Glucosamine
Naturally exists in the body, particularly in cartilage. It's also found in the shells of shellfish
Glucosamine is a natural compound found in cartilage — the tough tissue that cushions joints. In supplement form, glucosamine is harvested from shells of shellfish or made in a lab. There are several forms of glucosamine, including glucosamine sulfate, glucosamine hydrochloride and N-acetyl glucosamine.