Vitamin & Mineral Guide: Vitamin A

Maintains the immune system; protects eyesight; keeps skin and tissues of the digestive tract and respiratory system healthy; antioxidant.

How Much: Recommended daily allowance (RDA) = 3,000 International Units (IU) for men; 2,333 IU for women.

Too Much: Upper limit (UL) = 10,000 IU from retinol, but half that amount may increase the risk of fractures.

Too Little: Rare; night blindness and weakened immune system.

Foods: Beta-carotene: apricots, cantaloupe, carrots, dark leafy greens and sweet potatoes.  Retinol: cheese, liver, eggs and fortified milk.

Interactions: Cholestyramine (Questran), mineral oil, oral contraceptives and isotretinoin (Accutane.)

Research Note: A study suggests a form of vitamin A called all-trans-retinoic acid may be useful for treating autoimmune diseases, such as rheumatoid arthritis (RA)