Our conclusion, after reviewing eight randomised trials, was that there existed a body of evidence supporting the use of glucosamine in arthritis. Since that time there have been two more systematic reviews published, and one superb three year study, all of which support the original conclusion. Now is a suitable time to update our knowledge, in part because the efficacy of glucosamine remains one of those questions asked most often by professionals and by the public. There are a few points that need to be borne in mind when examining trials of glucosamine for arthritis. Glucosamine is usually in the form of the sulphate, but this formulation will contain other salts and some water of crystallisation, the actual amount of glucosamine may vary from preparation to preparation, stability may be a problem, and glucosamine may be in combination with chondroitin.
Doses used also vary, as do the number of times a day oral tablets are taken.
Usual oral doses are about 1 to 1.5 grams a day. Though oral administration is most common, it has also been given by injection into a joint, and by intramuscular or intravenous injection. There is no substantial evidence that this makes any difference. Outcomes used in trials vary enormously, as is the norm in arthritis trials, especially older ones. This inhibits pooling of data in meaningful ways.