This is not the first time that research has cast doubt on the effectiveness of these two supplements. The heavily anticipated, government-funded Glucosamine/chondroitin Arthritis Intervention Trial (GAIT) also showed that overall they did not improve knee OA pain. A follow-up arm of this study showed that they did not do any better than placebo in slowing loss of cartilage that occurs in osteoarthritis of the knee. OA is the wear-and-tear form of arthritis, and affects more than 20 million people.
A smaller subset of GAIT participants with moderate-to-severe OA pain, however, did get some relief with the combined supplements. Because this group was small, researchers said the findings were preliminary and needed to be confirmed in further studies.
The new analysis of 10 studies, comprising 3,803 people, reinforces the negative findings of the GAIT trial. Glucosamine, chondroitin, or their combination are no better than placebo (dummy pill) when it comes to joint pain and joint space narrowing, the new study shows.
But the supplements are safe, the study researchers write.
The findings appear online in BMJ.
"We see no harm in having patients continue these preparations as long as they perceive a benefit and cover the cost of treatment themselves," write the researchers, who were led by Peter Jüni of University of Bern in Switzerland.
"The jury is in, and we have given these supplements a fair try," says David Pisetsky, MD, chief of rheumatology at Duke University Medical Center in Durham, N.C. "I don’t think there is a strong impetus for more study."
Pisetsky does have a number of patients who take, and will likely continue to take, these supplements.
"If you want to take them and perceive a benefit, that's fine, but tell your doctor," he says.
Jason Theodosakis, MD, an assistant clinical professor at the University of Arizona College of Medicine in Tucson, and the author of several books on the supplements, is unwavering in his support of their use in OA. He points out that there have been many positive studies, and there have been some major flaws with the design of the negative studies -- including the new analysis.
"The safety of these supplements has never been doubted," he says in an email. "You have to ask yourself, would you take a supplement containing glucosamine and chondroitin, have about two-thirds of a chance of getting significant relief, with some evidence that you can slow your disease progression, or just numb your symptoms with acetaminophen or anti-inflammatory drugs and risk ulcers, allergies, kidney or liver damage, hypertension, heart attacks and possibly death." These are some risks that have been associated with prescription and over-the-counter painkillers.
"The risk/benefit for glucosamine and chondroitin far outweighs that of the FDA-approved drugs for osteoarthritis," he says.
Many Still Stand by Supplements
Marc C. Hochberg, MD, MPH, professor of medicine and head of the division of rheumatology and clinical immunology at the University of Maryland School of Medicine in Baltimore, points out that the statistical techniques used in the new study were really not designed to be applied to groups, which may cast some doubt on the way the findings are being interpreted.
"These supplements did have a very small effect," he says. "This effect was very similar or identical to what is seen with acetaminophen, which is the first line treatment of OA according to the American College of Rheumatology and other professional organizations."
His advice? "If patients want to use glucosamine, then they should discuss this with their physician who may recommend a particular brand and manufacturer."
AndrewShao, PhD, senior vice president of scientific and regulatory affairs at the Council for Responsible Nutrition, a trade group representing supplement manufacturers, points out that the majority of published studies involving glucosamine and/or chondroitin are positive.
"We also must recognize that consumers have voted with their wallets -- choosing to continue to derive benefits from glucosamine and chondroitin supplements, with the category experiencing significant year over year growth over the past decade," he says in an email. "If these were ineffective, then we would not observe this kind of growth."
Finally, he says, the safety of these supplements is well recognized.