeine in their systems kept them from falling asleep over the machinery."

Coffee farming in the South American nation of Colombiais done the old-fashioned way, noted Ruth Morris in Life in 2005. The process "still relies on strained back muscles, wooden tools, and traditional methods" such as mule power "that haven't changed much since coffee was first produced here in the early 1800s." After observing coffee farmers firsthand, Morris explained: "It's a long way from these Colombian hills to 'Skim latte, no foam, please."'

What Is It Made Of?

Caffeine, the active substance responsible for the stimulant effect of the coffee plant's berry, is a xanthine. Xanthines are compounds made of the elements carbon, hydrogen, nitrogen, and oxygen. Some xanthines occur in the blood, urine, and muscle tissue of animals; others are found in certain plants.

The caffeine xanthine is one of the family of stimulants present in more than sixty different species of plants. The pure chemical is a yellowish-white, bitter crystal. Other xanthines related to caffeine include theophylline and theobromine. The pods of cacao beans (better known in the United States as cocoa beans) are ground to make chocolate.

How Is It Taken?

The vast majority of caffeine is ingested in a beverage such as coffee, tea, or soft drinks. Beyond beverages, caffeine is also consumed in snacks such as chocolate candy bars. Pain relievers, including aspirin, acetaminophen, and ibuprofen, may contain some caffeine. The stimulant effects of the caffeine allow the pain relievers to act more quickly.

Caffeine is also found in nonprescription aids and herbal preparations for alertness and dieting. Pure caffeine in tablet form is available over-the-counter in substances such as No-Doz and Vivarin. The caffeine in these tablets has the same effect as the caffeine found in coffee or tea—it is just more concentrated. Many abused illegal drugs contain caffeine, either for added effect or as a "filler," used in powder form to cut the strength of street drugs.

Crazy for Coffee


How much do you know about coffee? Ruth Morris' article "America's Bottomless Cup" in Life magazine and the Web site www.coffeekids.org offer many interesting facts about growing, producing, and drinking coffee. For example, did you know that:

  • It takes 4,000 coffee beans to produce one pound of coffee; that is more beans than the average coffee tree yields in a year.
  • Americans consume 3 billion pounds of coffee each year.
  • Worldwide coffee consumption is estimated at 11 billion pounds per year.
  • The average coffee farm in the poverty-stricken nation of Colombia makes about $1,900 each year.
  • The female Colombian farm workers who pick out flawed coffee beans—by hand—from enormous troughs of beans make only $5 per day.
  • In the coffee-growing regions of Mexico, Guatemala, Nicaragua, and Costa Rica, most coffee farmers earn just a few pennies per pound for their harvest.

CNN medical correspondent Dr. Sanjay Gupta told interviewer Daryn Kagan that people need to be more informed about the "hidden" caffeine content in the foods they eat. "Half a cup of … coffee ice cream from Häagen-Dazs has actually more caffeine than a Coke," remarked Gupta. "Most people are surprised by that." Another example cited by Gupta involved carbonated soft drinks. Ounce for ounce, Sunkist orange soda—a beverage not often thought of as a high source of caffeine—has nearly the same caffeine content as a Coke.


Many people think that dark-colored soft drinks contain caffeine and the light-colored ones do not. However, many popular root beers contain no caffeine while the light-colored Mountain Dew contains more caffeine than a regular Coke. Some manufacturers now offer their popular products in caffeine-free versions as well. If in doubt, check the ingredients on the can or bottle. It will note if the beverage contains caffeine or not.

MSNBC.com reported in 2004 that "in North America, 80 percent to 90 percent of adults drink caffeine regularly." Each day in the United States, the average person consumes about 280 milligrams of caffeine, which equals roughly a mug or two of coffee or three to five cans of soft drinks.

How Much Caffeine Is in That?


Ever wonder how much caffeine is in a certain product? Various Web sites list the caffeine content of many of the most popular products containing caffeine. Among those Web sites are: American Beverage Association <http://www.ameribev.org/health/caffeinecontent.asp> and Center for Science in the Public Interest <http://cspinet.org/new/cafchart.htm>. Here are some examples of popular products and their caffeine content:

Soft Drinks

  • 12 oz. A&W Root Beer: 0 mg
  • 12 oz. Coca-Cola: 34 mg
  • 12 oz. Diet Coke: 45 mg
  • 12 oz. Mountain Dew: 55 mg
  • 12 oz. Sunkist Orange: 42 mg

Energy Drinks

  • 12 oz. Red Bull: 115 mg

Coffee, Tea, Hot Chocolate

  • 8 oz. coffee (brewed): 80-135 mg
  • 8 oz. decaffeinated coffee (brewed): 3-5 mg
  • 8 oz. tea (brewed): 40-60 mg
  • 8 oz. iced tea: 15-40 mg (depending on brand)
  • 8 oz. hot chocolate: 5-14 mg

Candy Bars

  • 1.5 oz. milk chocolate bar: 10 mg
  • 1.5 oz. dark chocolate bar: 31 mg

Over-the-Counter Pills

  • 1 tablet No-Doz: 100 mg
  • 1 tablet Excedrin: 65 mg
  • 1 tablet Midol: 32.4 mg

Are There Any Medical Reasons for Taking This Substance?

Many headache medications contain caffeine, which helps speed up the action of analgesics. Because caffeine cuts blood flow in the brain, it should not be used by people at risk for or recovering from a stroke. By slowing blood flow through the brain, caffeine could starve already struggling nerve cells. Rumors of caffeine's effectiveness and safety as a weight loss agent have persisted for years, but they have never been medically proven.

Breathing rates increase in response to caffeine. Theophylline has an especially strong effect on respiration, affecting the smooth muscle of the bronchial tree in the lungs. This is why theophylline is sometimes used as a treatment for asthma. Doctors may recommend weak tea for their asthmatic patients with colds, as the tea will aid in clearing mucus from the respiratory tract.


Usage Trends

Ninety-five percent of all caffeine is consumed in the form of tea and coffee. In the United States and Scandinavian countries, coffee is the main source of total caffeine consumption. In the United Kingdom, tea accounts for about three-quarters of the total caffeine intake. Following water, tea is the most popular beverage in the world.

"People generally take caffeine in forms so diluted as to make it highly unlikely that excessive doses—more than 300 or 400 milligrams at a sitting—will be ingested," noted Edward M. Brecher in The Consumers Union Report on Licit and Illicit Drugs. "People have also developed the custom of drinking coffee and tea after a meal," he added, offering "further protection for the stomach lining."

From Beans and Leaves to Power Drinks

Both health claims and controversies have followed caffeine through the centuries. Studies warning of the harmful effects of caffeine began surfacing in the 1960s. By the early 2000s, though, most follow-ups to those studies failed to duplicate the initial findings. Around the same time, youth culture began to thrive on the excessive use of caffeine. New drinks such as Red Bull, Jolt, and Adrenaline Rush purposely contained large amounts of the stimulant.

Although moderate use of caffeine has been deemed safe by medical researchers, the "power drinks" of the twenty-first century increased the risk of possible negative effects on users. While doing research in London, Reid interviewed several young users of Red Bull. "I've had eight.… I'm flying," reported one. Another compared drinking two tins of the energy drink to "drinking a pint of speed."

Critics of popular beverages such as Red Bull and Adrenaline Rush suggest that the caffeine content, along with the massive doses of sugar in each can, pose a significant health risk. These drinks do provide users with an energy boost. But some researchers think they also increase the chance of dehydration among athletes and all-night dancers. The high sugar content of the drinks impairs the body's ability to replenish fluids lost through sweat.

Energy drinks are also used as mixers for alcoholic drinks. The combination of the two can cause heart damage. In addition, "people who ingest a lot of caffeine, a stimulant, along with a lot of alcohol … won't realize how drunk they really are," warned Elizabeth Cohen on the CNN.com/HEALTH Web site. This could lead people to believe they are capable of driving when they really are not.

Effects on the Body

"The reasons for the attraction" to caffeine, wrote Jennie Kim in The Hoya, "lie in the short-term effects … often referred to as a caffeine 'lift."' Within about fifteen minutes of consumption, a caffeinated beverage will cause the drinker to feel more alert. But, according to Reid, "the instant surge is mostly placebo"—the belief that the substance will produce a desired effect in the user, even if the substance itself is not capable of producing that effect. Reid added: "[C]affeine's effects don't peak for up to an hour after it hits the bloodstream."

Caffeine Consumption


Many people throughout the world consume caffeine every day. Caffeine is found in coffee, tea, soft drinks, chocolate, and even over-the-counter drugs, among other products. Here are more facts about this popular natural stimulant.

  • Medical experts recommend that the caffeine intake for children be limited to 100 milligrams daily.
  • The average daily consumption of caffeine for adults in the United States is about 280 milligrams.
  • Approximately 600 milligrams of caffeine have the same stimulating effect as 20 milligrams of amphetamines (am-FETT-uh-meens). (Prescription-only stimulant drugs, amphetamines increase mental alertness, reduce appetite, and help keep users awake.)
  • About 1.5 billion cups of coffee are consumed every day throughout the world.
  • Most of the caffeine in soft drinks is added by the manufacturers. The kola nut, the source of some of the flavoring of cola drinks, has only a bit of caffeine, providing about 5 percent of the total amount in a standard serving.

Whether it takes fifteen minutes or sixty minutes after consumption for a "caffeine buzz" to kick in, the stimulant effects of this substance are very real. Simple intellectual tasks are performed more readily, as are physical jobs that require endurance. However, fine motor movements may become more difficult to carry out, perhaps due to the slight hand tremors


that become more pronounced with higher doses of caffeine. Larger doses of caffeine, especially in people who do not use it regularly, typically cause headache and nervousness.

The effects of caffeine last for about five hours after it is ingested. Taken near bedtime, caffeine will delay the time it takes for the user to fall asleep. It will also reduce the depth and quality of sleep. These effects are evident with the amount of caffeine present in a cup or two of coffee, approximately 80 to 250 milligrams. People who have consumed caffeine shortly before trying to sleep tend to move around in bed more and wake up more easily than sleepers who have not consumed caffeine prior to bedtime.

More Harmful Side Effects

After being taken by mouth, caffeine dissolves easily in body fats. It does not encounter any barrier as it spreads throughout the body, so it rapidly crosses the mucosa (the mucus membrane) of the stomach and soaks through the blood-brain barrier. Caffeine affects the brain, the digestive system, heart and breathing rates, and the kidneys. When consumed in very large amounts, it can cause users to experience an increase in muscle activity, a rise in body temperature, a decrease in appetite, and problems sleeping.

In addition to increased heartbeat and rate of respiration, stomach acid production rises, sometimes causing indigestion. Urination is also stimulated. Caffeine directly affects the kidneys, cutting their ability to reabsorb electrolytes and water. For every single cup of coffee or two to three cans of caffeinated soft drink consumed, about five milligrams of calcium, an important electrolyte, are lost in the urine.

Caffeine temporarily increases blood pressure. In healthy users, the body is able to compensate for this increase and adjust back to its normal blood pressure rate. However, people with hypertension or who are at high risk for heart attacks may have a more sensitive response to the drug and are advised to minimize their caffeine intake. Even in people without heart disease, the effects of caffeine on the heart can be considerable. Rapid or irregular heartbeats can result from ingesting the substance in very large amounts.

For migraine headache sufferers, the effect of caffeine on the blood vessels around the brain is beneficial. It constricts both the inner and outer vessels, relieving pain. Also, because caffeine-containing drinks such as coffee increase the acidity in the stomach, they speed the absorption of pain medications. Some people, however, find that caffeine irritates their stomachs and intestinal tracts. It is still unclear if the effect is from the caffeine itself, or from another asyet-undetermined substance that could be in coffee. Large amounts of caffeine may also contribute to osteoporosis, particularly in elderly women.

Caffeine Can Be Toxic

Toxic or poisonous effects, such as persistent insomnia and anxiety, only become evident when people drink more than eight or nine cups of coffee or tea a day. Insomnia is when someone has difficulty falling asleep or an inability to sleep. Anxiety is a feeling of being extremely overwhelmed, restless, fearful, and worried.

Convulsions and delirium can follow enormous doses. Morris noted that the amount of caffeine in forty-nine eight-ounce cups of coffee can actually be fatal to a human being if consumed by mouth in a short period of time. That works out to about 4,000 to 6,600 milligrams of caffeine in a sitting.

Dangers can occur when caffeine-containing beverages are mixed with caffeine tablets such as No-Doz or Vivarin, both of which are sold without a prescription at drugstores. These tablets have high concentrations of caffeine in them. Taking them at higher than recommended doses, especially along with coffee, tea, or other caffeinated drinks, can cause toxic results.

Women and Caffeine, 1969


In 1969, Dr. Avram Goldstein and Dr. Sophia Kaizer, both of the Stanford University School of Medicine, decided to examine why so many people drink coffee. They focused their study on the coffee-drinking habits of 239 young women.

The women were asked a series of questions. A full 60 percent of them claimed that they drank their first cup of coffee in the morning "because they needed it." Heavier users reported symptoms of withdrawal when they skipped their morning coffee. These symptoms ranged from "headache" and "irritability" to an "inability to work effectively."

The next phase of the experiment produced interesting results. Some of the women agreed to brew and drink nine unmarked vials of coffee—one each morning over the course of nine days. Three of the vials contained no caffeine, three contained 150 milligrams of caffeine, and three contained 300 milligrams of caffeine. Each day, the group was asked to record their moods every half hour for two hours after drinking whatever vial they brewed that day. None of them knew who was drinking what each morning.

The Goldstein–Kaizer study is credited with proving that caffeine is indeed a mind-affecting drug. Heavy coffee drinkers reported feeling nervous, sluggish, and irritable on the mornings they drank the caffeine-free coffee. Among light coffee drinkers, jittery feelings and stomach problems plagued them on mornings when they drank the highly caffeinated coffee.

The results of the Goldstein–Kaizer study were first published in the July 8, 1969, issue of Clinical Pharmacology and Therapeutics. The information was adapted by Edward M. Brecher for use in The Consumers Union Report on Licit and Illicit Drugs, 1972.

Babies born to women who consume extremely large amounts of caffeine during pregnancy have demonstrated delayed growth and problems with mental or physical development. As of 2005, doctors were advising pregnant women to keep their caffeine consumption within the bounds of a cup or two of coffee per day to ensure the good health of their babies. Pregnant women who have miscarried in the past are advised to avoid caffeine totally.

Reactions with Other Drugs or Substances

Caffeine cannot sober up someone who is drunk or save someone who is overdosing on a sedative. It can, however, alter the rate of absorption in the digestive system. Consuming caffeine in combination with drugs such as oral contraceptives and alcohol can delay the body's ability to rid itself of the caffeine.

Treatment for Habitual Users

Legally, caffeine is not regulated as a dangerously addictive substance. Yet, withdrawal from caffeine is documented in medical literature as a recognized set of symptoms. Physical and psychological dependence on coffee, for instance, tends to occur at rates of five or more cups per day. Many people who regularly consume caffeine and then suddenly stop will experience headaches, irritability, muscle aches, extreme tiredness, and impaired concentration.

A major symptom of quitting caffeine abruptly is a moderate to severe headache that generally begins within eighteen hours of the last dose. The feeling has been described as a fullness in the head that turns into a throbbing pain and is worsened by physical activity. Sadness and mild nausea are also reported by a quarter of those individuals who get the withdrawal headache. Those who chronically consume 500 to 600 mg of caffeine per day are more likely to experience withdrawal if they suddenly cease their habit. MSNBC.com reported that 13 percent of coffee addicts "were sick enough to lose time at work" when the source of their caffeine was taken away. Withdrawal symptoms can last as long as nine days.

In "Decreasing Your Caffeine Intake," registered dietician Karen Schroeder advises users who want to cut back on their caffeine intake to do so gradually. "Decreasing over a period of time" rather than going "cold turkey" may help minimize the symptoms of withdrawal. For starters, Schroeder suggests "mixing half regular and half decaffeinated coffee" or brewing tea "for a shorter time," since "a one-minute brew contains about half of the caffeine that a three-minute brew contains."


Consequences

As of 2005, there was no evidence that caffeine use alone was linked to the socially damaging behaviors that characterize drugs of abuse. Kim noted, however, that students who consume large amounts of caffeine to "enhance mental capacity" should be cautioned. Excessive caffeine consumption may actually bring on "symptoms unfavorable to studying, such as restlessness, anxiety, and heart palpitations. The student may struggle and would have better study habits without the caffeine."

The Law

There are no legal consequences for caffeine sale, use, or possession, since caffeine is not a scheduled substance. In 1997, the U.S. Food and Drug Administration (FDA) required labeling of the caffeine content of foods and drinks. Soft drink manufacturers are allowed to add a maximum of 6 milligrams of caffeine per ounce of beverage, which adds up to a limit of 72 milligrams per 12-ounce serving. Coffee and tea, containing caffeine naturally rather than as an additive, are not regulated for caffeine content.

For More Information

Books

Braun, Stephen. Buzz: The Science and Lore of Alcohol and Caffeine. New York: Oxford University Press, 1996.

Brecher, Edward M., and others. The Consumers Union Report on Licit and Illicit Drugs. Boston: Little Brown & Co., 1972.

Gahlinger, Paul M. Illegal Drugs: A Complete Guide to Their History, Chemistry, Use, and Abuse. Las Vegas, NV: Sagebrush Press, 2001.

Kuhn, Cynthia, Scott Swartzwelder, Wilkie Wilson, and others. Buzzed: The Straight Facts about the Most Used and Abused Drugs from Alcohol to Ecstasy, 2nd ed. New York: W.W. Norton, 2003.

Pendergrast, Mark. Uncommon Grounds. New York: Basic Books, 1999.

Weil, Andrew, and Winifred Rosen. From Chocolate to Morphine. New York: Houghton Mifflin, 1993, rev. 2004.

Weinberg, Bennett Alan, and Bonnie K. Bealer. The World of Caffeine: The Science and Culture of the World's Most Popular Drug. New York: Routledge, 2001.

Periodicals

Kim, Jennie. "The Buzz on Caffeine." The Hoya (February 8, 2000).

Morris, Ruth. "America's Bottomless Cup." Life (January 14, 2005): pp. 4-9.

Reid, T. R. "Caffeine." National Geographic (January, 2005): pp. 3-33.

Sparano, Nicole. "Is the Combination of Ibuprofen Plus Caffeine Effective for the Treatment of Tension-type Headache?" Journal of Family Practice (January, 2001): pp. 312-319.

Web Sites

"Coffee Kids." Coffee Kids: Grounds for Hope.http://www.coffeekids.org/ (accessed June 30, 2005).

Cohen, Elizabeth. "Energy Drinks Pack a Punch, But Is It Too Much?" CNN.com/HEALTH, May 29, 2001. http://archives.cnn.com/2001/HEALTH/diet.fitness/05/29/energy.drinks.02/index.html (accessed June 30, 2005).

Kagan, Daryn. "Dr. Sanjay Gupta: Caffeine Hidden in Many Foods." CNN.com/HEALTH, June 27, 2003. http://www.cnn.com/2003/HEALTH/diet.fitness/06/27/otsc.gupta/index.html (accessed June 30, 2005).

Schroeder, Karen. "Decreasing Your Caffeine Intake." St. John Health.http://www.stjohn.org/healthinfolib/ (accessed June 30, 2005).

"Tea and Caffeine." Holy Mountain Trading Company.http://www.holymtn.com/tea/caffeine.htm (accessed June 30, 2005).

"Too Much Caffeine." Information for Health Professionals: Medsafe Prescriber Update Articles, August 1999. http://www.medsafe.govt.nz/profs/PUarticles/caffeine.htm (accessed June 30, 2005).

"Yes, You Really Do Need That Coffee." MSNBC.com, September 30, 2004. http://www.msnbc.msn.com/id/6140162/ (accessed June 30, 2005).

See also: Amphetamines; Ephedra; Herbal Drugs

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"Caffeine." U*X*L Encyclopedia of Drugs and Addictive Substances. . Encyclopedia.com. 12 Oct. 2018 <http://www.encyclopedia.com>.

"Caffeine." U*X*L Encyclopedia of Drugs and Addictive Substances. . Encyclopedia.com. (October 12, 2018). http://www.encyclopedia.com/medicine/encyclopedias-almanacs-transcripts-and-maps/caffeine-4

"Caffeine." U*X*L Encyclopedia of Drugs and Addictive Substances. . Retrieved October 12, 2018 from Encyclopedia.com: http://www.encyclopedia.com/medicine/encyclopedias-almanacs-transcripts-and-maps/caffeine-4

Learn more about citation styles

Citation styles

Encyclopedia.com gives you the ability to cite reference entries and articles according to common styles from the Modern Language Association (MLA), The Chicago Manual of Style, and the American Psychological Association (APA).

Within the “Cite this article” tool, pick a style to see how all available information looks when formatted according to that style. Then, copy and paste the text into your bibliography or works cited list.

Because each style has its own formatting nuances that evolve over time and not all information is available for every reference entry or article, Encyclopedia.com cannot guarantee each citation it generates. Therefore, it’s best to use Encyclopedia.com citations as a starting point before checking the style against your school or publication’s requirements and the most-recent information available at these sites:

Modern Language Association

http://www.mla.org/style

The Chicago Manual of Style

http://www.chicagomanualofstyle.org/tools_citationguide.html

American Psychological Association

http://apastyle.apa.org/

Notes:
  • Most online reference entries and articles do not have page numbers. Therefore, that information is unavailable for most Encyclopedia.com content. However, the date of retrieval is often important. Refer to each style’s convention regarding the best way to format page numbers and retrieval dates.
  • In addition to the MLA, Chicago, and APA styles, your school, university, publication, or institution may have its own requirements for citations. Therefore, be sure to refer to those guidelines when editing your bibliography or works cited list.

Caffeine

Caffeine

Caffeine is the world's best-known stimulant. Popular beverages such as coffee, tea, and cola-based soft drinks all contain significant amounts of caffeine, as do the cacao bean, the chief ingredient in chocolate products, and guarana, the South American root extract used in many forms. When the use of caffeine as a component of many popular analgesics is factored, or when consumed in a pure-form stimulant such as a pill, there is no question that caffeine is also the most-consumed stimulant in the world. It is believed that more than 95% of the adult population of the United States consumes caffeinated products of one form or another. Caffeine is generally believed to be mildly addictive.

Caffeine is classified as a stimulant because when consumed in even small amounts, it will stimulate the central nervous system, the cardiac muscle (causing an increased heart rate), and the respiratory system. Caffeine will delay the onset of fatigue and it is a strong diuretic.

Caffeine is chemically defined in the class of substances known as alkaloids, nitrogen-based compounds that are typically found in plants. Alkaloids produce a pharmacological effect on the human body when consumed; cocaine, nicotine, and ephedrine are well-known examples of alkaloids.

The impact of caffeine on the body's metabolism first occurs with respect to the substance important to the transfer of energy within the body: adenosine. When consumed, caffeine blocks the operation of adenosine, and as a result the body produces epinephrine (adrenaline), which quickly causes a higher heart rate, increased blood pressure, and greater blood flow.

Athletes who are training or competing in anaerobic disciplines such as ice hockey or track and field events often consume caffeine (usually in the form of coffee or a sports supplement) to acquire a feeling of alertness and an ability to respond more quickly to the circumstances of competition. The actual effect of caffeine on performance for these sports may be more a psychological dependence on the belief that the caffeine stimulates more effective performance.

Caffeine has a proven positive effect on the function of the body in endurance sports, where the it relies primarily on its aerobic system to provide the requisite energy to compete. The ingestion of caffeine will increase the level of circulating fatty acids in the bloodstream, which permits these fat stores to be oxidized, or burned, as fuel. Accessing these fatty acids as fuel means that the body's stores of energy (known as glycogen), created through the processes that convert it from food carbohydrates, will not be exhausted in long competition. Marathon runners, long-distance cyclists, and cross-country skiers have been established as prime beneficiaries of caffeine when it is consumed approximately one hour before competition.

The effect of caffeine on the conversion of fatty acids to energy is further enhanced if the athlete is not a regular coffee drinker or does not consume caffeine products. In an alternative to the pre-competition consumption of caffeine by endurance athletes, further research has demonstrated the efficacy of caffeine in sports drinks. The carbohydrates in the caffeine-enhanced sport drinks were found to be absorbed by the body at a rate 26% faster than the rate achieved without caffeine. The ability of the body to utilize this portable energy source effectively saved bodily stores of energy.

Caffeine is considered an illegal, performance-enhancing substance in Olympic competition only if found in an athlete's system in levels in excess of 12 mcg/ml (micrograms/milliliter)—an amount that is the rough equivalent to the caffeine contained in eight to ten 6-oz (175 ml) cups of coffee—consumed within two hours of testing. In 2004, the World Anti-Doping Agency (WADA) removed caffeine from its list of prohibited substances. It is unlikely that an athlete could ingest caffeine in excess of the Olympic standard without causing an adverse impact upon the body's renal (kidney) and urinary systems, as the diuretic impact of high levels of caffeine will reduce hydration and stimulate urine production.

Caffeine withdrawal is a general description of the physical symptoms noted in persons who reduce the amount of caffeine that they consume. Excessive caffeine consumption reduces the system's resistance to the effects of caffeine, meaning more will be required to achieve the desired effect. Typical withdrawal will cause significant headaches, irritability, reduced sleep or insomnia, stomach upset, and cardiac arrhythmia.

A toxic level of caffeine is the equivalent to the consumption of between 50 and 150 6-oz (175 ml) cups of coffee. There is a well-established connection in caffeine research between the ingestion of caffeine and a loss of calcium density in bones, which can lead to the onset of osteoporosis, a condition whereby the bones become brittle and more prone to fracture.

see also Ephedra; Free fatty acids in the blood; Glycogen depletion; Stimulants.

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"Caffeine." World of Sports Science. . Encyclopedia.com. 12 Oct. 2018 <http://www.encyclopedia.com>.

"Caffeine." World of Sports Science. . Encyclopedia.com. (October 12, 2018). http://www.encyclopedia.com/sports/sports-fitness-recreation-and-leisure-magazines/caffeine

"Caffeine." World of Sports Science. . Retrieved October 12, 2018 from Encyclopedia.com: http://www.encyclopedia.com/sports/sports-fitness-recreation-and-leisure-magazines/caffeine

Learn more about citation styles

Citation styles

Encyclopedia.com gives you the ability to cite reference entries and articles according to common styles from the Modern Language Association (MLA), The Chicago Manual of Style, and the American Psychological Association (APA).

Within the “Cite this article” tool, pick a style to see how all available information looks when formatted according to that style. Then, copy and paste the text into your bibliography or works cited list.

Because each style has its own formatting nuances that evolve over time and not all information is available for every reference entry or article, Encyclopedia.com cannot guarantee each citation it generates. Therefore, it’s best to use Encyclopedia.com citations as a starting point before checking the style against your school or publication’s requirements and the most-recent information available at these sites:

Modern Language Association

http://www.mla.org/style

The Chicago Manual of Style

http://www.chicagomanualofstyle.org/tools_citationguide.html

American Psychological Association

http://apastyle.apa.org/

Notes:
  • Most online reference entries and articles do not have page numbers. Therefore, that information is unavailable for most Encyclopedia.com content. However, the date of retrieval is often important. Refer to each style’s convention regarding the best way to format page numbers and retrieval dates.
  • In addition to the MLA, Chicago, and APA styles, your school, university, publication, or institution may have its own requirements for citations. Therefore, be sure to refer to those guidelines when editing your bibliography or works cited list.

Caffeine

CHAPTER 9
CAFFEINE

As Americans sit down to their morning cups of coffee or tea or drink a cola, few think about the fact that they are taking a drug. A drug is any substance that affects the mood or the state and function of the body. According to this definition, the caffeine in many of our favorite beverages is a drug.

SOURCES OF CAFFEINE

Caffeine occurs naturally in the seeds, leaves, or fruits of more than sixty-three plant species throughout the world. The primary sources available in the United States, however, are coffee, tea, cacao (cocoa), and kola (cola) plants. These are grown and produced in tropical locations and shipped all over the world. Two other plants, maté and guarana, are primarily grown and consumed in South America as yerba maté and guarana bars and drinks (soda drinks or brewed hot drinks).

Table 9.1 lists the four major sources of caffeine, the parts of the plants that are consumed, and the locations in which the plants are grown. Of the three species of coffee, coffea arabica L. accounts for about three-quarters of all coffee consumption. Spices and other substances, such as vanilla and chocolate, can be added to make flavored coffees.

The three major tea types (green, oolong, and black) all come from the same species of plant; differences in flavor and color are a result of how the tea leaves are processed. For green tea, the leaves are steamed and dried. For oolong tea, the steamed leaves are partly fermented before they are dried. And for black tea, the steamed leaves are completely fermented before they are dried. As with coffee, spices and other flavorings can also be added to vary the taste of tea.

There are many products on the market today that are called "teas" even though they do not contain tea leaves. Virtually any beverage prepared by steeping substances in hot or boiling water is popularly called a tea. Herbal teas do not contain tea leaves or caffeine.

Varying Amounts of Caffeine

Not all plants contain equal concentrations of caffeine. Different methods of processing and brewing can also affect the amount of caffeine per cup or glass of a beverage. When calculating the amount of caffeine per cup or glass, a person must keep in mind the size of the cup or glass, and whether he or she dilutes coffee or tea with another substance, such as milk.

Of caffeinated drinks, coffee contains the highest concentration of caffeine. (See Table 9.2.) The way it is prepared, however, can change the amount of caffeine it contains. In general, coffee made in a drip-style coffee maker is highest in caffeine content. A six-ounce cup of coffee made by the drip method contains between 110-150 milligrams (mg) of caffeine; percolated coffee contains 64-124 mg of caffeine; and instant coffee contains 40-108 mg. Tea has significantly less caffeine than coffee, but the longer it is allowed to steep, the higher the caffeine concentration. A one-minute brew for a six-ounce cup of tea contains between thirty-five and forty-six mg of caffeine; a three-minute brew contains twenty to forty-six mg of caffeine. A hot cocoa mix typically contains six mg of caffeine. Both cocoa and cola drinks generally have lower levels of caffeine ounce per ounce than tea and coffee. However, cocoa contains large amounts of theobromine, a chemical related to caffeine that has the same stimulating effect.

Consumers should be aware that many popular over-the-counter (OTC, or nonprescription) medications contain caffeine. Caffeine is used in some OTC and prescription pain relievers because some studies have shown that caffeine increases their effectiveness. Caffeine is also a major ingredient in most preparations to help individuals stay awake and in OTC weight-control products.

Plant Species name Part of plant Major cultivation locations
CoffeeCoffea arabiaca L.Seeds (beans)Brazil, Columbia, Indonesia, Ethiopia, Kenya, Jamaica
Coffea robusta
Coffea liberica
TeaCamellia sinensisLeaves, budsIndia, China
Cacao (cocoa)Theobroma cacaoSeeds (beans)West Africa, Brazil
KolaCola acuminata S.Seeds (nuts)West Afrcia
Cola nitida
Source Caffeine content
Coffee, grande (16 oz) Starbucks550 mg
Caffe mocha, tall (12 oz.) Starbucks35 mg
Double espresso (2 oz)45-100 mg
Brewed coffee (1 cup)60-120 mg
Instant coffee (1cup)70 mg
Decaf coffee (1 cup)1-5 mg
Tea (1 cup)40 mg
Dark chocolate (1 oz)20 mg
Milk chocolate (1 oz)6 mg
Coca-Cola Classic (12 oz)34 mg
Diet Coke (12 oz)45 mg
NoDoz, regular strength (1 tablet)100 mg
Excedrin (2 tablets)130 mg
Mountain Dew (12 oz)55 mg
Anacin (2 tablets)65 mg
Over-the-counter weight-control aids140-200 mg

HOW MUCH CAFFEINE DO WE CONSUME?

Table 3.2 in Chapter 3 shows the per capita consumption of beverages: milk, tea, coffee, bottled water, carbonated soft drinks, fruit juices and fruit drinks, canned iced tea, and vegetable juices. Consumption of carbonated soft drinks generally rose between 1966 and the early 1990s and then leveled off somewhat. Most carbonated soft drinks contain caffeine. Coffee consumption was relatively stable from 1966 through 1976, dropped sharply in 1977, and has stayed somewhat consistent since then with the lowest level of consumption in the mid-1990s. In 2003 coffee consumption was 24.3 gallons per person.

Tea consumption rose somewhat steadily from 1966 through the mid-1970s, somewhat stabilized until 1990, and then rose sharply in the early-to-mid-1990s to somewhat stabilize again. In the mid-1990s, when coffee consumption was down somewhat, tea consumption was up somewhat. In 2003 tea consumption was 7.6 gallons per person.

The average daily intake of caffeine among consumers in the United States is about 280 mg, which is equal to about three cups of coffee or about seven twelve-ounce glasses of a cola beverage (L. M. Juliano and R. R. Griffiths, "A Critical Review of Caffeine Withdrawal: Empirical Validation of Symptoms and Signs, Incidence, Severity, and Associated Features," Psychopharmacology, vol. 176, 2004).

Results of a study published in 2001 (Janet Brown et al., "Misclassification of Exposure: Coffee as a Surrogate for Caffeine Intake," American Journal of Epidemiology, no. 153) show that the four main sources of caffeine for people aged thirty to seventy-five living in southern Ontario, Canada, were brewed coffee, instant coffee, regular tea, and cola soft drinks. Brewed coffee was the main source of caffeine, while tea and cola soft drinks ranked second or third, depending on age. Cola drinks ranked second for those aged thirty to forty-four, and tea ranked second for those aged forty-five to seventy-five. Men had a higher caffeine intake than women, and those aged forty-five to fifty-nine had a higher caffeine intake than younger persons.

Results of a study on beverage caffeine intake in U.S. consumers (C. A. Knight et al., Food and Chemical Toxicology, vol. 42, no. 12, December 2004) were some-what consistent with the Ontario study. Research results revealed that children and young adults up to age twenty-four consumed most of their caffeine in carbonated soft drinks. Consumption of coffee generally did not begin until age fifteen, but children as young as one year old consumed tea. People ages twenty-five and older consumed most of their caffeine in coffee, with carbonated soft drinks a second choice, and tea in third place. When people reached fifty years of age or so, tea became their second-largest source of caffeine, with carbonated soft drinks their third. This "switch" between tea and soft drinks remained throughout the rest of their lives.

The Ontario study also showed that caffeine intake is usually underestimated because people often report only their coffee intake and omit caffeine from other sources. The results of this study showed an average intake of caffeine for subgroups of these Ontario residents to range from a low of 288 mg per day for women ages thirty to forty-four to a high of 426 mg per day for men ages forty-five to fifty-nine.

Coffee remains the major source of caffeine for adults. According to the National Coffee Association's 2003 National Coffee Drinking Trends survey, 51% of the adult population drinks coffee everyday, representing 108.3 million coffee drinkers. Another 28% of the population, or 58.3 million adults, drinks coffee occasionally.

Only a small percentage of eighteen-to-twenty-four-year-olds consumed coffee in 2003—just 7% as estimated by the National Coffee Association. High levels of unemployment are correlated with lower levels of coffee drinking; this age group had the highest level of unemployment of all adults in 2003.

PHYSICAL EFFECTS OF CAFFEINE

Caffeine is classified as a stimulant because it increases the activity of the cardiovascular system, digestive system, and sympathetic nervous system (that which generally mobilizes the body for greater activity), and produces a sense of alertness in the brain. It also has a mild diuretic effect, eliminating water from the body by increasing urination. In moderate amounts, it can increase the ability to work longer and concentrate better. Too much caffeine, however, can produce nervousness, anxiety, irritability, and sleeplessness.

Because it gives athletes quicker reaction and longer endurance times, caffeine is a drug for which Olympic competitors are tested. If more than a small to moderate amount of caffeine (the amount in a few cups of coffee) is found in the blood, an athlete can be disqualified from the Olympic Games and other international competitions.

Many caffeine-producing plants also contain related stimulants known as methylxanthines, two of which are theophylline and theobromine. Theophylline is used in prescription drugs to treat chronic lung diseases such as asthma and emphysema. Theobromine is a weaker stimulant than caffeine, but it is more abundant in cocoa beans than is caffeine. Part of the stimulating effect of chocolate and cocoa is probably due to theobromine.

The fact that caffeine increases alertness has led to the myth that a strong cup of coffee will help to sober up someone who is drunk, but caffeine does not counteract the effects of alcohol.

How Caffeine Is Metabolized

In its pure state, caffeine is a bitter white powder that looks something like cornstarch. It is a member of the purine family of compounds. When purines are broken down in the body, they form a chemical called xanthine. The liver converts xanthine to uric acid, a metabolic waste product.

Caffeine dissolves in water, and it is rapidly and completely absorbed into the blood after ingestion. It takes from four to twelve hours to be eliminated completely from the body. Therefore, drinking coffee, tea, or caffeine-containing soft drinks several times a day can result in a large amount of caffeine in the body.

Two other purines, adenine and guanine, play a major role in human genetics and cell function. One of their by-products, adenosine, participates in the supply of energy to cells and helps regulate body processes such as the transmission of signals by nerves. In addition, adenosine can

  • Promote sleepiness.
  • Dilate blood vessels.
  • Reduce the contractions of the stomach and intestines.
  • Prevent seizures.
  • Slow the reaction to stress.
  • Lower the heart rate, blood pressure, and body temperature.

To perform these functions, adenosine inhibits the release of neurotransmitters (chemicals that carry messages from one nerve cell to another) by binding to specific receptors on a cell's surface. The structure of caffeine and its by-products is chemically similar to that of adenosine, which allows caffeine to bind to the same receptor sites, blocking adenosine and preventing it from taking effect. The effects of caffeine are the result of this blocking of the "slowing" effects of adenosine and explain why ingesting large amounts of caffeine may result in the "caffeine jitters."

IS CAFFEINE ADDICTIVE?

The question of whether caffeine is addictive has been debated for decades. Some medical experts believe it is mildly addictive because it fits the criteria for addiction: dependence and tolerance. In "Clinical Pharmacology of Caffeine" (Annual Review of Medicine, 1990), Neal L. Benowitz observed, "Minor criteria for addiction liability include the development of tolerance, physical dependence, and recurrent intense desire for the drug, all of which are characteristic of regular caffeine consumers. Thus, there is a group of coffee drinkers who appear to be addicted to caffeine, although the extent of caffeine addiction in the population is unknown."

While caffeine is both psychoactive (mood altering) and addictive, it is not intoxicating. No one gets drunk or "high" on caffeine, although it can produce anxiety and sleeplessness.

However, results of a 1999 study, "Are We Dependent upon Coffee and Caffeine? A Review on Human and Animal Data" (Neuroscience and Biobehavioral Reviews), show that complete tolerance to many of the effects of caffeine on the central nervous system does not occur. Additionally, average daily doses of caffeine do not act on brain structures related to reward, motivation, and addiction as do "hard" drugs such as cocaine and amphetamines.

HEALTH EFFECTS

One major side effect of consuming large quantities of coffee, tea, soft drinks, and chocolate is a nervous feeling or jitters. In general, the more caffeine that is consumed, the more likely the person is to suffer these side effects. For some people, however, even a minor amount of caffeine can disrupt their sleeping patterns, cause their hands to shake, or create anxiety.

The physical effects of caffeine in the body are fairly well understood, but studies attempting to link caffeine to different diseases have been inconclusive. For example, scientists know that caffeine stimulates the central nervous system, resulting in increased alertness and mood elevation. However, for persons in good general health, studies have not shown any link between drinking coffee or tea and suffering from a nervous disorder, other than the temporary side effects discussed above.

Caffeine does raise blood pressure. Some people develop a tolerance to this effect, and the blood pressure soon returns to its normal level. However, some do not develop this tolerance. Caffeine causes a persistent rise in blood pressure among some regular consumers, even when their daily intake is moderate (W. R. Lovall et al., "Blood Pressure Response to Caffeine Shows Incomplete Tolerance after Short-Term Regular Consumption," Hypertension, vol. 43, no. 4, April 2004). In "Critical Review of Dietary Caffeine and Blood Pressure: A Relationship That Should Be Taken More Seriously," J. E. James contends that caffeine use could account for 14% of coronary heart disease deaths and 20% of stroke deaths (Psychosomatic Medicine, vol. 66, no. 1, January-February 2004).

Coffee has also been suspected of increasing cholesterol levels in the blood, but research data are some-what contradictory. Results from a Norwegian study found that drinking filtered coffee was not associated with high cholesterol levels, but that consumption of boiled coffee promoted increased plasma concentration of cholesterol and was thus associated with an elevated risk for cardiovascular disease (T. Ranheim and B. Halvorsen, "Coffee Consumption and Human Health—Beneficial or Detrimental?" Molecular Nutrition and Food Research, vol. 49, no. 3, March 2005). In contrast, P. Happonen et al. determined that brewing method does not make a difference, and concluded from their data that heavy coffee consumption increases the short-term risk of heart attack and death ("Coffee Drinking Is Dose-Dependently Related to the Risk of Acute Coronary Events in Middle-Aged Men," Journal of Nutrition, vol. 134, no. 9, September 2004). Moreover, results of a Nigerian study conducted by A. J. Onuegbu and E. O. Agbedana suggest that shortterm consumption of coffee may increase the total serum cholesterol and LDL (bad) cholesterol levels ("The Effects of Coffee Consumption on Serum Lipids and Lipoprotein in Healthy Individuals," African Journal of Medicine and Medical Sciences, vol. 30, no. 1-2, March–June 2001).

Caffeine Overdose

It is possible to overdose on caffeine. Symptoms of an overdose include hyperventilation (rapid, deep breathing), rapid heartbeat, atrial heart fibrillation (twitching; beating unevenly), convulsions, and imbalances in the body's levels of potassium, sugar, and other blood chemicals. The overdose amount differs from person to person and depends on body weight, metabolic rate, and usual intake of caffeine (tolerance).

Fatal caffeine overdoses are very rare, but they can occur. Most are either suicide attempts or accidental overuse of caffeine tablets. An average-sized adult would have to consume about 5,000 milligrams (five grams) of caffeine—about fifty cups of normal-strength coffee—to get a fatal dose, and the cups would have to be drunk in rapid succession. In children, because of their smaller body mass and differences in metabolizing caffeine, a much smaller dose could be lethal.

Is There a Link to Cancer?

Results of studies to determine the links (if any) between caffeine and various types of cancer have been contradictory. For every study that gives evidence of a possible link, another study finds no evidence of a link. Results of laboratory studies have shown that caffeine can change the cells of bacteria, plants, insects, and humans in the laboratory, but results of epidemiological studies have not shown that caffeine causes cancerous cell development in generally healthy people. In a 1997 report (Nutrition and the Prevention of Cancer: A Global Perspective), the American Institute of Cancer Research in Washington, D.C., and the World Cancer Fund in London stated that "most evidence suggests that regular consumption of coffee and/or tea has no significant relationship with the risk of cancer of any site."

Results of a 2005 Harvard study, which used large data sets from the Nurses' Health Study (women) and the Health Professionals' Follow-up Study (men), support the findings reported in the previous paragraph, in that consumption of caffeinated coffee or tea, or caffeine from other sources, was not associated with the incidence of colon or rectal cancer. Conversely, regular consumption of decaffeinated coffee was associated with a reduced incidence of rectal cancer (K. B. Michels et al., "Coffee, Tea, and Caffeine Consumption and Incidence of Colon and Rectal Cancer," Journal of the National Cancer Institute, vol. 97, no. 4, February 2005).

Caffeine and Pregnancy

While heavy caffeine use has been suspected of contributing to miscarriages, some studies have given conflicting results and failed to establish a definite link (L. B. Signorello and J. K. McLaughlin, "Maternal Caffeine Consumption and Spontaneous Abortion: A Review of

Substance Interaction
AlcoholSlows down the metabolism of caffeine
TobaccoSpeeds up the metabolism of caffeine
Birth control pillsSlow down the metabolism of caffeine
Monoamine oxidase (MAO) inhibitors (used to treat depression) and some tranquilizersMay have reduced effectiveness due to caffeine's stimulating effects
DecongestantsHave effects similar to caffeine, so jitteriness, insomnia, or irritability may be made worse

the Epidemiologic Evidence," Epidemiology, vol. 15, no. 2, March 2004).

The U.S. Food and Drug Administration (FDA) advises pregnant women to limit or eliminate their intake of caffeine. The substances that an expectant mother eats or drinks can be passed through the bloodstream to her unborn baby, and a mother who drinks large amounts of caffeine may produce a baby who shows signs of caffeine jitters. Nursing mothers can also pass caffeine to their babies through breast milk, leading to sleep disruptions and irritability.

Interactions with Other Drugs

Caffeine may also interact with prescription and OTC drugs. In some cases, a drug may have side effects similar to those of caffeine, so even a small amount of coffee, tea, or cola may cause jitteriness or disturb sleep. In other cases, caffeine may reduce or heighten the effectiveness of medications. In addition, alcohol and tobacco affect the metabolism of caffeine in the body, causing it either to leave the body more rapidly or to remain in the bloodstream for a longer time. (See Table 9.3.) People who drink a lot of caffeinated beverages should discuss with their doctors the effects caffeine might have on any medications they are taking.

Possible Health Benefits

Caffeine's bronchodilator effect of opening the air-ways can be beneficial to people suffering from acute bronchial asthma. Caffeine acts as an analgesic (pain killer) and, when combined with ibuprofen, can bring faster and longer lasting relief from tension headaches. It is often prescribed for migraine headaches. Drinking two cups of coffee before breakfast has helped individuals suffering from dizziness and other effects caused by abnormally low blood pressure.

DECAFFEINATION

People who are sensitive to caffeine or those who want to moderate their caffeine intake can still enjoy their favorite beverages in decaffeinated forms. Decaffeination removes almost all the caffeine (about 97%) from coffee or tea. There are three common methods of decaffeination.

  • The direct method uses methylene chloride, which dissolves caffeine, to remove caffeine from green coffee beans and moist tea leaves. Then a further process removes the methylene chloride from the product.
  • The water method uses water to dissolve the caffeine from steamed coffee beans or tea leaves. Then the caffeine is removed from the water by using methylene chloride, and the decaffeinated water is added back to the coffee or tea to enhance flavor. The beans or leaves are steamed again to remove any methylene chloride remaining.
  • The carbon dioxide method, which is the newest, uses carbon dioxide to remove caffeine. This process leaves in more flavor than the other two methods.

Methylene chloride, in its inhaled form, is known to cause cancer in laboratory animals. When methylene chloride is diluted in their drinking water, however, the laboratory animals do not develop cancer. The FDA has analyzed decaffeinated coffee made through the direct method and found that so little methylene chloride is left in the final product that any risk of it causing cancer is remote. The amount of methylene chloride in the finished product is less than that found in the air on a smoggy day.

Some people find that decaffeinated coffee lacks some of the flavor of regular coffee. Using fresh-ground or flavored decaffeinated coffee beans may help brew a better-tasting pot of coffee. Using half regular coffee and half decaffeinated coffee can also help cut down caffeine intake, as can simply drinking fewer caffeineladen drinks per day. Hot chocolate, hot apple cider, and herbal teas make good low-caffeine or caffeine-free substitutes for those wanting to limit their caffeine intake.

What Do They Do with the Caffeine They Take Out?

The caffeine removed from coffee and tea is a useful by-product. It can be used in medications or added to soft drinks to increase their caffeine content. Some is processed into theophylline, which is used in medications for asthma and emphysema.

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"Caffeine." Information Plus(R) Reference Series Fall 2005. . Encyclopedia.com. 12 Oct. 2018 <http://www.encyclopedia.com>.

"Caffeine." Information Plus(R) Reference Series Fall 2005. . Encyclopedia.com. (October 12, 2018). http://www.encyclopedia.com/reference/encyclopedias-almanacs-transcripts-and-maps/caffeine

"Caffeine." Information Plus(R) Reference Series Fall 2005. . Retrieved October 12, 2018 from Encyclopedia.com: http://www.encyclopedia.com/reference/encyclopedias-almanacs-transcripts-and-maps/caffeine

Learn more about citation styles

Citation styles

Encyclopedia.com gives you the ability to cite reference entries and articles according to common styles from the Modern Language Association (MLA), The Chicago Manual of Style, and the American Psychological Association (APA).

Within the “Cite this article” tool, pick a style to see how all available information looks when formatted according to that style. Then, copy and paste the text into your bibliography or works cited list.

Because each style has its own formatting nuances that evolve over time and not all information is available for every reference entry or article, Encyclopedia.com cannot guarantee each citation it generates. Therefore, it’s best to use Encyclopedia.com citations as a starting point before checking the style against your school or publication’s requirements and the most-recent information available at these sites:

Modern Language Association

http://www.mla.org/style

The Chicago Manual of Style

http://www.chicagomanualofstyle.org/tools_citationguide.html

American Psychological Association

http://apastyle.apa.org/

Notes:
  • Most online reference entries and articles do not have page numbers. Therefore, that information is unavailable for most Encyclopedia.com content. However, the date of retrieval is often important. Refer to each style’s convention regarding the best way to format page numbers and retrieval dates.
  • In addition to the MLA, Chicago, and APA styles, your school, university, publication, or institution may have its own requirements for citations. Therefore, be sure to refer to those guidelines when editing your bibliography or works cited list.

Caffeine-Related Disorders

Caffeine-Related Disorders

Definition

Description

Causes and symptoms

Demographics

Diagnosis

Treatments

Prognosis

Prevention

Resources

Definition

Caffeine is a white, bitter crystalline alkaloid derived from coffee or tea. It belongs to a class of compounds called xanthines, its chemical formula being 1,3,7-trimethylxanthine. Caffeine is classified together with cocaine and amphetamines as an ana-leptic, or central nervous system stimulant. Coffee is the most abundant source of caffeine, although caffeine is also found in tea, cocoa, and cola beverages as well as in over-the-counter and prescription medications for pain relief.

In the clinician’s handbook for diagnosing mental disorders (the Diagnostic and Statistical Manual of Mental Disorders, known as the DSM-IV-TR), caffeine-related disorders are classified under the rubric of substance-related disorders. DSM-IV-TR specifies four caffeine-related disorders: caffeine intoxication, caffeine-induced anxiety disorder, caffeine-induced sleep disorder, and caffeine-related disorder not otherwise specified. A fifth, caffeine withdrawal, is listed under the heading of “Criteria Sets and Axes Provided for Further Study.”

Caffeine-related disorders are often unrecognized for a number of reasons:

  • Caffeine has a “low profile” as a drug of abuse. Consumption of drinks containing caffeine is unregulated by law and is nearly universal in the United States; one well-known textbook of pharmacology refers to caffeine as “the most widely used psychoactive drug in the world.” In many countries, coffee is a social lubricant as well as a stimulant; the “coffee break” is a common office ritual, and many people find it difficult to imagine eating a meal in a fine restaurant without having coffee at some point during the meal. It is estimated that 10-12 billion pounds of coffee are consumed worldwide each year.
  • People often underestimate the amount of caffeine they consume on a daily basis because they think of caffeine only in connection with coffee as a beverage. Tea, cocoa, and some types of soft drink, including root beer and orange soda as well as cola beverages, also contain significant amounts of caffeine. In one British case study, a teenager who was hospitalized with muscle weakness, nausea, vomiting, diarrhea, and weight loss was found to have caffeine intoxication caused by drinking 8 liters (about 2 gallons) of cola on a daily basis for the previous two years. She had been consuming over a gram of caffeine per day. Chocolate bars and coffee-flavored yogurt or ice cream are additional sources of measurable amounts of caffeine.
  • Caffeine has some legitimate medical uses in athletic training and in the relief of tension-type headaches. It is available in over-the-counter (OTC) preparations containing aspirin or acetaminophen for pain relief as well as in such OTC stimulants as NoDoz and Vivarin.
  • Caffeine is less likely to produce the same degree of physical or psychological dependence as other drugs of abuse. Few coffee or tea drinkers report loss of control over caffeine intake, or significant difficulty in reducing or stopping consumption of beverages and food items containing caffeine.
  • The symptoms of caffeine intoxication are easy to confuse with those of an anxiety disorder.

The DSM-TR-IV states that it is unclear as of 2000 whether the tolerance, withdrawal symptoms, and “some aspects of dependence on caffeine” seen in some people who drink large amounts of coffee “are associated with clinically significant impairment that meets the criteria for Substance Abuse or Substance Dependence.” On the other hand, a research team at Johns Hopkins regards caffeine as a model drug for understanding substance abuse and dependence. The team maintains that 9%-30% of caffeine consumers in the United States may be caffeine-dependent according to DSM criteria for substance dependency.

Description

Pharmacological aspects of caffeine

An outline of the effects of caffeine on the central nervous system (CNS) and other organ systems of the body may be helpful in understanding its potential for physical dependence. When a person drinks a beverage containing caffeine (or eats coffee-flavored ice cream), the caffeine is absorbed from the digestive tract without being broken down. It is rapidly distributed throughout the tissues of the body by means of the bloodstream. If a pregnant woman drinks a cup of coffee or tea, the caffeine in the drink will cross the placental barrier and enter the baby’s bloodstream.

When the caffeine reaches the brain , it increases the secretion of norepinephrine, a neurotransmitter that is associated with the so-called fight or flight stress response. The rise in norepinephrine levels and the increased activity of the neurons, or nerve cells, in many other areas of the brain helps to explain why the symptoms of caffeine intoxication resemble the symptoms of a panic attack.

The effects of caffeine are thought to occur as a result of competitive antagonism at adenosine receptors. Adenosine is a water-soluble compound of adenine and ribose; it functions to modulate the activities of nerve cells and produces a mild sedative effect when it activates certain types of adenosine receptors. Caffeine competes with adenosine to bind at these receptors and counteracts the sedative effects of the adenosine. If the person stops drinking coffee, the adenosine has no competition for activating its usual receptors and may produce a sedative effect that is experienced as fatigue or drowsiness.

Caffeine content of food items and OTC preparations

The caffeine content of various food items and medications is as follows:

  • brewed coffee, 8-oz cup: 135-150 mg
  • instant coffee, 8-oz cup: 95 mg.
  • powdered cappuccino beverage, 8-oz cup: 45-60 mg
  • tea brewed from leaves or bag, 8-oz cup: 50 mg
  • iced tea from mix, 8-oz glass: 25-45 mg
  • Snapple iced tea, 8-oz glass: 21 mg
  • Mountain Dew, 8-oz glass: 38 mg
  • Dr. Pepper, 8-oz. glass: 28 mg
  • diet cola, 8-oz glass: 31 mg
  • root beer, 8-oz glass: 16 mg
  • coffee ice cream, 8-oz serving: 60-85 mg
  • coffee yogurt, 8-oz serving: 45 mg.
  • dark chocolate candy bar, 1.5 oz: 31 mg
  • NoDoz, regular strength, 1 tablet: 100 mg
  • NoDoz, maximum strength, 1 tablet: 200 mg
  • Excedrin, 2 tablets: 130 mg

Caffeine can produce a range of physical symptoms following ingestion of as little as 100 mg, although amounts of 250 mg or higher are usually needed to produce symptoms that meet the criteria of caffeine intoxication.

Caffeine intoxication

To meet DSM-IV-TR criteria for caffeine intoxication, a person must develop five or more of the twelve symptoms identified, the symptoms must cause significant distress or impair the person’s social or occupational functioning; and the symptoms must not be caused by a medical disorder or better accounted for by an anxiety disorder or other mental disorder.

Because people develop tolerance to caffeine fairly quickly with habitual use, caffeine intoxication is most likely to occur in those who consume caffeine infrequently or who have recently increased their intake significantly.

Caffeine-induced anxiety and sleep disorders

DSM-IV-TR criteria for caffeine-induced anxiety and sleep disorders specify that the symptoms of anxiety and insomnia respectively must be more severe than the symptoms associated with caffeine intoxication. In addition, the anxiety or insomnia must be severe enough to require separate clinical attention.

Causes and symptoms

Causes

The immediate cause of caffeine intoxication and other caffeine-related disorders is consumption of an amount of caffeine sufficient to produce the symptoms specified by DSM-IV-TR as criteria for the disorder. The precise amount of caffeine necessary to produce symptoms varies from person to person depending on body size and degree of tolerance to caffeine. Tolerance of the stimulating effects of caffeine builds up rapidly in humans; mild withdrawal symptoms have been reported in persons who were drinking as little as one to two cups of coffee per day.

Some people may find it easier than others to consume large doses of caffeine because they are insensitive to its taste. Caffeine tastes bitter to most adults, which may serve to limit their consumption of coffee and other caffeinated beverages. Slightly more than 30% of the American population, however, has an inherited inability to taste caffeine.

Symptoms

The symptoms of caffeine intoxication include:

  • restlessness
  • nervousness
  • excitement
  • insomnia
  • flushed face
  • diuresis (increased urinary output)
  • gastrointestinal disturbance
  • muscle twitching
  • talking or thinking in a rambling manner
  • tachycardia (speeded-up heartbeat) or disturbances of heart rhythm.
  • periods of inexhaustibility
  • psychomotor agitation

People have reported ringing in the ears or seeing flashes of light at doses of caffeine above 250 mg. Profuse sweating and diarrhea have also been reported. Doses of caffeine higher than 10 g may produce respiratory failure, seizures, and eventually death.

Side effects and complications

High short-term consumption of caffeine can produce or worsen gastrointestinal problems, occasionally leading to peptic ulcers or hematemesis (vomiting blood).

In addition to the symptoms produced by high short-term doses, long-term consumption of caffeine has been associated with fertility problems and with bone loss in women leading to osteoporosis in old age. Some studies have found that pregnant women who consume more than 150 mg per day of caffeine have an increased risk of miscarriage and low birth weight babies, but the findings are complicated by the fact that most women who drink large amounts of coffee during pregnancy are also heavy smokers. Some researchers believe that long-term consumption of caffeine is implicated in cardiovascular diseases, but acknowledge that further research is required.

On the other hand, moderate doses of caffeine improve athletic performance as well as alertness. Caffeine in small doses can relieve tension headaches, and one study found that a combination of ibuprofen and caffeine was more effective in relieving tension headaches than either ibuprofen alone or a placebo. Coffee consumption also appears to lower the risk of alcoholic and nonalcoholic cirrhosis of the liver.

Drug interactions

Caffeine is often combined with aspirin or acetaminophen in over-the-counter and prescription analgesics (pain relievers). It can also be combined with ibuprofen. On the other hand, certain groups of drugs should not be combined with caffeine or taken with beverages containing caffeine. Oral contraceptives, cimetidine (Tagamet), mexiletine (Mexitil), and disulfiram (Antabuse) interfere with the breakdown of caffeine in the body. Caffeine interferes with the body’s absorption of iron, and with drugs that regulate heart rhythm, including quinidine and propranolol (Inderal). Caffeine may produce serious side effects when taken together with monoamine oxidase inhibitors or with certain decongestant medications.

Combinations of ephedra and caffeine have been used in weight-loss programs because they produce greater weight loss than can be achieved by caloric restriction alone. Major studies are underway as of 2001 at Harvard and Vanderbilt to determine the safety of these regimens.

Practitioners of homeopathy have traditionally advised patients not to drink beverages containing caffeine in the belief that caffeine “antidotes” homeopathic remedies. Contemporary homeopaths disagree on the antidoting effects of caffeine, observing that homeopathy is used widely and effectively in Europe and that Europeans tend to drink strong espresso coffee more frequently than Americans.

Demographics

The general population of the United States has a high level of caffeine consumption, with an average intake of 200mg per day. About 85% of the population uses caffeine in any given year. Among adults in the United States, about 30% consume 500 mg or more each day. These figures are lower, however, than the figures for Sweden, the United Kingdom, and other parts of Europe, where the average daily consumption of caffeine is 400 mg or higher. In developing countries, the average consumption of caffeine is much lower— about 50 mg per day.

In the United States, levels of caffeine consumption among all races and ethnic groups are related to age, with usage beginning in the late teens and rising until the early 30s. Caffeine consumption tapers off in adults over 40 and decreases in adults over 65. Caffeine intake is higher among males than among females in North America.

Diagnosis

Diagnosis of a caffeine-related disorder is usually based on the patient’s recent history, a physical examination, or laboratory analysis of body fluids. In addition to medical evidence, the examiner will rule out other mental disorders, particularly manic episodes, generalized anxiety disorder, panic disorder, amphetamine intoxication, or withdrawal from sedatives, tranquilizers, sleep medications, or nicotine . All of these disorders or syndromes may produce symptoms resembling those of caffeine intoxication. In most cases the temporal relationship of the symptoms to high levels of caffeine intake establishes the diagnosis.

In some cases, the examiner may consider the possibility of depression during the differential diagnosis, as many people with depression and eating disorders self-medicate with caffeine.

Treatments

Treatment of caffeine-related disorders involves lowering consumption levels or abstaining from beverages containing caffeine. Some people experience mild withdrawal symptoms that include headaches, irritability, and occasionally nausea, but these usually resolve quickly.

Caffeine consumption has the advantage of having relatively weak (compared to alcohol or cigarettes) social reinforcement, in the sense that one can easily choose a noncaffeinated or decaffeinated beverage in a restaurant or at a party without attracting comment. Thus physical dependence on caffeine is less complicated by the social factors that reinforce nicotine and other drug habits.

Prognosis

With the exception of acute episodes of caffein-ism, people recover from caffeine intoxication without great difficulty.

Prevention

Prevention of caffeine-related disorders requires awareness of the caffeine content of caffeinated beverages, OTC drugs, and other sources of caffeine; monitoring one’s daily intake; and substituting decaffeinated coffee, tea, or soft drinks for the caffeinated versions of these beverages.

KEY TERMS

Adenosine —A compound that serves to modulate the activities of nerve cells (neurons) and to produce a mild sedative effect when it activates certain types of adenosine receptors. Caffeine is thought to produce its stimulating effect by competing with adenosine for activation of these receptors.

Analeptic —A substance that acts as a stimulant of the central nervous system. Caffeine is classified as an analeptic.

Caffeinism —A disorder caused by ingesting very high doses of caffeine (10g or more per day) and characterized by seizures and respiratory failure.

Dependence —The adaptation of neurons and other physical processes to the use of a drug, followed by withdrawal symptoms when the drug is removed; physiological and/or psychological addiction.

Hematemesis —Vomiting blood. Hematemesis is a symptom that sometimes occurs with gastrointestinal ulcers made worse by high levels of caffeine consumption.

Norepinephrine —A catecholamine neurotransmitter that acts to constrict blood vessels, raise blood pressure, and dilate the bronchi of the respiratory system. Caffeine increases the secretion of norepinephrine.

Reinforcement —A term that refers to the ability of a drug or substance to produce effects that will make the user want to take it again.

Tolerance —Progressive decrease in the effectiveness of a drug with long-term use.

Withdrawal —Symptoms experienced by a person who has become physically dependent on a drug, experienced when the drug use is discontinued.

Xanthine —A class of crystalline nitrogenous compounds that includes caffeine, which is 1,3,7-trimethylxanthine.

Resources

BOOKS

American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders. 4th edition, text revised. Washington, DC: American Psychiatric Association, 2000.

“Anxiety Due to a Physical Disorder or a Substance.” Section 15, Chapter 187. In The Merck Manual of Diagnosis and Therapy, edited by Mark H. Beers, MD, and Robert Berkow, MD. Whitehouse Station, NJ: Merck Research Laboratories, 1999.

Murray, Michael, ND, and Joseph Pizzorno, ND. Encyclopedia of Natural Medicine. Rocklin, CA: Prima Publishing, 1991.

O’Brien, Charles P. “Drug Addiction and Drug Abuse.” Chapter 24 in Goodman & Gilman’s The Pharmacological Basis of Therapeutics, edited by J. G. Hardman and L. E. Limbird. 9th edition. New York and St. Louis, MO: McGraw-Hill, 1996.

Pelletier, Kenneth R., MD. “Naturopathic Medicine.” Chapter 7, in The Best Alternative Medicine. New York: Simon & Schuster, 2002.

PERIODICALS

Breslin, P. A. S., C. D. Tharp, and D. R. Reed. “Selective Taste Blindness to Caffeine and Sucrose Octa Acetate: Novel Bimodal Taste Distributions Unrelated to PROP and PTC.” American Journal of Human Genetics 69 (October 2001): 507.

“Caffeine Toxicity from Cola Consumption.” Internal Medicine Journal 31 (2001): 317–318.

Corrao, G. “Coffee, Caffeine, and the Risk of Liver Cirrhosis.” Annals of Epidemiology 11 (October 2001): 458–465.

De Valck, E., and R. Cluydts. “Slow-Release Caffeine as a Countermeasure to Driver Sleepiness Induced by Partial Sleep Deprivation.” Journal of Sleep Research 10 (September 2001): 203–209.

Diamond, S., T. K. Balm, and F. G. Freitag. “Ibuprofen Plus Caffeine in the Treatment of Tension-Type Headache.” Clinical Pharmacology and Therapeutics 68 (2000): 312–319.

Griffiths, R. R., and A. L. Chausmer. “Caffeine as a Model Drug of Dependence: Recent Developments in Understanding Caffeine Withdrawal, the Caffeine Dependence Syndrome, and Caffeine Negative Reinforcement.” Nihon Shinkei Seishin Yakurigaku Zasshi 20 (November 2000): 223–231.

MacFadyen, L., D. Eadie, and T. McGowan. “Community Pharmacists’ Experience of Over-the-Counter Medicine Misuse in Scotland.” Journal of Research in Social Health 121 (September 2001): 185–192.

Preboth, Monica. “Effect of Caffeine on Exercise Performance.” American Family Physician 61 (May 2000): 628.

Rapurl, P. B., J. C. Gallagher, H. K. Kinyarnu, and others. “Caffeine Intake Increases the Rate of Bone Loss in Elderly Women and Interacts with Vitamin D Receptor Genotypes.” American Journal of Clinical Nutrition 74 (2001): 694–700.

Rumpler, William, James Seale, Beverly Clevidence, and others. “Oolong Tea Increases Metabolic Rate and Fat Oxidation in Men.” Journal of Nutrition 131 (November 2001): 2848–2852.

Sardao, V. A., P. J. Oliveira, and A. J. Moreno. “Caffeine Enhances the Calcium-Dependent Cardiac Mitochon-drial Permeability Transition: Relevance for Caffeine Toxicity.” Toxicology and Applied Pharmacology 179 (February 2002): 50–56.

ORGANIZATIONS

American College of Sports Medicine. P. O. Box 1440, Indianapolis, IN 46206-1440. Telephone: (317) 637-9200.

American Dietetic Association. Telephone: (800) 877-1600. <www.eatright.org>.

Center for Science in the Public Interest (CSPI). <www.cspinet.org>.

Rebecca J. Frey, Ph.D.

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"Caffeine-Related Disorders." The Gale Encyclopedia of Mental Health. . Encyclopedia.com. 12 Oct. 2018 <http://www.encyclopedia.com>.

"Caffeine-Related Disorders." The Gale Encyclopedia of Mental Health. . Encyclopedia.com. (October 12, 2018). http://www.encyclopedia.com/medicine/encyclopedias-almanacs-transcripts-and-maps/caffeine-related-disorders

"Caffeine-Related Disorders." The Gale Encyclopedia of Mental Health. . Retrieved October 12, 2018 from Encyclopedia.com: http://www.encyclopedia.com/medicine/encyclopedias-almanacs-transcripts-and-maps/caffeine-related-disorders

Learn more about citation styles

Citation styles

Encyclopedia.com gives you the ability to cite reference entries and articles according to common styles from the Modern Language Association (MLA), The Chicago Manual of Style, and the American Psychological Association (APA).

Within the “Cite this article” tool, pick a style to see how all available information looks when formatted according to that style. Then, copy and paste the text into your bibliography or works cited list.

Because each style has its own formatting nuances that evolve over time and not all information is available for every reference entry or article, Encyclopedia.com cannot guarantee each citation it generates. Therefore, it’s best to use Encyclopedia.com citations as a starting point before checking the style against your school or publication’s requirements and the most-recent information available at these sites:

Modern Language Association

http://www.mla.org/style

The Chicago Manual of Style

http://www.chicagomanualofstyle.org/tools_citationguide.html

American Psychological Association

http://apastyle.apa.org/

Notes:
  • Most online reference entries and articles do not have page numbers. Therefore, that information is unavailable for most Encyclopedia.com content. However, the date of retrieval is often important. Refer to each style’s convention regarding the best way to format page numbers and retrieval dates.
  • In addition to the MLA, Chicago, and APA styles, your school, university, publication, or institution may have its own requirements for citations. Therefore, be sure to refer to those guidelines when editing your bibliography or works cited list.