A dietary supplement widely used for achy joints does little if anything to relieve arthritic pain, according to researchers who found that chondroitin is no more effective than a placebo.
The Swiss researchers combined results from recent large-scale studies on chondroitin's effectiveness and say their results overshadow smaller, less rigorous studies that suggested a benefit.
"The longer you look and the more rigorously you look, the less effect you see," said Dr. Peter J?ni, an epidemiologist at Switzerland's University of Bern and an author of the new study.
The study, released yesterday, appears in the Annals of Internal Medicine. Its conclusion was supported by experts in the field, including Dr. Clifton Bingham, a Johns Hopkins rheumatologist.
He described chondroitin's performance as "underwhelming" in carefully designed tests. Bingham, an assistant professor of medicine at Hopkins, previously was in New York, where he was among the investigators in a multi-site study of chondroitin reviewed in the latest analysis.
Weight loss and exercise are proven to help people who suffer from osteoarthritis, he said yesterday.
However, many prefer taking a pill that appears to help them because they believe it will. "The fact is there is a very large placebo effect in the treatment of osteoarthritis," he said, adding that chondroitin has been shown to be safe.
The study suggests that there is no point in starting patients on chondroitin, but an accompanying editorial suggested that patients who say they benefit can continue taking it.
Millions swear by chondroitin, which is a component of joint cartilage. Sales of the supplement generate about $1 billion annually in the United States. It is popular among women, who are at greater risk for osteoarthritis, a condition in which cartilage deteriorates with age.
Proponents say the supplement helps repair cartilage, thus cushioning the space between bones and reducing joint pain. It is typically sold as chondroitin sulfate in a pill that also contains glucosamine, a metabolic precursor to chondroitin. They contend the Swiss study has limited relevance because it doesn't address the efficacy of the pills containing both compounds.
"Chondroitin is rarely used in this country by itself," said Mark David, a nutritional biochemist and spokesman for Pharmavite, a California-based company that sells a combination chondroitin-glucosamine supplement under the Nature Made brand. "It looks as if the combination does better than either of them alone."
However, a 2005 NIH study on combination supplements found they were ineffective.
The Swiss researchers analyzed the results of 20 studies going back to 1970 and involving more than 3,800 patients. They found that the methodology varied and the less rigorous studies tended to show positive effects.
A 2000 survey of chondroitin studies found the compound provides relief but the authors question the studies' quality. To address that, the latest review focused on three recent large-scale trials that were considered the most medically sound.