Vitamin D is a fat-soluble vitamin that is used by the body in the absorption of calcium. Vitamin D promotes the body's absorption of calcium, which is essential for the normal development and maintenance of healthy teeth and bones. Calcium is also important to nerve cells, including the brain. Vitamin D also helps maintain adequate blood levels of calcium and phosphorus. Vitamin D is found in the following foods: Dairy products ( Cheese,Butter,Cream,Fortified milk (all milk in the U.S. is fortified with vitamin D), Fish, Oysters, Fortified cereals, Margarine.