Articular cartilage is a connective tissue composed of specialized cells (chondrocytes) embedded in a matrix of protein fibers (mostly collagen) and clusters of complex proteoglycan molecules that consist of a protein core with numerous side chains. These side chains, chiefly chondroitin sulfate and keratin sulfate, are long polysaccharide molecules called glycosaminoglycans. Chondroitin sulfate (CS) and the other glycosaminoglycans strongly attract water due to the negative charges of their sulfate groups. These negative charges also repel each other, creating spaces between glycosaminoglycan side chains where water can enter. This combination of solid and liquid gives cartilage a compressible quality that allows it to function as a shock absorber for joints.
Glucosamine is a fundamental building block for proteoglycans and glycosaminoglycans. Glucosamine sulfate (GS) helps to maintain joint health through its ability to both act as a component of and stimulate formation of cartilage glycosaminoglycans and the hyaluronic acid backbone essential for the formation of cartilage proteoglycans.