Vitamin D is needed for growth and for the forming of bones. It controls the amount and placement of calcium and phosphorus (bone-building minerals) throughout the body. The popular name for vitamin D is “the sunshine vitamin.”
When your body is exposed to the ultraviolet rays of the sun, an oily substance in the skin is converted to vitamin D and subsequently transferred to the blood stream. However, according to one study, people with heavily pigmented skins may be prevented from assimilating up to 95 percent of vitamin D. It is the only vitamin that is also created in the body from another bodily substance. Vitamin D is unique in being not only a vitamin but also a hormone.
Our greatest need for vitamin D is during the growth years. To assure that children, teenagers, and pregnant and breast-feeding women meet their needs, milk is fortified with 400 IUs of vitamin D per quart, equivalent to 10 micrograms of cholecalciferol. Since milk also supplies calcium and phosphorus, and contains fat to help the body utilize vitamin D, it is the ideal food to promote the development of strong, healthy bones. Children who are strict vegetarians and eat no animal protein (including milk products) are particularly prone to rickets.