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 and margarine
Cream
Fortified milk (all milk in the United States is fortified with vitamin D)
Fish
Oysters
Fortified cereals

Excessive doses of vitamin D can result in increased calcium absorption from the intestinal tract. This may cause increased calcium resorption from the bones, leading to elevated levels of calcium in the blood. Elevated blood calcium may then cause calcium deposition in soft tissues such as the heart and lungs. This can reduce their ability to function.
Kidney stones, vomiting, and muscle weakness may also occur due to the ingestion of too much vitamin D.

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.

Many people think that if some vitamins are good, a lot is better.
This is not always the case, and high doses of certain vitamins are actually toxic.
Read about the specific vitamins and check with your health care provider if you are unsure about how much to take -- and how much may be too much.

The best way to get the daily requirement of essential Vitamin D is to eat a balanced diet that contains a variety of foods and take a "Standardized" (quality) multivitamin supplement.