Among the Missing: Vitamin D

Vitamin D is essential to help your body absorb and use calcium to help build strong bones and teeth, says the Office of Dietary Supplements (ODS). It also helps your body maintain a normal level of phosphorus. Without vitamin D, bones can become thin, brittle or misshapen. Vitamin D sufficiency prevents rickets in children and osteomalacia in adults, two forms of skeletal diseases that weaken bones.

These are sources of vitamin D:

• Foods fortified with vitamin D, including cereals and milk. (Note: Dairy products made from milk, such as cheese and ice creams, usually are not fortified with vitamin D.)

• The ultraviolet rays of the sun. Sun exposure is the way most people get all the vitamin D they need each day.

The ODS says you may develop a deficiency of vitamin D:

• If you don't get enough vitamin D in your diet.

• If you don't get out in the sun.

• If your kidneys can't convert vitamin D to the form your body needs.

• If your body can't adequately absorb vitamin D.

Good day, sunshine

You don't need to be out in the sun long to get enough sunlight to help your body make vitamin D. You'll get enough if you spend 10 to 15 minutes outdoors between 8 a.m. and 4 p.m. two to three days a week, the ODS says. The sunlight stimulates a hormone in your body to make vitamin D.

Unfortunately, even if you spend the right amount of time outdoors, you can't always get enough sunlight. In many parts of the country, the sun doesn't shine intensely enough in the winter months to help our bodies make vitamin D.

Cloud cover, air pollution, altitude and a person's skin color also affect the amount of sunshine available to the body. Sunscreens can block the amount of sunshine reaching the skin, as well.

Aging and vitamin D

Older adults also have problems making enough vitamin D because older skin is less efficient at using the sunshine, the ODS says. In fact, elderly Americans are highest risk for vitamin D deficiency because of that. They also often don't eat enough foods that contain vitamin D and they take medications that interfere with the body's production of the vitamin.

The current ODS guidelines for daily vitamin D intake are 200 international units (IU) for people 19 to 50, 400 IU for those 51 to 70 and 600 IU for those 71 and older.

Other than the sun, the best way to get vitamin D is by drinking milk or eating cereals that have been fortified with the vitamin. One cup of fortified milk contains 100 IU. Eggs, fatty fish and liver contain some vitamin D, but they are also high in cholesterol or fat. One serving of a fortified cereal can provide the full daily requirement for vitamin D.

Don't take a vitamin D supplement until you have discussed it with your health care provider. Too much vitamin D can be toxic.