Chondroitin is a naturally occurring substance formed of sugar chains. Chondroitin is believed to help the body maintain fluid and flexibility in the joints. Glucosamine is sugar protein that helps your body build cartilage (the hard connective tissue located mainly on the bones near your joints). Glucosamine is a naturally occurring substance found in bones, bone marrow, shellfish and fungus. Chondroitin and glucosamine is a combination product that has been used in alternative medicine as a possibly effective aid in treating osteoarthritis pain.