Vitamin A
•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 reti-
nitis pigmentosa (genetic eye disease).
•Defi ciency is rare in Canada, but common in developing countries due to malnutri-
tion. 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 rec-
ommended 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 as-
sociated with health risks.
Tags: animal foods, Beta Carotene, blood cell production, cholestyramine, colestipol, dry eyes, embryonic development, gene expression, genetic eye disease, health risks, immune function, liver disease, liver toxicity, mineral oil, multivitamin, neomycin, night blindness, prenatal vitamins, red blood cell, skin conditions
