Pure Okinawa Source With Trace Minerals Plus Vitamin D. The Coral Calcium used in this product is derived from an above sea coral off the shores of Okinawa Japan. The method used to mine the coral in this product does not destroy living coral reefs. It contains approximately 70 naturally occurring trace minerals in varying amounts. The addition of 400 IU Vitamin D is intended to work synergistically with calcium to help enhance calcium absorption. The calcium in this product is intended to provide nutritive support for the development and maintenance of normal healthy bones and teeth proper nerve impulse transmission and muscle contraction.