Glucosamine (C6H13NO5) is an amino sugar and a prominent precursor in the biochemical synthesis of glycosylated proteins and lipids. Glucosamine is found as a major component of the shells of crustaceans and other arthropods, in fungi and many higher organisms and is one of the most abundant monosaccharides. It is produced commercially by the hydrolysis of crustacean shells. Glucosamine is commonly used as a treatment for osteoarthritis, although its acceptance as a medical therapy varies.