How Glucosamine & Chondroitin Sulfate Work: Glucosamine is a basic building block for cartilage, synovial fluid and other connective tissue. It is needed for healthy structure and function of joints for optimum mobility.* Chondroitin Sulfate protects existing cartilage and serves as a building block for healthy new cartilage.* *These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure or prevent any disease.