Supplemental glucosamine: Glucosamine is a 2-amino derivative of glucose which is obtained through the hydrolysis of chitin, a polysaccharide found in the shell of crustaceans. Crustaceans have a very high concentration of chitin and because the shells are often discarded, provide a reliable and cost effective source of glucosamine.
Chondroitin: Chondroitin is a naturally occurring product found in animal cartilage. Supplemental chondroitin is derived primarily from bovine (cow) cartilage, particularly the cartilage rings of the trachea. It is also derived from shark and whale cartilage. The source does not appear to have any impact on its effect. Though for ecological reasons, many consumers prefer bovine sources.