Glucosamine is a naturally occurring amino sugar synthesized in the body from L-glutamine and glucose. Glucosamine stimulates the manufacture of glycosaminoglycans, important components of the cartilage needed for healthy joints. Aging people seem to lose their ability to produce a sufficient amount of glucosamine, and there are no food sources available. Commercial sources of glucosamine are from the exoskeleton of certain shellfish and are available as glucosamine sulfate, glucosamine hydrochloride, and N-acetyl-glucosamine. The sulfated form may most effectively incorporate sulfur into the cartilage.
Glycosaminoglycans and glycoproteins allow cells in tissues to hold together. They are necessary for the construction and maintenance of virtually all connective tissues and lubricating fluids in the body. In particular, N-acetyl glucosamine is the final form, which together with glucuronic acid, is polymerized to make the joint lubricant, hyaluronic acid.
Chondroitin sulfates provide the structural components of joint cartilage and facilitate the entry of glucosamine into joints. Chondroitin sulfates also inhibit free radical enzymes. Like glucosamine, chondroitin sulfate attracts water into the cartilage matrix and helps to stimulate the production of cartilage.