About Vitamin A
Exists as preformed retinol (animal sources) and provitamin A carotenoids like beta-carotene (plant sources). Retinyl palmitate and retinyl acetate are common supplemental forms with high bioavailability. Preformed vitamin A carries toxicity risk at high doses—excess can cause liver damage and is contraindicated in pregnancy above the RDA. Beta-carotene is non-toxic as the body regulates its conversion, but it converts inefficiently (12:1 ratio).
What Vitamin A supports
- Supports healthy vision
- Maintains skin integrity
- Enhances immune function
How much Vitamin A to take
Clinical studies typically use 700–1500 mcg of Vitamin A.
- RDA
- 900 mcg
- Upper limit (UL)
- 3000 mcg
- Effective range
- 700–1500 mcg
Forms of Vitamin A compared
- Retinyl palmitateStandardPreformed vitamin A; readily absorbed without conversion.
- Retinyl acetateStandardPreformed vitamin A ester; equivalent to palmitate in studies.
- Beta-carotene (provitamin)BudgetProvitamin A — conversion is highly variable; 2–28% of users are poor converters.
Clinical evidence
Strong clinical evidence. Essential for vision via retinal pigment formation; toxicity risk above RDA in preformed retinol, not beta-carotene
NIH Fact Sheet