What is Glucosamine? Glucosamine is a natural molecule made by the body, composed of glucose and an amine (nitrogen and two molecules of hydrogen). Research shows that glucosamine plays a key role in helping to keep all the joints the body lubricated and supple. It stimulates the manufacture of glycosaminoglycans, key structural components in cartilage which line the joints. Glucosamine also promotes the incorporation of sulfur into cartilage. Because of this effect, research shows that glucosamine sulfate is the most effective form.