For years, the dietary supplement glucosamine has been touted as an effective way to relieve the pain of osteoarthritis and slow or prevent joint deterioration. The rationale behind the claims for glucosamine—and for chondroitin, a supplement often combined with glucosamine—is straightforward: Both compounds are produced in the human body and are thought to play a role in the formation and maintenance of joint cartilage; they may also be involved in joint repair.
Glucosamine is often made from the shells of shrimp, crabs and oysters, while chondroitin is usually made from cow cartilage. The supplements are marketed to people with osteoarthritis based on the premise that they will reduce the loss of cartilage in joints and diminish joint pain.
Researchers have conducted dozens of studies on glucosamine, focusing primarily on its effect on knee pain, with conflicting results—but the best-designed studies have found, overall, that glucosamine, alone or in combination with chondroitin, works no better than a placebo. It’s also worth noting that many studies showing a benefit from glucosamine have been sponsored by companies that market the supplement. Still, some recent evidence suggests that glucosamine/chondroitin may be an option for certain people.
A closer look at pain relief
In 2006, a large, government-sponsored trial, the Glucosamine/ chondroitin Arthritis Intervention Trial (GAIT), was reported in The New England Journal of Medicine. The researchers randomly assigned nearly 1,600 people with knee osteoarthritis to receive one of the following:
• glucosamine (1,500 mg daily)
• chondroitin (1,200 mg daily)
• glucosamine and chondroitin in combination
• the prescription nonsteroidal anti-inflammatory drug (NSAID) celecoxib (Celebrex, 200 mg daily)
• a placebo
The chief finding: At six months, those taking a supplement had no greater pain relief than people who received a placebo. Indeed, it seemed, only participants in the celecoxib group reported less knee pain.
But there was an exception: In a subgroup of 354 individuals who had moderate-to-severe pain, rather than mild pain, 79 percent of those who received the combination supplement experienced significant pain reduction versus 54 percent of those who got a placebo.
Subsequently, the GAIT researchers followed 662 of the original participants who continued to take the supplements, celecoxib or placebo for two years. Findings from this analysis, published in 2010 in the Annals of the Rheumatic Diseases, showed that glucosamine was equal to celecoxib in reducing pain—though neither was significantly better than the placebo.
More recently, data from an international trial called MOVES were reported in 2015 in the Annals of the Rheumatic Diseases. Once again, researchers compared the glucosamine/chondroitin combination with celecoxib, this time in six hundred people who had severe pain from knee osteoarthritis.
This study—which used a high-dose prescription formulation of glucosamine/chondroitin provided by a Spanish company that manufactures it—found that the combination supplement and celecoxib were comparable in reducing pain, stiffness, functional limitations and joint swelling over six months with few side effects.
The finding that a prescription-strength combination of glucosamine and chondroitin—not currently available in the United States—had an equivalent effect to celecoxib in relieving osteoarthritis pain in a select group of patients is similar to the GAIT researchers’ 2006 results.
Taken together, findings from the two studies suggest that glucosamine plus chondroitin may be an option to consider for people with osteoarthritis who can’t take celecoxib or other NSAIDs, such as people with heart disease and other cardiovascular conditions. An important caveat: The GAIT researchers reported some adverse cardiovascular effects, but it is not clear how many may have been related to supplement use. The MOVES study did not report any adverse cardiovascular events, but patients with or at risk for heart disease were excluded from the study. Consequently, more research is needed to determine further risks and benefits.
Impact on cartilage
What about the claim that the supplements help prevent or slow cartilage loss? Study results have been mixed.
The Long-term Evaluation of Glucosamine Sulfate (LEGS) study, published in 2015 in the Annals of the Rheumatic Diseases, reported that joint space narrowing (a sign of cartilage loss) was significantly reduced in people who received glucosamine (1,500 mg) plus chondroitin (800 mg) once a day for two years compared with those who received a placebo.
Other studies, including a 2008 report from GAIT researchers and a study in the April 2014 issue of Arthritis & Rheumatology, showed no improvements. In the latter study, researchers recruited 201 men and women with knee osteoarthritis who had mild-to-moderate pain in one or both knees. At the start of the study, all participants underwent magnetic resonance imaging (MRI) of their affected knee to show how much cartilage had been lost.
Half of the participants drank a beverage containing 1,500 mg of glucosamine every day for six months, while the others received a placebo beverage with inactive ingredients. At the end of the study, repeat MRIs showed that cartilage loss was similar in both groups.
These varied results indicate that more research is needed to determine if glucosamine alone or with chondroitin has a meaningful effect on cartilage. Researchers would also need to determine the effective dosage and duration of treatment.
What about other joints?
The effects of glucosamine/chondroitin on joints other than the knee aren’t well-known because few well-designed, unbiased studies have focused on them. The only relatively extensive studies have been done on hip osteoarthritis, and just like those of knee osteoarthritis, the results are mixed. And there’s no conclusive evidence that glucosamine/chondroitin can relieve pain or improve function in other joints affected by osteoarthritis, such as the spine or hands.
Glucosamine and chondroitin are sold as a combination pill or separately. Since the Food and Drug Administration does not regulate dietary supplements, there is no guarantee that a particular product contains what’s listed on the label.
Although these supplements are generally considered to be safe, they can cause adverse effects in some people. Don’t use them if you take the anticoagulant warfarin (Coumadin). Glucosamine has the potential to raise blood glucose levels in people with diabetes. In addition, because glucosamine is derived from oyster shells, people who have shellfish allergies should avoid it.
Be aware that the supplements may do a bit of damage to your wallet. They can cost $20 or more a month, which may be a high price to pay for what could be a placebo effect. Keep in mind that in its most recent guidelines, the American College of Rheumatology does not recommend these supplements for knee (or hip) osteoarthritis. Still, if you already take one or both of them and get relief, some experts believe it’s probably OK to continue taking them—but you may want to consider stopping for a while to see whether there’s a difference.