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A Negative Verdict for Glucosamine and Chondroitin Supplements

In 2006, the National Institutes of Health’s Glucosamine/Chondroitin Arthritis Intervention Trial (GAIT) showed that these popular arthritis supplements don’t help. But many patients held out hope that an ongoing second GAIT would uncover some benefit.

Now results are in for the second part of this landmark trial, and the final analysis suggests more of the same: Glucosamine and chondroitin supplements do not effectively treat osteoarthritis.

Cartilage cushions and protects joints. As osteoarthritis progresses, this cushion wears away, causing joint pain and disability. Glucosamine/chondroitin supplements (they are sold both as a combination pill and separately) contain compounds found in cartilage and are touted to help repair and slow joint deterioration. But it’s unknown how the body processes these compounds or if they ever make it to the cartilage.

The first GAIT analysis included 1,600 participants and measured how well glucosamine/chondroitin supplements reduced pain compared with a placebo and the proven pain reliever celecoxib (Celebrex). After six months researchers reported that, overall, these supplements were no more effective than placebo at relieving pain. As was expected, people taking celecoxib reported the greatest improvement.

Among a small group of participants with moderate to severe knee pain, those taking the combination supplement reported greater pain relief than people taking placebo, but this group was too small for researchers to say for sure that the combo works. Moreover, within this small group, placebo users reported as much pain relief as those taking celecoxib, which casts further doubt on the purported benefits of supplements.

Researchers hoped that the second GAIT analysis, which used x-rays to measure the physical effects of these supplements on knee joints, would clarify matters. Knee images from 357 people with osteoarthritis were analyzed to see if daily glucosamine/chondroitin supplements prevented a loss of joint space — the distance between the ends of bones in the joint. (Bones get closer together as cartilage wears away.) There were no meaningful differences among people taking glucosamine/chondroitin, celecoxib, or placebo.

Glucosamine and chondroitin together did worse than when each was taken alone, but again, these differences were insignificant and no better than placebo. As in the first trial, a small subgroup of patients showed a trend toward improvement. This time, however, the trend was seen in patients with less severe osteoarthritis pain who were taking glucosamine alone — not a combination supplement.

Many people will probably continue to take these supplements despite the new data — osteoarthritis hurts, relief is hard to find, and the small group of participants who benefited is still a nagging issue. About 1,500 mg a day of glucosamine alone is the most promising dosage.

But be aware that well-designed trials done independent of supplement manufacturers have not been able to prove these supplements work, despite their enormous popularity. Moreover, pills can cost more than $30 a month; this is a lot of money to spend on what might be a placebo effect.