It clearly stated and addressed a focused clinical question. The validity of each trial included in the review was assessed and the methods clearly reported. Assessments of studies were reproducible with a good level of inter-rater agreement. Results of the quality assessment strongly suggest, however, that these beneficial therapeutic effects are likely exaggerated because of serious methodologic flaws and biases in the available literature. This might be attributable to the high level of manufacturer affiliation and support involved in these studies, which indicates the need for independently produced clinical trials.
Many questions remain unanswered.
This opinion, however, is based on results from trials of relatively short duration. To date, no real long-term data support these conclusions. As well, preparations made by different manufacturers might contain different concentrations of these compounds, and could have different efficacy and side effect profiles. Currently, the trend is 500 mg of glucosamine and 400 mg of chondroitin three times daily. As confirmed in this review, it could take more than 1 month before the full therapeutic effect is achieved.