Microcrystalline Hydroxyapatite (MCHA) is a compound that normally makes up the crystalline matrix of bone and teeth and is the substance that gives them their rigidity.* MCHA contains highly absorbable calcium and phosphorus, which are the major mineral components of bone.* NOW® Bone Strength„¢ is a comprehensive bone support product with MCHA.* It also provides magnesium and other important minerals, as well as vitamins C, D, and K to aid in the synthesis and maintenance of bone tissue.* NOW® Microcrystalline Hydroxyapatite (MCHA) is derived exclusively from Australian cattle. Natural color variation may occur in this product.