Glucosamine and chondroitin sulfate for osteoarthritis of the knee - Harvard Medical School

"...overall, the supplements didn’t reduce pain any better than a placebo. Broken out by groups, the data suggested that combined glucosamine and chondroitin sulfate helped ease moderate to severe (not mild) pain; but the numbers of patients were too small to be certain..."

Until recently, glucosamine supplements (with or without chondroitin sulfate) held great promise as a treatment for the more than 20 million Americans affected by osteoarthritis, a chronic disorder characterized by the breakdown of cartilage in the joints and painful bone-on-bone friction. Both glucosamine and chondroitin sulfate are biochemicals that occur naturally in the body and are involved in the growth, repair, and maintenance of cartilage. Early research suggested that these compounds might slow cartilage deterioration and relieve osteoarthritis symptoms, including pain, stiffness, and reduced function. Since habitual use of traditional pain relievers — acetaminophen and nonsteroidal anti-inflammatory drugs (NSAIDs) — carries the risk of serious side effects, the public embraced these supplements as a safe long-term option.

Osteoarthritis of the knee Osteoarthritis is characterized by the breakdown of cartilage, a protective tissue that covers the ends of bones. In the knee, the cartilage covering the condyles (the knobs at the lower end of the thigh bone) degrades, which can result in the femur and tibia rubbing against each other.

Some studies of glucosamine and chondroitin sulfate have shown benefits, but these were small and, in some cases, sponsored by groups with a financial interest in the supplements. To settle the question, the National Institutes of Health sponsored the Glucosamine/chondroitin Arthritis Intervention Trial (GAIT), a large, randomized controlled trial of glucosamine and chondroitin sulfate supplements in people with osteoarthritis of the knee. The average age of participants was 59, and 64% were women. All had mild to moderate or severe knee pain and x-ray evidence of osteoarthritis. For six months, participants were assigned to groups that variously took glucosamine, chondroitin sulfate, glucosamine and chondroitin together, celecoxib (Celebrex), or a placebo. Symptoms were monitored every four to eight weeks.

The GAIT investigators found that, overall, the supplements didn’t reduce pain any better than a placebo. Broken out by groups, the data suggested that combined glucosamine and chondroitin sulfate helped ease moderate to severe (not mild) pain; but the numbers of patients were too small to be certain. Results were published in the New England Journal of Medicine (Feb. 23, 2006).

The GAIT researchers are now carefully analyzing the x-ray data, in part because earlier x-ray studies suggested that glucosamine and chondroitin sulfate slowed osteoarthritis progression.

Given these findings, it’s hard to be enthusiastic about glucosamine and chondroitin sulfate for osteoarthritis in the knee. We don’t know if the supplements would be more effective taken for a longer time. They’re fairly safe but can be expensive, and they’re not FDA-regulated, so ingredients and amounts may vary.

If you plan to take glucosamine and chondroitin sulfate, keep some points in mind. The supplement hasn’t been tested in elderly or pregnant women. Chondroitin sulfate is chemically similar to blood-thinning drugs such as Coumadin (warfarin), heparin, and aspirin and can cause excessive bleeding. People with diabetes should be aware that in animal studies, glucosamine increases blood sugar levels. (No such effects were found in GAIT participants, but the study wasn’t specifically designed to address that question.)

Whether or not you take glucosamine and chondroitin sulfate, there are several things you can do to reduce osteoarthritis symptoms. Resistance exercise can strengthen the muscles surrounding your painful joints, helping to support them and reduce stress on them. Aerobic conditioning will improve your endurance. Weight control is crucial to reducing both the physical load on joints and the resulting pain. If your pain is due to joint misalignment, check with your doctor to see if you would benefit from a brace or an orthotic in your shoe. Devices like canes, walkers, and raised seats relieve stress on joints. Also consider heat and ice, analgesics (NSAIDs and acetaminophen), and topical pain relievers such as capsaicin cream (made from the active ingredient in hot pepper).

— Celeste Robb-Nicholson, M.D.
Editor in Chief, Harvard Women’s Health Watch

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Emphasis (bold & italics) added by Davies