Glucosamine is the building block for proteoglycans, the molecules in cartilage which form the mesh network. Supplementing with glucosamine provides the body with additional raw material to make cartilage. It has been shown that increasing the amount of glucosamine available to cartilage stimulates increased production of cartilage. Glucosamine is absorbed orally and will preferentially be taken up by the joints. Oral supplementation with glucosamine is very safe.