Glucosamine (or glucosamine, in acronym GlcN) is a substance (amino sugar) present in various natural substances (chitins, glycoproteins, glycolipids, complex polysaccharides, etc.) and involved in the synthesis of lipids and glycosylated proteins. There are different forms of glucosamine: the best known are glucosamine hydrochloride, glucosamine sulfate (glucosamine-N-sulfate, present in heparin) and N-acetylglucosamine (present in hyaluronic acid). It has several properties attributed to it: the main one concerns its potential joint strengthening activity and would help preserve the structure and degree of elasticity of the cartilage. According to some studies, moreover, glucosamine would support the organism in case of intense physical and mental work and it would have anti-inflammatory activities.