Skepticism for glucosamine to treat OA pain.

In recent years, glucosamine has enjoyed popularity as an effective treatment for osteoarthritis (OA), which currently affects over 20 million Americans. The over-the-counter supplement contains an amino sugar compound found in cartilage. The theory is that glucosamine (often paired with chondroitin, which in its natural form promotes cartilage elasticity) preserves and repairs the cartilage in arthritic joints. How exactly the body processes this extra glucosamine and chondroitin, and whether they are even delivered to the joints, remains unknown. Until recently, the clinical data on the effectiveness of glucosamine was limited to small studies or studies sponsored by the manufacturers themselves.

At last a large and independent study has emerged from the National Institutes of Health, and the preliminary verdict on glucosamine supplements is that they do not live up to manufacturers' claims. The so-called GAIT study involved nearly 1,600 patients with OA in their knees. The participants were assigned to six months of one of the following daily: 1,500 mg of pharmaceutical-grade glucosamine; 1,200 mg of chondroitin; the two together in these same doses; 200 mg of celecoxib; or placebo. Results were determined by asking patients to report the intensity of their pain on a scale of one to five.

The best results were obtained on the celecoxib regimen. The other three groups were overall no better off than the placebo group. The placebo effect is known to be particularly strong in OA studies, which can complicate the measuring of results. The combination of the debilitating nature of OA pain and its limited treatment options is thought to bring to these studies an unusual hopefulness that the drugs will work. Indeed, the one ray of hope for glucosamine/chondroitin in the GAIT study was that in moderate-to-severe sufferers the drugs outperformed placebo by 25%. Yet this same group saw no improvement over placebo with celecoxib, which has been shown to significantly reduce pain in numerous other studies, and significantly reduced pain in the other pain-level groups in the present study as well.

Glucosamine and chondroitin are thought to prevent cartilage loss, which is not the role of NSAIDs and COX-2 inhibitors such as celcoxib. Therefore, a study which focuses soley on pain reduction might not give us the whole story. A second phase of GAIT is underway that, through x-ray, will look for actual cartilage improvements in OA patients taking these supplements. (Cartilage does not appear on x-rays, but by measuring the space between the bone images, researchers can determine cartilage levels.)

The popularity of glucosamine and chondroitin can perhaps be traced to their availability without a prescription, as well as a lack of the side effects associated with many NSAIDs. As of now, however, it does not appear worthwhile for OA patients to continue supplementation if after a prolonged period they have not seen favorable results. Unsurprisingly, regular activity and weight management remain our staunchest allies in the battle against debilitating OA pain.

(Health After 50, The Johns Hopkins Medical Letter, 2006, Vol. 18, No. 5, pp. 1-2)