WebMD Medical News
Louise Chang, MD
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."
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
"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
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.
Roughly 21 million American have osteoarthritis. While many patients end up
having surgery to replace worn-out knees, Sawitzke says there are few
nonsurgical treatments that address disease progression.
"Right now we essentially have nothing to offer," he says.
He recommends that people who want to try one of the supplements use
glucosamine alone rather than glucosamine and chondroitin because there is some
evidence that glucosamine absorption is compromised with the combination
"I tell my patients who want to take it for pain to try it for a few
weeks or a month," he says. "That should be long enough to tell if it
is working for you."
The GAIT study and others suggest that glucosamine and chondroitin are safe
supplements, but Briggs says patients who take them or any supplement should
always discuss it with their doctor.
She says more than two out of three adults in the U.S. use some type of
complementary or alternative medicine, but only about one in three tell their
physicians about it.
"It is important to discuss any medication you take with your
doctor, including complementary and alternative medicines," she says.
SOURCES:Sawitzke, A.D., Arthritis & Rheumatism, October 2008; vol 58: pp
3183-3191.Allen D. Sawitzke, MD, University of Utah School of Medicine, Salt Lake
City.Josephine P. Briggs, MD, director, National Center for Complementary and
Alternative Medicine, National Institutes of Health, Bethesda, Md.
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