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Glucosamine

Glucosamine

Description

Glucosamine is an amino sugar that occurs naturally in the body. This one-molecule substance consists of glucose and a hydrogen and nitrogen amine. Amino sugars are different from other body sugars, as they form part of carbohydrates. Their function is also different as they are not a source of energy, but rather are included in body tissue structure. Therefore, glucosamine plays a role in forming and maintaining the body's tissuesfor example, constructing nails, skin, eyes, bones, ligaments, tendons, heart valves, discharging mucus from the respiratory system, digestive system, and urinary tract. Glucosamine helps blend sulfur into the cartilage. When people grow older, their bodies may lose the capacity to make enough glucosamine, so the cartilage in such weight-bearing joints as the hips, knees, and hands is destroyed. The remaining cartilage then hardens and forms bone spurs , causing pain , deformed joints, and limited joint movement.

Glucosamine is not readily available from any primary food source. Commercial preparations of glucosamine are derived from chitin, which is a substance found in the outer covering of such shellfish as lobster, crab, and shrimp, as well as in such animal connective tissues as the marrow of chicken bones. Commercially prepared glucosamine comes in three formats: glucosamine sulfate, glucosamine hydrochloride, and N-acetyl-glucosamine (NAG).

General use

Glucosamine works to stimulate joint function and repair. It is most effective in treating osteoarthritis (OA), the most prevalent type of arthritis. A number of studies over the last 20 years have shown that glucosamine is helpful in relieving arthritis symptoms. For example, a 1982 clinical study compared usage of the NSAID ibuprofen with glucosamine sulfate, for osteoarthritis of the knee. During the first two weeks, ibuprofen decreased pain faster, but by the fourth week the glucosamine group was well ahead in pain relief. The overall results showed 44% of the glucosamine group had pain relief compared to 15% for ibuprofen. A British study published in 2002 reported similar findings regarding the effectiveness of glucosamine in relieving pain associated with arthritis. A team of Japanese researchers has suggested that glucosamine relieves the pain of arthritis by suppressing the functions of neutrophils, which are white blood cells that contribute to the joint inflammation found in arthritis. Other researchers think that the sulfur content of glucosamine contributes to its healing properties.

Several studies have concluded that over-the-counter preparations of glucosamine sulfate are safe for long-term treatment of osteoarthritis. These are readily available in the dietary supplement sections of most pharmacies. Glucosamine preparations are sometimes classified as nutraceuticals, a term used to refer to foods or food ingredients that are thought to provide medical or health benefits.

Harvard Medical School recently conducted a somewhat unorthodox study in which patients scheduled for hip surgery were given ground chicken bone supplements. After two weeks of taking these supplements, their pain was reduced considerably.

Glucosamine supplements can also aid in treating sports injuries, bursitis , food and respiratory allergies, asthma, osteoporosis, tendinitis, vaginitis , some skin problems, and candidiasis.

As of 2002, however, updated guidelines issued by the American College of Rheumatology for the treatment of osteoarthritis continued to list glucosamine along with acupuncture and electromagnetic therapy as treatments that are still under investigation for treating OA.

Preparations

Although commercially prepared glucosamine comes in three formats: glucosamine sulfate, glucosamine hydrochloride, and N-acetyl-glucosamine (NAG), not all three work the same. There are also differing opinions on which is better.

One claim states that glucosamine hydrochloride works 50% better than glucosamine sulfate because hydrocholoride is the main stomach acid helping the digestive system to put more active ingredients into the body. Another prefers glucosamine sulfate because of its high absorption rate of 98% documented in human studies and its sulfur content. Studies as far back as the 1930s show that people with arthritis usually have low levels of sulfur.

N-acetyl-glucosamine (NAG) can be beneficial to individuals with Crohn's disease or ulcerative colitis. Individuals with these diseases cannot change glucosamine to NAG as fast as those without the diseases. In one study, cells from patients' intestines were soaked in a solution with a 10:1 ratio of radioactive NAG to glucosamine. These cells consolidated more NAG than did the cells from the intestines of patients without Crohn's disease or ulcerative colitis.

Glucosamine is also sold mixed in formulas with devil's claw , pregnenolone, methylsulfonylmethane (MSM ), and chondroitin sulfate. Chondroitin sulfate is one of the main glycosaminoglycans (GAGs) that is contained in shark cartilage and sea cucumber. Although studies show that chondroitin sulfate has benefits, it is hard to absorb because it contains large molecules.

Further confusion can arise because glucosamine is classified and sold as a dietary supplement, meaning it has not gone through the FDA approval process. As with any dietary supplement, patients with arthritis who are considering glucosamine formulations should consult their healthcare practitioner.

The standard dosage is 500 mg three times daily. Obese people may need to take higher dosages based on their weight.

Precautions

Persons on potassium-reduced diets , with heart disease , renal diseases, or high blood pressure related to salt intake should avoid either the regular or salt-free glucosamine supplements.

Diabetics should be aware that glucosamine contains the sugar glucose, and can raise blood sugar and insulin levels. A 2000 study of 15 nondiabetic patients at the Los Angeles College of Chiropractic and MetaResponse Science showed that those who took 1,500 mg of glucosamine a day for 12 weeks had raised insulin levels. The conclusion was that the insulin rise would probably be more in diabetics. However, researchers cautioned diabetics there is no need to discard their glucosamine supplements as more controlled studies are required.

Despite the concern regarding the use of glucosamine sulfate in persons with allergies to the sulfa drugs or the sulfite additives in food, sulfur itself is a necessary mineral and human blood contains large amounts of sulfur's sulfate form. Studies show that glucosamine sulfate is safe for long term use to treat osteoarthritis, with the exception of medical conditions listed above and below.

Side effects

High dosages of glucosamine may cause gastric problems, nausea, diarrhea, indigestion , and heart-burn . Glucosamine should be taken with meals to help avoid these problems

Interactions

Glucosamine should not be taken with heart medications or insulin. Those taking diuretics may require higher amounts of glucosamine on a daily basis.

Resources

BOOKS

Ali, Elvis, et al. The All-In-One Guide to Natural Remedies and Supplements. Niagara Falls: AGES Publications, 2000.

Balch, James F., M.D. and Phyllis A. Balch, C.N.C. Prescription for Nutritional Healing. 2nd ed. New York: Penguin Putnam, 1997.

Murray, Michael, N.D. Encyclopedia of Nutritional Supplements. Roseville, CA: Prima Publishing, 1996.

Rothenberg, Mikel, M.D. and Charles Chapman. Dictionary of Medical Terms. 3rd ed. Hauppauge, NY: Barron's Educational Series, 1994.

PERIODICALS

Hua, J., K. Sakamoto, and I. Nagaoka. "Inhibitory Actions of Glucosamine, a Therapeutic Agent for Osteoarthritis, on the Functions of Neutrophils." Journal of Leukocyte Biology 71 (April 2002): 632-640.

"Joint Remedies." Consumer Reports 67 (January 2002): 18-21.

Parcell, S. "Sulfur in Human Nutrition and Applications in Medicine." Alternative Medicine Review 7 (February 2002): 22-44.

Phoon, S., and N. Manolios. "Glucosamine. A Nutraceutical in Osteoarthritis." Australian Family Physician 31 (June 2002): 539-541.

Ruane, R., and P. Griffiths. "Glucosamine Therapy Compared to Ibuprofen for Joint Pain." British Journal of Community Nursing 7 (March 2002): 148-152.

Schnitzer, T. J., and the American College of Rheumatology. "Update of ACR Guidelines for Osteoarthritis: Role of the Coxibs." Journal of Pain and Symptom Management 23 (April 2002)(Supplement 4): S24-S30.

ORGANIZATIONS

American College of Rheumatology. 1800 Century Place, Suite 250, Atlanta, GA 30345. (404)633-3777. <www.rheumatology.org>.

OTHER

"Glucosamine: Is it a beneficial arthritis treatment?" <http://www.onhealth.com>.

Sharon Crawford

Rebecca J. Frey, PhD

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glucosamine

glucosamine The amino derivative of glucose, a constituent of a variety of complex polysaccharides. A component of cartilage in joints, and glucosamine sulphate has been used in treatment of osteoarthritis with some evidence of efficacy.

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glucosamine

glucosamine See amino sugar.

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Glucosamine

Glucosamine

Definition

Purpose

Description

Precautions

Interactions

Complications

Parental concerns

Resources

Definition

Glucosamine is a natural compound found in the human body, specifically an amino monosaccharide (a nitrogen-containing sugar). It is thought to possibly play a role in cartilage formation and repair and to perhaps have an anti-inflammatory affect within humans.

Glucosamine is also known as 2-amino-2-deoxy-glucose; 2-amino-2-deoxy-beta-D-glucopyranose; and chitosamine. The chemical symbol for glucosamine is C6H13NO5. It is sold as a nutritional or dietary supplement in three forms: glucosamine hydrochlo-ride (glucosamine HCl), glucosamine sulfate, and N-acetyl-glucosamine (NAG). Within scientific studies, there appears to be no difference between the three forms with regards to their effectiveness.

Glucosamine is found is various forms when it is sold commercially. Some of these forms include capsules (500 milligrams [mg], 550 mg, 750 mg, and 1,000 mg), liquid (500 mg per five milliliters), tablets (340 mg, 500 mg, and 1,000 mg), and powder.

Purpose

When taken as anoral supplement, glucosamine is sometimes used in the treatment of a type of arthritis called osteoarthritis. Osteoarthritis is considered the largest and most widely occurring type of arthritis. Osteoarthritis, also called degenerative joint disease, is caused by deterioration or loss of cartilage at one or more joints of the body. The symptoms range from mild pain and stiffness to complete loss of use of the joint, and may or may not have an identifiable cause. Unlike the less common rheumatoid arthritis, osteoarthritis is not marked by inflammation. While osteoarthritis is commonly associated with overweight, cartilage deterioration can be caused by excessive wear and tear on the joints, which may be due to excessive physical exercise or exertion. People aged 60 years or older often have osteoarthritis. According to the U.S. Centers for Disease Control and Prevention (CDC), over 21 million people in the United States annually suffer with osteoarthritis.

The use of glucosamine in osteoarthritis therapy seems to be considered generally safe among medical professionals. However, it is not completely accepted within the medical community as being effective for osteoarthritis treatment. In the United States, the Food and Drug Administration (FDA) has not approved the use of glucosamine for medical use within humans. It is classified as a dietary supplement

so FDA approval is not needed as long as companies do not advertise it as a treatment for a medical condition. Instead, in the United States, glucosamine is a widely popular alternative medicine for the relief of joint pain. In Europe, however, the glucosamine-form glucosamine sulfate is approved as a medical drug.

Besides osteoarthritis, glucosamine is also used to relieve symptoms of leg pain, rheumatoid arthritis, inflammatory bowel disease (such as ulcerative colitis and Crohn’s disease), and temporomandibular joint (TMJ) disorders. Scientific results show some positive evidence for the effective use of glucosamine with osteoarthritis; however, the scientific evidence is much more unclear for the other diseases.

Description

Glucosamine is taken from animal tissue, specifically from the shells of crabs, lobsters, and shrimp. Within these shellfish, glucosamine is made naturally in the form of glucosamine-6-phosphate, which eventually makes glycosaminoglycans, among other substances. Since glucosamine-6-phosphate helps to regulate the production of joint cartilage and glycosaminoglycans are a major component of cartilage, glucosamine may help to rebuild cartilage and treat arthritis. Whether these glu-cosamine processes could be involved in human arthritis remains undecided in the medical community. Not all medical professional believe glucosamine is effective

.

KEY TERMS

Antihistamine— Drugs that treat allergies.

Autism— Condition that causes disturbances in psychological development within children such as problems in relationships; perceiving, interpreting, and reacting to stimuli, and using language.

Diabetes— Medical problem that affects blood sugar levels and causes the body to produce urine in excessive amounts.

Fetus— Unborn offspring.

Gastrointestinal— Relating to the stomach and intestines.

Sedative— Medicines that increase drowsiness and calmness.

Tranquilizer— Medicines that reduce anxiety and tension.

A typical dosage of glucosamine is 1,500 milligrams per day. The two most commonly sold forms are glucosamine sulfate and glucosamine hydrochlor-ide. Glucosamine is often sold in combination with other supplements such as chondroitin sulfate(a sul-fated glycosaminoglycan composed of a chain of alternating sugars) and methylsulfonylmethane (MSM, an organic sulfur compound within the chemical class of sulfones).

When glucosamine is taken orally into the body (as a pill), according to conclusions from scientifically based animal studies, it is absorbed into the small intestine. It then travels into the liver where most of it is metabolized. Based on these studies, some of it does apparently go to cartilage; however, it is not known how much is actually transmitted to joints. It is primarily removed from the body through urine.

Precautions

Clinical studies have consistently showed that glucosamine is safe when used as directed. However, according to the National Institutes of Health (NIH), side effects may include drowsiness, headache, upset stomach, insomnia, skin reactions, light sensitivity, and nail toughening. Rare symptoms include abdominal pain, appetite loss, vomiting, nausea, intestinal gas, heartburn, and diarrhea.

The National Institutes of Health recently sponsored a large, multi-institutional clinical trial to test the effects of chondroitin sulfate, glucosamine, and the combination of the two on knee osteoarthritis. (Chondroitin is a carbohydrate that is a component of cartilage. It is thought to help promote water retention and elasticity in cartilage and help prevent enzymes from destroying cartilage.) The study is the largest of its kind to date with respect to research into the two substances.

The four-year study, known as Glucosamine/ chondroitin Arthritis Intervention Trial (GAIT), involved almost 1,600 participants and 16 research facilities. It was funded by the National Center for Complementary and Alternative Medicine and the National Institute of Arthritis and Musculoskeletal and Skin Diseases. The lead researcher in the study was Daniel O. Clegg from the University of Utah, School of Medicine (Salt Lake City). Five different treatments were given daily for 24 weeks: glucosamine alone (1,500 mg), chondroitin sulfate alone (1,200 mg), glucosamine and chondroitin sulfate combined (same doses), a placebo, or celecoxib (200 mg) (a FDA-approved drug for osteoarthritis pain, and branded in the United States as Celebrex®).

According to the resulting 2006 article “Glucosamine, chondroitin sulfate, and the two in combination for painful knee osteoarthritis” in the New England Journal of Medicine,the six-month trial found that patients taking glucosamine, chondroitin sulfate, or a combination of the two had no significant decrease in their major osteoarthritis symptoms compared to patients taking a placebo. Patients who took celecoxib had a significant decrease in the severity of their symptoms. However, glucosamine and chondroitin sulfate together seemed to help people with pain classified as moderate-to-severe. With people in the mild pain group, glucosamine and chondroitin sulfate together or alone did not provide substantial relief.

Interactions

For the most part, glucosamine does not show any contraindications with other drugs; that is, medical studies have not shown that it is harmful to users. Scientific studies have shown that the use of glucosamine (as directed) does not produce any serious, permanent problems.

Glucosamine is derived from the shells of shellfish. People with shellfish allergies or iodine hypersensitivity may not want to take it. It is important to note that people with shellfish allergies are usually allergic to the skin (protein) of shellfish, and not to the actual shells (chitin). According to a 2004 article from the Journal of Allergy and Clinical Immunology, most people with shellfish allergies can safely take glucosamine. However, it is always wise to ask a physician before taking any new medicines. According to the NIH, throat swelling may occur if glucosamine reacts negatively in people with shellfish allergies.

Glucosamine taken above the recommended dosages could decrease the effectiveness of insulin or other such drugs that control blood sugar levels in diabetes. According to the NIH, some studies show a connection while other studies do not; however, the connection has been suggested as possible by the medical community.

Reports from the NIH suggest that glucosamine may also increase the risk of bleeding especially when taking aspirin, blood thinners, anti-platelet drugs, and non-steroidal anti-inflammatory drugs. The use of glucosamine has also been possibly linked to the increase in the frequency and severity of asthma.

Since glucosamine is not approved by the FDA, its safety and formulation is determined solely by the manufacturer. Thus, quality and content may vary among manufacturers. Tests have been performed by ConsumerLab.com, a leading provider of independent tests for nutritional and health products and services. Technicians at the laboratory report that the majority of companies manufacturing glucosamine for consumer use provide at least 90% of the amount of glucosamine stated on the label.

The Arthritis Foundation recommends that, if using glucosamine, consumers should buy from established companies (because they can more easily be held accountable for their products); read the product label carefully (if need be, ask the pharmacist questions); consult with the family doctor before trying new medicines; verify the source of the medical problem before beginning glucosamine; make sure the physician is aware of any future plans to take glucosamine; and do not reduce or eliminate prescription medicines one is already taking.

If deciding to take glucosamine, try it between six to eight weeks. It generally takes this amount of time before any noticeable effects are felt. Sometimes, no effects are felt. If a reduction of symptoms is not noticed at the end of this period of time, the Arthritis Foundation states that glucosamine will probably not help.

Complications

The use of alcohol, tranquilizers, sedatives, anti-seizure drugs, anti-anxiety drugs, muscle relaxants, and antihistamine medicines may intensify the drowsiness side effect that is possible with glucosamine. Thus, if taking glucosamine and any of these drugs together, users should be aware (and warned) that it may adversely affect one’s concentration. Consumers should talk with a medical professional before taking glucosamine.

People who are overweight, have diabetes, or liver disease should check their blood sugar levels more frequently when taking glucosamine because it is an amino sugar. If taking blood-thinning medication or daily aspirin therapy, blood clotting time should be tested more frequently.

A person can overdose on glucosamine. The amount of glucosamine varies with the supplemental form. Pure glucosamine hydrochloride is at a concentration of about 83% in the glucosamine base; pure glucosamine sulfate is approximately 65%, and pure N-acetyl glucosamine is around 75%.

Parental concerns

According to the NIH, there is no scientific evidence to show that glucosamine should be given to children. Methylsulfonylmethane (MSM), which is sometimes packaged with glucosamine, has been shown to have a relationship with autism, but whether that association is good or bad is not currently known.

Osteoarthritis does affect children. Clinical studies have not proven whether or not glocosamine— either in children or adults—should be recommended as a medical therapy for osteoarthritis. Some studies show that glucosamine can help people with mild to moderate osteoarthritis and prevent the deterioration of cartilage. However, other studies do not show these benefits. The majority of studies have been performed with glucosamine hydrochloride and glucosamine sul-fate; but not with N-acetyl-glucosamine.

In any case, the effects of these glucosamine supplements on a growing child or developing baby are not yet known. For that reason, glucosamine is not recommended for, and should not be taken by, children. Because of the lack of long-term effects on a developing fetus and child, women who are pregnant and women who could become pregnant are advised by the Arthritis Foundation not to take glucosamine.

Resources

BOOKS

Bartlett, Susan J. Clinical Care in the Rheumatic Diseases. Atlanta, GA: Association of Rheumatology Health Professionals, 2006.

Imboden, John B, David B. Hellmann, and John H. Stone, eds. Current Rheumatology Diagnosis and Treatment. New York: Lange Medical Books/McGraw-Hill, 2004.

PERIODICALS

Bruyere, O, K. Pavelka, L.C. Rovati, et al. “Glucosamine sulfate reduces osteoarthritis progression in postmenopausal women with knee osteoarthritis: evidence from two 3-year studies” Menopause. 11(2): 138–143, 2004.

Clegg, D.O, et al. “Glucosamine, chondroitin sulfate, and the two in combination for painful knee osteoarthritis” New England Journal of Medicine. 354: 795–808, 2006.

Gray, H., P. Hutcheson, and R. Slavin. “Is glucosamine safe in patients with seafood allergy?” Journal of Allergy and Clinical Immunology. 114:459–460, 2004.

Hochberg, M.C. “Nutritional supplements for knee osteoarthritis—Still no resolution” New England Journal of Medicine. 354:848–850, 2006.

OTHER

Efficacy of Glucosamine and Chondroitin Sulfate May Depend on Level of Osteoarthritis Pain. HIH News, National Institutes of Health. February 22, 2006 [Cited March 18, 2007]. <http://www.nih.gov/news/pr/feb2006/nccam-22.htm>.

ORGANIZATIONS

ConsumerLab.com. Home page of ConsumerLab.com. [Cited March 18, 2007] <http://www.consumerlab.com/>.

William Arthur Atkins.

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Glucosamine

Glucosamine

Description

Glucosamine is an amino sugar that occurs naturally in the body. This one-molecule substance consists of glucose and a hydrogen and nitrogen amine. Amino sugars are different from other body sugars, as they form part of carbohydrates . Their function is also different as they are not a source of energy, but rather are included in body tissue structure. Therefore, glucosamine plays a role in forming and maintaining the body's tissues, for example, constructing nails, skin, eyes, bones, ligaments, tendons, heart valves; and discharging mucus from the respiratory system, digestive system, and urinary tract. Glucosamine helps blend sulfur into the cartilage. When people grow older, their bodies may lose the capacity to make enough glucosamine, so the cartilage in such weight-bearing joints as the hips, knees, and hands is destroyed. The remaining cartilage then hardens and forms bone spurs, causing pain , deformed joints, and limited joint movement.

Glucosamine is not readily available from any primary food source. Commercial preparations of glucosamine are derived from chitin, which is a substance found in the outer covering of such shellfish as lobster, crab, and shrimp, as well as in such animal connective tissues as the marrow of chicken bones. Commercially prepared glucosamine comes in three formats: glucosamine sulfate, glucosamine hydrochloride, and N-acetyl-glucosamine (NAG).

General use

Glucosamine works to stimulate joint function and repair. It is most effective in treating osteoarthritis (OA) , the most prevalent type of arthritis. A number of studies between 1980 and the early 2000s showed that glucosamine is helpful in relieving arthritis symptoms. For example, a 1982 clinical study compared usage of the NSAID ibuprofen with glucosamine sulfate, for osteoarthritis of the knee. During the first two weeks, ibuprofen decreased pain faster, but by the fourth week the glucosamine group was well ahead in pain relief. The overall results showed 44% of the glucosamine group had pain relief compared to 15% for ibuprofen. A British study published in 2002 reported similar findings regarding the effectiveness of glucosamine in relieving pain associated with arthritis. A team of Japanese researchers suggested that glucosamine relieves the pain of arthritis by suppressing the functions of neutrophils, which are white blood cells that contribute to the joint inflammation found in arthritis. Other researchers speculated that the sulfur content of glucosamine contributes to its healing properties.

Several studies have concluded that over-the-counter preparations of glucosamine sulfate are safe for long-term treatment of osteoarthritis. These are readily available in the dietary supplement sections of most pharmacies. Glucosamine preparations are sometimes classified as nutraceuticals, a term used to refer to foods or food ingredients that are thought to provide medical or health benefits.

Harvard Medical School conducted a somewhat unorthodox study in which patients scheduled for hip surgery were given ground chicken bone supplements. After two weeks of taking these supplements, their pain was reduced considerably.

Glucosamine supplements can also aid in treating sports injuries, bursitis , food and respiratory allergies, asthma, osteoporosis , tendinitis, vaginitis, some skin problems, and candidiasis.

As of 2002 updated guidelines issued by the American College of Rheumatology for the treatment of osteoarthritis continued to list glucosamine along with acupuncture and electromagnetic therapy as treatments that were still under investigation for treating OA. Although there was considerable clinical experience with glucosamine, the mechanism of action was not determined, and analysis of published studies was inconclusive. In one study, sponsored by the National Institutes of Health (NIH), the Glucosamine/Chondroitin Arthritis Intervention Trial (GAIT), which enrolled 1,583 patients with painful knee osteoarthritis, 39 individuals failed to reveal an effect of glucosamine or chondroitin alone or in combination when compared to placebo. However, this study tested glucosamine hydrochloride, while more favorable studies have used glucosamine sulfate. Also, the favorable placebo response of 60% made analysis of the data difficult. When so many patients respond favorably to the placebo, it can be difficult to show a significant difference between the active drug and the inactive control. A review by the Arthritis Center of Boston University School of Medicine warned: “Trials of glucosamine and chondroitin preparations for (osteoarthritis) symptoms demonstrate moderate to large effects, but quality issues and likely publication bias suggest that these effects are exaggerated.”

A study from the Rheumatology Unit, Department of Clinical and Experimental Medicine of the University of Padova, Italy, offered a mechanism of action explaining the observed physiologic effects of glucosamine. In their observation, glucosamine sulfate has anti-oxidant properties and inhibits natural oxidative stress that can cause unfavorable alterations of cartilage. These observations would explain the clinical reports of glucosamine activity and differentiate it from a placebo response.

Preparations

Although commercially prepared glucosamine comes in three formats (glucosamine sulfate, glucosamine hydrochloride, and N-acetyl-glucosamine (NAG)), not all three work the same. There are also differing opinions on which is best.

One claim states that glucosamine hydrochloride works 50% better than glucosamine sulfate because hydrochloride is the main stomach acid helping the digestive system to put more active ingredients into the body. Another prefers glucosamine sulfate because of its high absorption rate of 98% documented in human studies and its sulfur content. Studies as far back as the 1930s show that people with arthritis usually have low levels of sulfur.

N-acetyl-glucosamine (NAG) can be beneficial to individuals with Crohn's disease or ulcerative colitis. Individuals with these diseases cannot change glucosamine to NAG as fast as those without the diseases. In one study, cells from patients' intestines were soaked in a solution with a 10:1 ratio of radioactive NAG to glucosamine. These cells consolidated more NAG than did the cells from the intestines of patients without Crohn's disease or ulcerative colitis.

Glucosamine is also sold mixed in formulas with devil's claw, pregnenolone, methylsulfonylmethane (MSM), and chondroitin sulfate. Chondroitin sulfate is one of the main glycosaminoglycans (GAGs) that is contained in shark cartilage and sea cucumber. Although studies show that chondroitin sulfate has benefits, it is hard to absorb because it contains large molecules.

Further confusion can arise because glucosamine is classified and sold as a dietary supplement, meaning that as of the early 2000s it had not gone through the FDA approval process. As with any dietary supplement, patients with arthritis who are considering glucosamine formulations should consult their healthcare practitioner.

KEY TERMS

Amino acids —Organic acids containing nitrogen that are the building blocks of proteins.

Carbohydrates —Organic substances, usually from plant sources. They are made up of carbon, hydrogen, and oxygen and are the diet's major source of energy.

Chitin —A transparent horny substance found in the outer coverings of shellfish. Chitin is used to make commercial preparations of glucosamine.

Glucose —Simple sugar that serves as the main energy source for cells.

NSAIDs —Nonsteroidal anti-inflammatory drugs given to suppress inflammation. Ibuprofen is a typical NSAID.

Nutraceutical —A food or food ingredient that is thought to provide medical or health benefits. Glucosamine preparations are classified as nutraceuticals.

Osteoarthritis —Degenerative joint disease that affects the hips, knees, or spine. Pain occurs after exercise and the joints can become stiff and swell. This common type of arthritis occurs in 80% of people over 50.

Placebo —A substance that has no therapeutic effect. A placebo may be prescribed for the psychological benefit of the patient, or it may be used as a control in testing new drugs.

Rheumatology —The medical specialty that studies and treats disorders of the joints and muscles.

Tendinitis —Inflammation of tissues that connect muscles to bones. Tendinitis is usually caused by strain or an injury.

The standard dosage is 500 mg three times daily. Obese people may need to take higher dosages based on their weight.

Precautions

Persons on potassium-reduced diets, with heart disease , renal diseases, or high blood pressure related to salt intake should avoid either the regular or salt-free glucosamine supplements.

Diabetics should be aware that glucosamine contains the sugar glucose and can raise blood sugar and insulin levels. A 2000 study of 15 nondiabetic patients at the Los Angeles College of Chiropractic and MetaResponse Science showed that those who took 1,500 mg of glucosamine a day for 12 weeks had raised insulin levels. The conclusion was that the insulin rise would probably be more in diabetics. Researchers cautioned diabetics that so far there was no need to discard their glucosamine supplements as more controlled studies were required.

Despite the concern regarding the use of glucosamine sulfate in persons with allergies to the sulfa drugs or the sulfite additives in food, sulfur itself is a necessary mineral and human blood contains large amounts of sulfur's sulfate form. Studies show that glucosamine sulfate is safe for long-term use to treat osteoarthritis, with the exception of the medical conditions mentioned.

Side effects

High dosages of glucosamine may cause gastric problems, nausea, diarrhea , indigestion, and heartburn . Glucosamine should be taken with meals to help avoid these problems

Interactions

Glucosamine should not be taken with heart medications or insulin. Those taking diuretics may require higher amounts of glucosamine on a daily basis.

Resources

PERIODICALS

Krasnokutsky, S., J. Samuels, and S. Abramson. “Osteoarthritis in 2007.” Bulletin of the NYU Hospital for Joint Diseases (2007): 222–8.

Clegg, D. O., D. J. Reda, C. L. Harris, et al. “Glucosamine, Chondroitin Sulfate, and the Two in Combination for Painful Knee Osteoarthritis.” New England Journal of Medicine (2006): 795–808.

Valvason, C., E. Musacchio, A. Pozzuoli, R. Ramonda, R. Aldegheri, and L. Punzi. “Influence of Glucosamine Sulphate on Oxidative Stress in Human Osteoarthritic Chondrocytes: Effects on HO-1, p22(Phox) and iNOS expression.” Rheumatology (January 2008): 31–5.

ORGANIZATIONS

American College of Rheumatology. 1800 Century Place, Suite 250, Atlanta, GA 30345-4300. (404) 633-3777. www.rheumatology.org.

OTHER

“Glucosamine Trials Show Little Benefit Against Arthritis,” 2007. http://www.medicinenet.com/script/main/art.asp?articlekey=82234 (February 8, 2008).

Sharon Crawford

Rebecca J. Frey Ph.D.

Sam Uretsky PharmD

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