Glucosamine and chondroitin are the best-documented approaches for reducing pain, rebuilding cartilage and slowing OA progression. They often are used in tandem because of similar sugar molecules that exist naturally in joints' synovial fluid—the liquid sacks between bones. Although the chondroitin molecule is larger than glucosamine (some scientists believe it is too big to be effectively absorbed into the blood and joints when taken as a supplement), some studies show it may work even better than glucosamine. However, chondroitin is four times more expensive than glucosamine.
In a 14-study meta-analysis published in the Journal of the American Medical Association, researchers at the Arthritis Center at Boston University Medical Center concluded that current evidence supports safety and modest efficacy for both compounds in OA treatment. However, they noted that additional independent studies are needed to confirm these findings, and that physicians may not be as involved in prescribing them to patients because of confusion about wide variability in formulations and purity of preparations.1
There may be a good reason for this. When New York-based independent analytic lab ConsumerLab.com tested 25 major brands of glucosamine and/or chondroitin supplements recently, it found that nearly one-third did not contain the full amount of labelled ingredients. While all 10 of the glucosamine-only products passed the test, almost half of the glucosamine/chondroitin combination products did not pass because of low chondroitin levels.
1. McAlindon T. Glucosamine and chondroitin for treatment of osteoarthritis: a systematic quality assessment and meta-analysis. JAMA 2000 Mar15;283(11):1469-75.