Definition
Vitamin D is a fat-soluble vitamin that is used in the absorption of calcium.

Function
Vitamin D promotes the body's absorption of calcium, which is essential for the normal development of healthy teeth and bones. It also helps maintain adequate blood levels of the minerals calcium and phosphorus.

Food Sources
Vitamin D is found in cheese, butter, margarine, cream, fortified milk (all milk in the United States is fortified with Vitamin D), fish, oysters, and fortified cereals.

Side Effects
A vitamin D deficiency leads to soft bones or rickets.

Large doses of vitamin D can result in increased calcium absorption from the intestinal tract, and possibly also to increased calcium resorption from the bones, leading to elevated levels of calcium in the blood.?This can lead to abnormal calcium deposition in soft tissues, such as the heart and lungs, reducing their ability to function.

Recommendations
Recommended daily allowances (RDAs) are defined as the levels of intake of essential nutrients that, on the basis of scientific knowledge, the Food and Nutrition Board judges to be adequate to meet the known nutrient needs of practically all healthy persons.

The best way to get the daily requirement of essential vitamins is to eat a balanced diet that contains a variety of foods from the food guide pyramid.

Vitamin D is also known as the sunshine vitamin because the body manufactures the vitamin after being exposed to sunshine. Ten to 15 minutes of sunshine 3 times weekly is adequate to produce the body's requirement of vitamin D.

Specific recommendations for each vitamin depend on age, gender, and other factors (such as pregnancy).