Glucosamine, which occurs naturally in the body, plays a key role in the construction of cartilage -- the tough connective tissue that cushions the joints. Glucosamine stimulates the production of glycosaminoglycans (the key structural components of cartilage) as well as the incorporation of sulfur into cartilage. Sulfur is necessary for making and repairing cartilage.

Glucosamine may be effective in treating and possibly slowing the progression of osteoarthritis. This is a type of arthritis caused by continuous wear and tear on the joints leading to inflammation, breakdown, and eventual loss of cartilage. The tissues most affected by osteoarthritis are the weight bearing joints, such as the knees and hips, as well as the joints in the hands.

Studies suggest that glucosamine may be at least as effective as some of the medications frequently used to treat this joint condition, but with fewer gastrointestinal side effects. The medications used to treat osteoarthritis are known as nonsteroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen and piroxicam. NSAIDs may cause stomach upset, cramps, constipation, diarrhea, and in some cases, stomach ulcers.

Glucosamine is often taken with chondroitin, another supplement thought to be effective in treating arthritis. These substances are often combined with manganese as well, a trace metal that is also needed for building cartilage.

Arthritis
Although not every single study agrees, strong evidence from many well-designed trials, indicate that glucosamine sulfate supplements may be an effective treatment for osteoarthritis -- particularly osteoarthritis of the knee. In general, findings from these studies suggest that glucosamine provides several benefits for people with osteoarthritis including pain reduction (as effective as ibuprofen and other NSAIDs), improved function and mobility, and slowed progression or even prevention of joint destruction when taken for 3 or more years.

In comparison to NSAIDs, glucosamine takes longer to begin working. However, pain control lasts longer with glucosamine and the supplements cause fewer side effects.

Although glucosamine and chondroitin are often administered together for the treatment of osteoarthritis, it is not clear that the combination works better than either supplement alone. Nor is it clear if glucosamine is better than chondroitin or vice versa. Perhaps the most definitive results regarding the effectiveness of glucosamine and chondroitin for osteoarthritis will be achieved with the ongoing Glucosamine/Chondroitin Arthritis Intervention Trial sponsored by the National Institutes of Health. This large-scale study involving over 1,600 people is investigating the effects of glucosamine alone, chondroitin alone, and a combination of both for the treatment of knee osteoarthritis. Results are expected in 2005.

Inflammatory Bowel Disease (IBD)
Crohn's disease and ulcerative colitis are two inflammatory bowel diseases that are marked by chronic, recurrent bloody diarrhea. Preliminary evidence suggests that N-acetyl glucosamine oral supplements or enemas may improve symptoms of IBD in children who do not improve from standard medical treatments. Further research is needed, however, to determine whether the substance is safe and effective for the treatment of IBD.

There are no food sources of glucosamine. Supplements are derived from either bovine cartilage or chitin, the hard outer shells of shrimp, lobsters, and crabs.

Glucosamine is available as an oral supplement in the following forms:

• Glucosamine sulfate: 500, 750, and 1,000 mg capsules and tablets
• N-acetyl glucosamine: 500 and 750 mg capsules and tablets
• Glucosamine hydrochloride (HCL): 500, 750, and 1,000 mg capsules and tablets
• Glucosamine/chondroitin sulfate combination products (often contain manganese as well)

Glucosamine sulfate is the form used in most research studies. It is believed to be the best source because it provides the sulfur necessary for making and repairing cartilage.

Glucosamine is also available as an injectable form that your physician can insert directly into the arthritic joint. N-acetyl glucosamine is also available as an enema.

Pediatric

There are no known scientific reports on the pediatric use of glucosamine. Therefore, it is not currently recommended for children.

Adult

• 1,500 mg per day (500 mg three times a day) for one to two months

Ongoing supplementation (roughly 1,000 mg per day) may be required to prevent the progression of osteoarthritis or to reduce pain and inflammation associated with the condition.

Because of the potential for side effects and interactions with medications, dietary supplements should be taken only under the supervision of a knowledgeable healthcare provider.

The majority of studies indicate that glucosamine is safe, nontoxic, and causes only minor side effects such as stomach upset, heartburn, indigestion, gas, bloating, and diarrhea. If these symptoms occur, glucosamine should be taken with food.

People with peptic ulcers should take glucosamine sulfate with food.

Glucosamine sulfate may contain high amounts of sodium or potassium, so individuals on a restricted diet or taking potassium-sparing diuretics should carefully check the label before taking glucosamine supplements.

People with diabetes should have their blood sugar checked regularly as glucosamine may cause insulin to work less effectively. Some glucosamine supplements are derived from shellfish, so individuals with shellfish allergies should check with a health care professional before taking these supplements.

People who are allergic to sulfur are usually allergic to sulfa drugs or sulfite-containing food additives. Sulfur is an essential nutrient that is naturally present in the body of all individuals. "Sulfur-sensitive" people can safely use glucosamine sulfate.

If you are currently being treated with any of the following medications, you should not use glucosamine or make any adjustments to your medications without first talking to your healthcare provider.

Nonsteroidal Anti-inflammatory Drugs (NSAIDs)
Glucosamine may increase the anti-inflammatory activity of NSAIDs such as ibuprofen. This interaction may result in the need for lower doses of these medications.

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