400 IU Vitamin D + 100 mg Calcium Supports Teeth, Bone and Immune Health* Vitamin D is present in only a few kinds of foods which accounts for the fact that approximately 70% of the children in the United States maintain low levels of Vitamin D in their systems. To maintain an 'acceptable' level of Vitamin D supplemental amounts of this important vitamin must be introduced to the system on a regular basis. Children and adults require Vitamin D to maintain a healthy body. Vitamin D3 (cholecalciferol) is produced by the human body as a result of the skin being exposed to UVB rays from the sun. Vitamin D3 assist in the absorption of calcium and phosphorous from the dietary intake and transfers it to the bloodstream which is a significant aid in the building and maintenance of the skeletal system in general.