Glucosamine is now one of the top-selling dietary supplements in the United States. It is used by many older adults at risk for or suffering from osteoarthritis, a population that is exploding as baby boomers now enter their 50s and 60s, and as our expanding waistlines put more long-term pressure on our knees and hips.
Glucosamine is used to treat joint pain and other symptoms of osteoarthritis. It is usually packaged by itself or in combination with chondroitin. Suppliers of glucosamine and chondroitin claim that they reduce osteoarthritis pain, promote healthy joint function, and nourish joint cartilage. They are sold over the counter as nutritional supplements (and thus are not regulated by the FDA). Physicians also may prescribe or recommend a three-month trial of an oral glucosamine/chondroitin complex for patients with more severe knee or hip pain.
While there have been some anecdotal reports of benefit, and it is well established that the health risks associated with supplementation are low, real clinical evidence of glucosamine’s analgesic (pain relieving) and structural effects have thus far been inconclusive.
Glucosamine (a simple amino sugar) and chondroitin (a complex carbohydrate) are both integral parts of the structural carbohydrate chains that make up much of the cartilage in your joints. Supplement makers cite theories that the two substances inhibit the breakdown and inflammation of cartilage while improving its elasticity. There is evidence that this is true of the naturally-occuring glucosamine and chondroitin in your body.
What is unknown is how much supplemental glucosamine or chondroitin can help. Glucosamine is generally absorbed well by your digestive tract, but a lot of it is broken down in the liver before it has a chance to reach your joints. Chondroitin is a much larger molecule that doesn’t seem to be absorbed well, and when the two are taken together, chondroitin may inhibit the absorption of glucosamine. Studies evaluating the efficacy of the supplements have had conflicting results.
Most of the early trials evaluating glucosamine or chondroitin were limited by short durations, small sample sizes, and even sponsorship bias. The recent research standard is the Glucosamine/Chondroitin Arthritis Intervention Trial (GAIT), funded by the National Institutes of Health (NIH). For six months, subjects (average age of 59) blindly received standard doses of one of five treatments- 1500 mg glucosamine, 1200 mg chondroitin, 1500 mg glucosamine/1200 mg chondroitin together, 200 mg celecoxib (a non-steroidal anti-inflammatory drug) or placebo. Overall, with regard to pain reduction and joint function, glucosamine and chondroitin were not significantly effective over placebo, alone or in combination (celecoxib, on the other hand, provided significant pain relief). For a subset of patients with moderate-to-severe pain, the glucosamine/chondroitin combination did lower pain compared to placebo, although the significance of the finding is weakened by the subset’s small sample size. Further confusing the result was the fact that the form of glucosamine used was glucosamine hydrochloride, not glucosamine sulfate, the common form of the supplement.
Longer-term follow ups within the GAIT study have evaluated both pain and structural changes in the knee joint and have still not found clinical improvements in patients using the supplements.
A few recent studies evaluating glucosamine (sulfate) and chondroitin by themselves have had more promising results. Two three-year trials examining glucosamine found improvements over placebo for both pain and joint structure, and a pair of two-year chondroitin studies found that the supplement helped maintain joint integrity (although pain was not reduced). It may be that an oral glucosamine/chondroitin combination supplement simply does not make its way to your joints the way that either individual dose does, because of absorption or metabolism issues. One recent study applying the combination as a topical cream to the knee showed some pain relief, but more research needs to be done using this method.
Until then, if you have at least moderate arthritis pain and you’re willing to spend on it, a 3-month trial or so wouldn’t hurt, as the risks are very low. Just remember that the evidence is inconclusive so far. Try an individual glucosamine sulfate (1500 mg dose) or chondroitin sulfate (1200 mg dose) supplement over the combination and you may give yourself a better shot. As always, be on the safe side and consult your doctor or dietitian before initiating any new supplement regimen, particularly if you have impaired kidney or liver function.