* Found in animal foods and converted from beta-carotene in plant foods.
* Required for vision, gene expression, reproduction, embryonic development, red blood cell production, and immune function.
* Prescription vitamin A derivatives are used to treat skin conditions (acne) and retinitis pigmentosa (genetic eye disease).
* Defi ciency is rare in Canada, but common in developing countries due to malnutrition. It causes night blindness, dry eyes and skin, and impaired growth.
* Drugs that deplete vitamin A: cholestyramine, colestipol, mineral oil, and neomycin.
* Supplements should be avoided by those at risk of lung cancer (smokers) or liver toxicity (alcoholics, liver disease).
* Doses greater than 10,000 IU daily should be avoided by pregnant women due to the risk of birth defects. Most prenatal vitamins provide 5,000 IU.
* Doses greater than 5,000 IU may increase risk of osteoporosis.
* Supplements of vitamin A beyond what is provided in a multivitamin are not recommended due to risk of toxicity. To avoid this risk, choose a multivitamin that contains beta-carotene, which is converted to vitamin A in the liver, but is not associated with health risks.