Vitamin D is essential to help your body absorb and use calcium to help build strong bones and teeth. 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 disease that weaken bones.
These are sources of vitamin D:
The best food sources of naturally occurring vitamin D are fatty fish, such as salmon and tuna. Beef liver, egg yolks, cheese, and mushrooms also provide small amounts of vitamin D.
Foods fortified with vitamin D, including cereals, milk, and soy or other milk alternative beverages. (Note: Dairy products made from milk, such as cheese and ice cream, usually are not fortified with vitamin D.)
The ultraviolet rays of the sun. Ultraviolet B rays help the body make vitamin D. Sun exposure is the way most people get all the vitamin D they need each day.
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.
If you are obese because body fat binds to some vitamin D and keeps it from getting into the blood.
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 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.
Older adults also have problems making enough vitamin D because older skin is less efficient at using the sunshine. 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 may take medications that interfere with the body's production of the vitamin.
The current recommendation from the Food and Nutrition Board for daily vitamin D intake are:
Birth to 12 months: 400 International Units (IU)
1-70 years: 600 IU
71 years and older: 800 IU
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.