A review on the effects of glucosamine for knee osteoarthritis based on human and animal studies

Glucosamine (GlcN) is a popular nutritional supplement/prescription for relieving symptoms of osteoarthritis (OA), particularly for the knee joint. Although there are certain studies reporting the positive effects of GlcN for OA, its use remains controversial and the mechanism behind is unclear. This article critically reviewed published papers on the effects of GlcN in human clinical trials and animal studies. Twelve human clinical studies were reviewed and half of the studies reported positive effects of GlcN for OA or regular knee pain. Eight animal studies were reviewed and most of them had involved histological examination of cartilage, glycosaminoglycan content, subchondral bone, and synovium. Besides, nociceptive behaviour, biochemical markers, and immunohistochemistry of the joints were also examined. There is some evidence showing the beneficial effects of GlcN on joint structural repair in animals, but further research is needed to confirm the applicability of these models in human.