Why are clinical trials of glucosamine no longer uniformly positive?

Abstract

In contrast to earlier industry-funded trials of for knee OA, recent studies have generated negative results. While there will be a tendency to assume that these studies were negative because of the absence of any conflicts of interest, a number of issues must be taken into consideration before drawing such conclusions. These issues include design issues and important differences in sample characteristics. Ultimately, it is clear that more work needs to be done to clarify issues surrounding the efficacy and utility of the various glucosamine compounds.