Quick guide to Vitamin A
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- healthy eyes and vision
- growth, repair and cell differentiation
- health of epithelial cells
- protection against infection
- a healthy reproductive system
Absorption and metabolism
Fat is necessary for vitamin A absorption.
Deficiency
Symptoms include night blindness, xerophthalmia, dry skin, retarded growth, increased susceptibility to infection and cancer.
Sources
Good sources of pre-formed vitamin A include liver, butter, whole milk and egg yolks.
Daily recommended dietary intakes
- Men - 1000 mcg RE (3333 IU)
- Women - 800 mcg RE (2666 IU)
- Pregnancy - 800 mcg RE (2666 IU)
- Lactation - +500 mcg RE (1666 IU)
Toxic effects of excess intake
Symptoms include headaches; bone and joint pain; dry, itchy skin; and liver damage. High daily doses of vitamin A (above 3000 mcg RE) in pregnancy may cause birth deformities.
Therapeutic uses of supplements
Supplements are used to boost immunity; prevent cancer; treat skin disorders such as acne and psoriasis; and treat eye problems.
Interactions
Mineral oil laxatives, cholestyramine, colchicine and alcohol decrease vitamin A absorption.
Cautions
Supplements should not be taken with vitamin A-derivative acne drugs or broad spectrum antibiotics. Pregnant women should