the calcium content of the human body is about 1200g, of which 99% is found in bones and teeth in the form of hydroxyapatite crystals. Chemically synthesized hydroxyapatite is white and tasteless, safe to eat; The particle size is small, the specific surface area is large, and the ability to bind to proteins (bacteria contain proteins) and pigments is strong, and the biocompatibility is strong. The chelating force and acid-base buffering force of metal ions are stronger than other phosphates. It has a good calcium supplementation effect, easily promotes the deposition of calcium in the body on the bones, inhibits bone absorption, increases bone density, and ensures the growth of bone calcification.