Vitamin A
- Effective dose
- 700–900 mcg
- Evidence
- 4/5· Strong
Last updated June 1, 2026
What it is
Vitamin A is a fat-soluble vitamin essential for vision, immune function, cell growth, and reproduction. It comes in two forms: preformed vitamin A (retinol and retinyl esters) from animal foods, and provitamin A carotenoids such as beta-carotene from plants, which the body converts to retinol as needed. It is a core component of rhodopsin, the light-sensitive pigment in the retina.
Benefits
Adequate vitamin A maintains normal night vision, skin and mucosal barriers, and immune defenses, and correcting a deficiency restores these functions. The Recommended Dietary Allowance is 900 mcg RAE/day for adult men and 700 mcg RAE/day for adult women.
When to take it
Take with a meal containing fat to aid absorption of this fat-soluble vitamin. Use beta-carotene rather than preformed retinol if supplementing during pregnancy, and do not exceed the upper limit from combined food and supplements.
Side effects
Preformed vitamin A is toxic in excess: the Tolerable Upper Intake Level is 3,000 mcg/day, and chronic high intake causes headache, dry skin, joint pain, liver damage, and bone loss, while acute megadoses cause raised intracranial pressure. High preformed vitamin A is teratogenic, so doses above the UL must be avoided in pregnancy; beta-carotene does not carry this risk. Orlistat lowers absorption, and combining with oral retinoid drugs (acitretin, bexarotene) raises toxicity risk.
Sources
Products containing Vitamin A
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