Vitamin D contributes to the normal absorption/utilization of calcium and phosphorus. Vitamin D contributes to the maintenance of normal bones, muscle function, and teeth. Vitamin D contributes to the normal function of the immune system. Vitamin D has a role in the process of cell division. Vitamin D helps to reduce the risk of falling associated with postural instability and muscle weakness: falling is a risk factor for bone fractures among men and women 60 years of age and older.