A popular dietary supplement appears to slow the progression of knee osteoarthritis (OA) and is as effective at controlling pain as a widely used prescription medication, according to a study presented at the 2015 American College of Rheumatology Annual Meeting. A team of Canadian researchers found that, over a span of two years, patients with knee OA who took chondroitin sulfate, which is sold over the counter (OTC), lost less knee cartilage than a second group of patients treated with the prescription nonsteroidal anti-inflammatory drug (NSAID) celecoxib (Celebrex). This new study fuels an ongoing debate over whether OA patients can benefit from OTC supplements such as chondroitin.
Chondroitin is a naturally occurring molecule your body uses to build healthy cartilage, the shock-absorbing tissue that protects the ends of bones where they form joints. (Gradual loss of cartilage leads to the pain, stiffness and other symptoms of OA.) Chondroitin supplements are made from cartilage taken from animals, such as sharks and cows, though they also can be produced synthetically. In theory, the supplements help restore lost cartilage, though some evidence suggests that they reduce inflammation, too. Chondroitin is often sold in combination with another dietary supplement marketed for joint health, glucosamine.
The study presented at the ACR conference was led by Jean-Pierre Pelletier, MD, a professor of medicine at the University of Montreal and director of OA research at the University of Montreal Hospital Research Centre. Dr. Pelletier and his colleagues recruited 194 men and women with moderately severe knee osteoarthritis to participate. At the outset, the researchers performed quantitative magnetic resonance imaging (qMRI) on all study participants to measure how much cartilage remained in their knees. (qMRI is an advanced technique that reveals information about the biochemical structure of tissue that can’t be obtained with a traditional MRI.) They also wanted a snapshot of other factors that play a role in OA, such as the presence of bone marrow lesions (which can increase pain levels) and thickening of soft tissue in the joint known as the synovial membrane (which can cause stiffness). In addition, doctors examined each patients’ knees for swelling, and study subjects filled out forms to rate their pain and other symptoms
Next, participants were split into two groups. Half were asked to take a daily dose of chondroitin (1,200 milligrams), while the rest of the study subjects were given celecoxib (200 milligrams). Previous research has shown that while celecoxib helps with the pain and swelling of OA, it does not affect the underlying damage in the knee or the disease process.
Two years later, Dr. Pelletier’s group performed a fresh set of qMRIs, which indicated that patients who took chondroitin had lost less knee cartilage than their counterparts treated with celecoxib. In particular, the chondroitin users retained 20%more cartilage in the inner portion of the knee, known as the medial compartment. Earlier studies suggest that could be sufficient cartilage retention for a patient to avoid total knee replacement surgery, said Dr. Pelletier via email.
Chondroitin and celecoxib users in this study enjoyed a similar improvement in swelling and other symptoms; pain in each group was reduced by roughly 50%. Overall, patients tolerated both therapies well. However, celecoxib and other NSAIDs are associated with an increased risk for cardiovascular disease, which is not true of chondroitin. The latter, says Dr. Pelletier, “could, indeed, represent a safer alternative to NSAIDs with a similar level of efficacy on disease symptoms.”
Some, though not all, previous research has suggested that chondroitin might be worth trying if you have knee OA. Earlier this year, the Cochrane Collaboration – an independent organization that evaluates medical therapies – analyzed 43 studies including more than 9,000 patients (most of whom had knee OA), and determined that chondroitin may offer a “small to moderate” reduction in pain and slight slow-down in loss of cartilage. However, authors of the Cochrane review noted that many of the studies had flaws in their design or execution.
Despite Dr. Pelletier’s optimistic results, many doctors remain skeptical about the potential benefits of chondroitin. “It seems relatively safe, and if it works, that would be great. But I’d like to see more evidence,” says Cleveland Clinic rheumatologist Howard Smith, MD, who adds that the quality of OTC dietary supplements is not closely regulated in the United States by the Food and Drug Administration. “The risk-benefit ratio may favor trying chondroitin,” says Dr. Smith, “but who knows what’s in the bottle?”