Glucosamine is a natural compound that is found in healthy cartilage. Glucosamine sulfate is a normal constituent of glycoaminoglycans in cartilage matrix and synovial fluid.

Available evidence from randomized controlled trials supports the use of glucosamine sulfate in the treatment of osteoarthritis, particularly of the knee. It is believed that the sulfate moiety provides clinical benefit in the synovial fluid by strengthening cartilage and aiding glycosaminoglycan synthesis. If this hypothesis is confirmed, it would mean that only the glucosamine sulfate form is effective and non-sulfated glucosamine forms are not effectiv