NOW® Glucosamine Sulfate is a well-known joint support ingredient.* Glucosamine is an essential building block for the formation of glycosaminoglycans (GAGs) and proteoglycans the main components of cartilage tissue.* These compounds attract water to form a joint cushion providing lubrication and shock absorption.* NOW Foods developed the glucosamine test method chosen as the official AOACI industry standard method. Natural color variation may occur in this product.