Glucosamine is a molecule similar to glucose that is naturally found in the body. It is a precursor (one of the building blocks) of glycosaminoglycans (e.g. hyaluronic acid, keratan sulphate and heparansulphate), which are major constituent molecules of connective tissues, including cartilage and joint tissues. When attached to proteins, they form proteoglycans. These contribute to the properties of joint cartilage, which cushions joints, redistributes loads and minimises friction during movements between two joint surfaces. Glucosamine therefore helps keep the joints in good condition and contributes to joint comfort.
With age, cartilage can gradually deteriorate; it becomes less resistant and its role of shock absorber and supporter of joint mobility becomes compromised. This creates a real vicious circle, because the deterioration of cartilage releases substances that sustain this deterioration and joint movements become more and more uncomfortable.