Glucosamine is an amino acid derivative of glucose that plays a key role in the production of cartilage and other joint tissues. Supplemental glucosamine is derived from chitin, the processed exoskeleton of shrimp and crabs. Available forms include glucosamine sulfate, N-acetyl-glucosamine, and glucosamine hydrochloride. Glucosamine sulfate is generally considered the preferred form, and it is the form used in most scientific studies.
The role of glucosamine in the body is to provide the raw material for and to stimulate the production of key structural components of joint cartilage. It is often taken in combination with chondroitin sulfate, a closely related compound.
Most studies on glucosamine sulfate have used a total daily dosage of 1,500 mg, usually divided into three 500 mg doses. Glucosamine is generally well tolerated at this dosage. Side-effects, when reported, have mostly been mild to moderate gastrointestinal symptoms such as heartburn, diarrhea, indigestion, and nausea. Taking glucosamine with food may help minimize adverse effects.