Glucosamine is an amino sugar and a prominent precursor in the biochemical synthesis of glycosylated proteins and lipids. A type of glucosamine forms chitin, which composes the exoskeletons of crustaceans and other arthropods, cell walls in fungi and many higher organisms. Glucosamine is one of the most abundant monosaccharides. It is produced commercially by the hydrolysis of crustacean exoskeletons or, less commonly and more expensive to the consumer, by fermentation of a grain such as corn or wheat. This is commonly used as a treatment for osteoarthritis, although its acceptance as a medical therapy varies. Glucosamine was first identified in 1876 by Dr. Georg Ledderhose, but the stereochemistry was not fully defined until 1939 by the work of Walter Haworth.
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. A randomized, double-blind, placebo-controlled trial found glucosamine sulfate is no better than placebo in reducing the symptoms or progression of hip osteoarthritis. A typical dosage of glucosamine salt is 1,500 mg per day. This contains an amino group that is positively charged at physiological pH. The anion included in the salt may vary. Commonly sold forms of this are glucosamine sulphate 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. Glucosamine is often sold in combination with other supplements such as chondroitin sulfate and methylsulfonylmethane.
Glucosamine is a popular alternative medicine used by consumers for the treatment of osteoarthritis. Glucosamine is also extensively used in veterinary medicine as an unregulated but widely accepted supplement. The benefit of glucosamine sulfate in patients with osteoarthritis is likely the result of a number of effects including its anti-inflammatory activity, the stimulation of the synthesis of proteoglycans, and the decrease in catabolic activity of chondrocytes inhibiting the synthesis of proteolytic enzymes and other substances that contribute to damage cartilage matrix and cause death of articular chondrocytes.