Glucosamine is an amino sugar and a prominent precursor in the biochemical synthesis of glycosylated proteins and lipids. Glucosamine is commonly used as a treatment for osteoarthritis, although its acceptance as a medical therapy varies.


Health effects
Oral glucosamine is commonly used for the treatment of osteoarthritis. Since glucosamine is a precursor for glycosaminoglycans, and glycosaminoglycans are a major component of joint cartilage, supplemental glucosamine may help to rebuild cartilage and treat arthritis. Its use as a therapy for osteoarthritis appears safe, but there is conflicting evidence as to its effectiveness

Use
A typical dosage of glucosamine salt is 1,500 mg per day. Glucosamine contains an amino group that is positively charged at physiological pH. The anion included in the salt may vary. Commonly sold forms of glucosamine are glucosamine sulfate and glucosamine hydrochloride. The amount of glucosamine present in 1500 mg of glucosamine salt will depend on which anion is present and whether additional salts are included in the manufacturer's calculation.[7] Glucosamine is often sold in combination with other supplements such as chondroitin sulfate and methylsulfonylmethane.

In the United States, glucosamine is not approved by the Food and Drug Administration for medical use in humans. Since glucosamine is classified as a dietary supplement, evidence of safety and efficacy is not required as long as it is not advertised as a treatment for a medical condition.In Europe, glucosamine is approved as a medical drug and is sold in the form of glucosamine sulfate

Safety

Clinical studies of glucosamine have consistently reported that glucosamine appears safe. Since glucosamine is usually derived from shellfish, those allergic to shellfish or who have kosher concerns may wish to avoid it. However, since glucosamine is derived from the shells of these animals while the allergen is within the flesh of the animals, it is probably safe even for those with shellfish allergy. Finally, in the United States, glucosamine is sold as a dietary supplement, so safety and formulation is solely the responsibility of the manufacturer.