Vitamin D - Learn About Vitamins & Minerals
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.
What food source is the nutrient found in?
The most reliable source of vitamin D, in the US diet, is fortified
milk. All milk sold in the United States is fortified with vitamin
D. Vitamin D is also present in:
- some soy milks
- fish such as sardines and salmon
- cod liver oil
- fortified cereals
Vitamin D is called the sunshine vitamin. This is because the body
can make vitamin D after sunlight, or ultraviolet light, hits the
skin. Ten to 15 minutes of sun exposure 3 times a week is all the
body needs. Older people are less efficient with this conversion.
How does the nutrient affect the body?
Vitamin D helps build strong and healthy bones and teeth. It does
this by helping the body to absorb the minerals calcium and phosphorous
and to deposit them in bones and teeth.
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
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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