•  Bilberry

Vitamin A helps you see in the dark. In particular, it helps your eyes adjust to darkness after being exposed to bright light, like the headlights of an oncoming car at night. You can also thank vitamin A for healthy skin, strong bones, and a sound immune system. The vitamin itself shows up primarily in organ meats, but many fruits and veggies contain beta-carotene and other carotenoids that are converted to vitamin A in the intestine. Eating foods rich in these substances may protect you against heart disease and certain forms of cancer.

Women need 700, and men 900 micrograms of vitamin A each day. You can get most or even all of it from carotenoids, the orange and yellow pigments in vegetables and fruits. Six milligrams of beta-carotene--the amount in one large carrot--converts to 1,000 mcg of vitamin A in the body. No one knows how much beta-carotene you need to ward off heart disease or cancer, but eating five to nine servings of fruits and vegetables a day should provide you with a rich selection of carotenoids, which may all work together to keep you healthy.

The signs include dry skin, susceptibility to infections and night blindness. In children, a deficiency may contribute to slow bone development, retarded growth and increased risk of respiratory and viral infections.

Orange, red, and dark green vegetables and fruits are particularly rich in beta-carotene and the 50 other carotenoids that the body converts to vitamin A. Just one red bell pepper or half a cup of spinach contains enough to meet your daily requirement for A. But the more carotenoids you get, the better, so don't be afraid to load up on the produce!

Liver is by far the richest source of vitamin A itself. Fish and egg yolks are also packed with it, and milk is usually fortified with A because it helps your bones absorb calcium.

In the majority of cases, no. The Institute of Medicine recommends against beta-carotene supplements for the general population. In the United States few people suffer from A deficiency unless they are poor, and A supplements in the form of retinol (not beta-carotene) can easily give you a toxic dose. Supplements also won't give you all the health benefits of carotenoid-rich foods, and researchers in Finland found that smokers who took beta-carotene supplements were slightly more likely to develop lung cancer. However, because some U.S. children who live below the poverty level or are recent immigrants may suffer a slight A deficiency, the American Academy of Pediatrics recommends vitamin A supplements for children 6 to 24 months old hospitalized with measles and children older than 6 months who may have a slight vitamin A deficiency. People who have chronic problems absorbing fat may also need A supplements.

Yes. As little as 3,000 mcg of A a day (or 10,000 IU) in the form of retinol (not beta-carotene) can cause birth defects in pregnant women and, over time, headaches, hair loss, and liver damage. But unless you're eating a lot of liver, it's hard to get that much from your diet. You can't overdose on carotenoids, and your body will only convert what it needs to vitamin A.

Further Resources

Roberta Larson Duyuff, MS, RD, CFCS, The American Dietetic Association's Complete Food &Nutrition Guide. Chronimed Publishing, 1996, 1998.

References

First published September 30, 1998
Last updated December 14, 2007
Copyright © 1998 Consumer Health Interactive and OneBody, Inc.

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