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Causes and symptoms


Nutrition/dietetic concerns






Constipation is a symptom characterized by either having fewer than three bowel movements a week or having difficulty passing stools that are often hard, small, and dry.


Food in the process of being digested moves through the intestines in as a slurry or watery mush. In the small intestine, nutrients are absorbed from this material. After most of the nutrients have been absorbed, the material passes into the colon, or large intestine. Here much of the water in the slurry is absorbed back into the

bloodstream, and the remaining solid material is eliminated as waste or stool. Constipation occurs when too much water is removed from the slurry, and it becomes difficult or painful to eliminate the stool. The most common reason why too much water is removed is that the material stays too long in the colon.

The frequency of bowel movements varies greatly from person to person and is influenced by age, health, diet, and lifestyle. It is a common misperception that a daily bowel movement is necessary for health. This is not true. For some healthy people, it is normal to have three bowel movements a day, while other healthy people have only three a week. Determining whether an individual is constipated must start with knowing what frequency of bowel movements is normal for that person.


Constipation is a very common complaint. About 2% of Americans complain of frequent or constant constipation. In 2005, constipation accounted for about 2.5 million visits to the doctor. In the United States more black Americans report being constipated than white Americans. In Africa, the reverse is true, suggesting that diet plays a more important role than race in determining who develops constipation. This is also supported by the fact that very few Asians who eat an Asian diet report being constipated, while those who adopt a Western diet report constipation much more frequently. Complaints about constipation are more likely to come from women than from men and from people over age 65. Pregnant women are at higher risk to become constipated, as are people who have had surgery and who are taking narcotic painkillers.

Causes and symptoms

Constipation is not a disorder but a symptom of a health problem, like a fever or a cough. There are two general categories of constipation, idiopathic constipation, and functional constipation. Idiopathic means “of unknown origin.“Idiopathic constipation is constipation that arises from an unknown cause. It may be related to hormonal abnormalities, nerve, or muscle damage, or something physicians do not yet understand. Functional constipation occurs when the bowel is healthy, but constipation develops because of diet, lifestyle habits, psychological disorders, or abnormalities in the rectum or anus.

Symptoms of constipation may include:

  • bowel movements that occur less frequently than normal
  • straining to eliminate stools
  • small, hard, dry, painful, stools
  • a feeling of pressure in the rectum a feeling of abdominal fullness or bloating
  • leakage of small amounts of liquid stool. This occurs when there is a blockage or impaction and the colon is abnormally stretched

Constipation has many causes. The most common cause in the United States is poor diet. A diet that increases the chances of developing constipation is one that is high in meat, dairy products, and refined sugar and low in dietary fiber Other causes include:

  • little physical exercise. This is a particular problem in the elderly
  • medications, especially narcotic drugs used to treat pain, but also antidepressants, antacids containing


Anus —The opening from the rectum to the outside of the body through which stools pass. The opening and closing of the anus is controlled by a strong ring of muscles under somewhat voluntary control.

Dietary fiber —Also known as roughage or bulk. Insoluble fiber moves through the digestive system almost undigested and gives bulk to stools. Soluble fiber dissolves in water and helps keep stools soft.

Idiopathic —Occurring from unknown causes.

Laxative —A substance that stimulates movement of food through the bowels. Laxatives are used to treat constipation.

Rectum —The last few inches of the large intestine.

aluminum, iron supplements, tranquilizers, antispasmodics and anticonvulsants.

  • pregnancy
  • change in routine, for example traveling
  • irritable bowel syndrome
  • not drinking enough fluids; dehydration
  • laxative abuse (People become dependant on laxatives and need higher and higher doses to avoid constipation.)
  • poor bowel habits, such as ignoring the urge to have a bowel movement or refusal to use public toilets
  • tumor or other mechanical blockage
  • eating disorders such as anorexia nervosa or bulimia nervosa where there is low calorie intake and (for bulimia) vomiting
  • stroke or other conditions causing nerve damage such as multiple sclerosis, Parkinson”s disease, and spinal cord injuries
  • disorders that affect the muscles that cause material to move through the colon
  • hormonal disorders such as diabetes, hypercalcemia (too much calcium), and hypothyroidism (too little thyroid hormone)
  • abnormalities of the rectum or anus
  • iron supplements


Diagnosis begins with a medical history so that the physician can determine the normal frequency of bowel movements andthe length of time the individual has been constipated. The clinical definition of constipation requires that it be present for at least 12 weeks out of the past 12 months. The 12 weeks do not have to be consecutive.

A physical examination including a rectal exam and blood tests. Other tests, such as a thyroid hormone test, may be necessary to rule out other disorders. When symptoms are severe or do not improve with treatment, the physician may order specialized tests to determine how long material stays in the colon, evaluate the condition of the muscles of the rectum and anus, and look for evidence of cancer or other disease. These tests may include a sigmoidoscopy, barium enema x ray, colorectal transit study, and anorectal function tests.


The first choice in treating constipation is a change of diet. People with constipation are advised to eat more foods high in dietary fiber, decrease dairy, egg, and meat products to a healthy balance, and increase the amount of water and non-caffeinated beverages they drink. They are also encouraged to increase their level of physical activity and respond promptly to the urge to have a bowel movement.

When changes in diet and exercise do not work, laxatives can be used to stimulate movement of the bowels. Many types of laxatives can be purchased without a prescription. Americans spend about $725 million annually on laxatives. However, laxative dependency can become a problem with all laxatives. People who have been using laxatives regularly and wish to stop should reduce their use gradually. Each type of laxative has benefits and drawbacks. Individuals should discuss which one is best for them with their healthcare provider or pharmacist. Laxatives usually take 6–12 hours to stimulate a bowel movement.

Bulk-forming or fiber supplement laxatives are generally the safest type of laxative. Some common brand names of fiber-supplement laxatives are Meta-mucil, Citrocel, Fiberall, Konsyl, and Serutan. These must be taken with water. They provide extra fiber that absorbs water and helps keep the stool soft. The extra bulk also helps move materials through the colon.

Stool softeners help prevent the stool from drying out. They are recommended for people who should not strain to have a bowel movement, for example, people recovering from abdominal surgeries or childbirth. Brand names include Colace and Surfak.

Stimulant laxatives such as Ducolax, Senokot, Correctol, and Purge increase the rhythmic contractions of the colon and move the material along faster.

Lubricants add grease to the stool so that it moves more easily through the colon. Mineral oil is the most common lubricant.

Saline laxatives such as Milk of Magnesia draw water from the body into the colon to help soften and move the stool.

In the case of serious constipation, prescription drugs such as tegaserod (Zelnorm) may be used under the supervision of a doctor. Other medical treatment involves treating the underlying cause of the constipation such as changing a medication, removing tumors, or correcting a hormonal imbalance.

Nutrition/dietetic concerns

The major cause of constipation is poor diet. Studies find that the average American eats only 5-14 grams of fiber daily. The United States Institute of Medicine (IOM) of the National Academy of Sciences has issued the following guidelines for daily consumption of fiber.

  • men age 50 and younger: 38 grams
  • women age 50 and younger: 25 grams
  • men age 51 and older: 30 grams
  • women age 51 and older: 21 grams

There are two types of dietary fiber, and both play a role in controlling constipation. Insoluble fiber passes through the intestines undigested, adds bulk to stool, and increases the speed with which it moves through the colon. Good sources of insoluble fiber include many whole grains such as wholemeal bread, brown rice, and high bran cereals. Soluble fiber dissolves in water and forms a gel that keeps the stool soft. It also has health benefits such as lowering cholesterol (see entry for high fiber diet ). Good sources of soluble fiber include oats, apples, beans, peas, citrus fruits, barley, and carrots.

The American Dietetic Association and several other health organizations encourage people to increase the amount of fiber in their diet for many health reasons, not just to control or prevent constipation. The following list gives the fiber content of some common foods.

  • split peas, cooked, 1 cup: 16.3 g
  • lentils, cooked, 1 cup: 14.6 g
  • kidney beans, cooked, 1 cup: 13.1 g
  • brown rice, cooked, 1 cup: 3.5 g
  • 100% bran cereal, 1/2 cup: 8.4 g
  • oatmeal, 1 cup: 4.0 g
  • peas, cooked, 1/2 cup: 3.6 g
  • carrots, cooked, 1/2 cup: 2.3 g
  • potato, baked with skin: 2.5 g
  • potato, baked without skin: 1.4 g
  • apple with skin: 3.5 g
  • apple without skin: 2.7 g
  • pear with skin, 1/2: 3.1 g
  • pear without skin, 1/2: 2.5 g
  • prunes, 3: 3.0 g
  • whole-wheat bread, 1 slice: 1.9 g
  • popcorn, air popped, 2 cups: 2.4 g
  • peanuts, 10: 1.4 g


Biofeedback training may help individuals whose constipation is caused by dysfunctional control of the muscles that control the anus.


Many people have short bouts of constipation, especially when traveling, after childbirth or surgery, or with a change in lifestyle. These usually can be resolved through attention to diet and exercise. People who have chronic idiopathic constipation, irritable bowel syndrome, and the elderly (especially those who are bed or wheelchair bound), often continue to have long-term problems with constipation despite attention to diet and become dependent on laxatives. Since many people self-treat constipation with over-the-counter laxatives, rates of improvement are difficult to determine.

Some people develop hemorrhoids and cracks in their skin at the anus (anal fissures) as the result of constipation. These are painful, but not usually medically serious. Some people also develop rectal prolapse from straining to produce a bowel movement. In this case, the lining of the rectum bulges out through the anus. The most serious complication from constipation is an impaction, which is a hard mass of stool that blocks the colon. Removing an impaction often requires professional medical intervention.


A diet high in fiber, whole grains, fruits, and vegetables and low in sugar, fats, and refined grains helps promote good bowel health in most people. Adequate amounts of fluid and regular exercise also help prevent constipation from becoming a problem.



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Tish Davidson, A.M.

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