Vitamin A
Commonly used for
ImmunityHealthy Aging
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The cheapest product is usually low quality, but more expensive doesn’t always mean better.
What is it? / Overview
Vitamin A is essential for vision, immune function, and maintenance of healthy skin and mucous membranes. Supplementation is highly effective for correcting deficiency but should not be used routinely because excessive intake can cause serious toxicity.
How is it used? / Administration
Form: Retinyl palmitate or retinyl acetate (preformed); beta-carotene only when appropriate
Typical dose studied: 700 mcg RAE/day (women), 900 mcg RAE/day (men); do not exceed 3,000 mcg RAE without medical supervision
Timing: With fat-containing meal
Avoid chronic high-dose supplementation unless treating documented deficiency. Smokers should avoid high-dose beta-carotene due to increased lung cancer risk demonstrated in clinical trials. Excessive preformed vitamin A is teratogenic and should be avoided in pregnancy -- worth stating plainly even though the platform's own intake flow already hard-blocks recommendation generation for anyone reporting current pregnancy, since this guide page is also directly browsable outside that flow.
How well does it work? / Evidence
✓ Well-established
Who should avoid it?
Avoid with: End-stage liver disease / Cirrhosis
Interacts with: Retinoid medications (isotretinoin, acitretin); Orlistat may reduce absorption
Already taking it? Calculate total intake from multivitamins and cod liver oil to avoid toxicity.
Research & references
Sommer A, Vyas KS. (2012). Global clinical view on vitamin A. American Journal of Clinical Nutrition. Andrès E et al. (2024). Fat-soluble vitamins A D E K review. Journal of Clinical Medicine. NIH Office of Dietary Supplements: Vitamin A Fact Sheet.
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