Clinical trials on glucosamine and chondroitin

There is a history of clinical research done on glycosaminoglycans, especially glucosamine and chondroitin, for the treatment of arthritis. Since glucosamine is a precursor for glycosaminoglycans, and glycosaminoglycans are major components of cartilage, ingesting glucosamine might nourish joints, and thereby alleviate arthritis symptoms.

Some of the evidence for the effectiveness of glucosamine is disputed. A 2008–2009 review of all known studies of glucosamine supplements for horses, for example, found that almost all studies had failed to meet usual standards and were fatally compromised by basic errors in their execution, including failure to test whether active ingredients were as stated, lack of adequate (or any) control groups or baseline measurements, very small sample sizes, and ignoring prior research or self-evident omissions. The authors highlighted confirmation bias as a significant issue in such studies, in that most studies were undertaken by manufacturers, on products they already produced commercially, and they were usually undertaken to support claims of benefits which could be used to market the product. More recently, other reviews found little evidence that glucosamine and chondroitin supplements were any better than a placebo or at most only slightly better.

Glucosamine sulfate may be efficacious in ways that glucosamine hydrochloride is not. The Osteoarthritis Research Society International advises arthritis sufferers to discontinue glucosamine therapy if they notice no benefit within six months and the National Institute of Clinical Excellence no longer recommends its use. Despite the difficulty in determining the efficacy of glucosamine, it remains a viable treatment option. Similar trials have been done with chondroitin.

...
Wikipedia