As a supplement, glucosamine is popularly taken to support the maintenance of healthy joint structure and function, helping the user to keep supple and flexible. In clinical trials glucosamine has been shown to have the ability to improve symptoms such as pain and stiffness in the joints, and has improved joint mobility in the context of wear and tear conditions. Glucosamine is a precursor to the building blocks that are needed for the formation of the cartilage that lines the joints. Although glucosamine is found in certain foods, it is not normally present in the diet in significant amounts, and supplements provide a practical and effective method of replenishing stores.