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Knee Arthritis: Supplements May Not Help
Sept. 30, 2008 - Results are in from a national study examining whether two popular supplements slow the progression of knee arthritis, but they are far from conclusive.
The supplements glucosamine and chondroitin sulfate, taken together or alone, failed to show a clear advantage over placebo as a treatment to slow the progression of osteoarthritis of the knee.
There was a suggestion that taking glucosamine alone might be beneficial, lead researcher Allen D. Sawitzke, MD, of the University of Utah School of Medicine, tells WebMD. But the two-year study was not large enough or long enough to show this.
"I would definitely not want the message from this study to be that these supplements don't work at all," he says. "That would be a disservice because they might prove valuable in future studies."
Glucosamine, Chondroitin Used by Millions
The latest findings are an extension of the National Institutes of Health-funded Glucosamine/chondroitin Arthritis Intervention Trial (GAIT).
In 2006, GAIT researchers reported that the supplements were not much better than placebo for reducing knee pain associated with osteoarthritis. Researchers followed close to 1,600 patients who took one or both of the supplements, the painkiller Celebrex, or placebo for six months.
Some benefit was seen in patients with moderate to severe pain who took both glucosamine and chondroitin, but the finding was not conclusive because only a small number of patients in the study had pain that was considered moderate to severe.
In an effort to determine if the supplements help slow the destruction of knee cartilage, 572 of the original GAIT participants continued to take their original study treatment for an additional 18 months. All these patients had moderate to severe osteoarthritis.
The researchers used a specific X-ray protocol to determine the rate of osteoarthritis progression over time.
After two years, there was no significant difference between treatment and placebo groups.
"While we found a trend toward improvement among those with milder osteoarthritis of the knee in those taking glucosamine alone, we were not able to draw any definite conclusions," Sawitzke says.
Interpretation of the results was also complicated by the fact that the placebo group had less arthritis progression during the two-year study than the researchers had predicted.
The X-ray protocol used to measure osteoarthritis progression also proved to be less than optimal, says Josephine Briggs, MD, who directs the NIH's National Center for Complementary and Alternative Medicine, which co-sponsored the study.
Briggs tells WebMD that better ways of measuring osteoarthritis progression may be on the horizon, including the use of MRI.
"To really understand the promise of these interventions our measures must be maximally sensitive," she says.
The latest GAIT findings appear in the October issue of the journal Arthritis & Rheumatism.
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