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You are here : 3-RX.com > Medical Encyclopedia > Diet and Nutrition > Vitamin D
      Category : Health Centers > Food, Nutrition, and Metabolism

Vitamin D

Alternate Names : Cholecalciferol

Overview & Description | Functions and Sources

Vitamin D is a fat-soluble vitamin. It can be dissolved in fat. Vitamin D is carried through the body by fat and stored in fat tissue. Getting too much can be harmful. Vitamin D can be produced in the body, as well as, obtained from the diet.


If the body does not get enough vitamin D and calcium, a person is at higher risk for bone mass loss, which is known as osteoporosis. Low levels of vitamin D also increases the risk of bone softening, known as osteomalacia, in older adults. Children who do not get enough vitamin D over a long period may develop rickets, which is defective bone growth. Fortifying milk with vitamin D has made rickets extremely rare in the US.

Vitamin D is measured as micrograms (mcg) of cholecalciferol (koh-li-kal-sif-ah-rall). The Recommended Dietary Allowance, called RDA, for men and women, 25 to 50 years old, is 5 mcg per day. Children need twice as much daily vitamin D as adults, because their bones are still growing. Pregnant and lactating women also need 10 mcg per day.

Another common measurement for vitamin D is International Units, known as IU. The RDA, in IUs, for vitamin D for adults is 200 IU per day; for children, it is 400 IU per day; and for pregnant and lactating women, it is 400 IU.

In 1997, the recommendations were revised for vitamin D, doubling the amount for adults over age 50, going up to 400 IU or 10 mcg daily. People over age 70 need 600 IU or 15 mcg per day.

No one should have more than 2000 IU or 50 mcg per day of Vitamin D.

Because vitamin D dissolves in fat, it can build up in the fat tissues of the body. This can pose a problem for people taking high doses of vitamin D. While it is almost impossible to get too much vitamin D from foods or sunlight, it is easy to get too much from supplements. High doses of vitamin D can be toxic and cause:

  • kidney stones or damage
  • weak muscles
  • weak bones
  • excessive bleeding


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    Vitamin D: Functions and Sources

    Author: Clare Armstrong, MS, RD
    Reviewer: Kathleen A. MacNaughton, RN, BSN
    Date Reviewed: 09/30/02

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