Glucosamine Sulfate is a naturally occurring chemical in the body. It is in the fluid around the joints. Joints are cushioned by cartilage and this fluid. Osteoarthritis occurs when the cartilage breaks down and becomes thin causing pain and stiffness. Glucosamine supplements can increase the cartilage and/or the fluid around the joints. The “sulfate” is important because the body needs it to produce cartilage.