Nutraceuticals: do they work and when should we use them?

There are numerous biological mechanisms by which nutritional factors might be expected to exert favorable influences on pathophysiological processes in osteoarthritis. Such processes include oxidative damage, cartilage matrix degradation and repair, and chondrocyte function and responses in adjacent bone. Micronutrients for which preliminary evidence of benefit exists include vitamin C and vitamin D. In addition, numerous nutraceuticals that may influence osteoarthritis pathophysiology--including glucosamine, chondroitin, S-adenosylmethionine, ginger and avocado/soybean unsaponifiables--have been tested in clinical trials. These products are safe and well tolerated, but interpretation of the collective results is hampered by heterogeneity of the studies, inconsistent results, and the conundrum of how to reconcile an apparent structural benefit with absence or modest effect on symptoms.