Glucosamine is a monosaccharide or simple sugar that’s naturally produced by the body. It’s an important component of connective tissues, including joint cartilage, helping to form a protective “cushioning” layer between bones. Since Glucosamine is a precursor for glycosaminoglycans and glycosaminoglycans are a major component of joint cartilage, supplemental Glucosamine may help to rebuild cartilage. Chondroitin sulfate attracts and holds large amounts of water to the cartilage-building proteoglycan molecules. Since cartilage has no blood supply, this fluid is necessary to nourish and lubricate joints.