Vitamin A
A fat-soluble vitamin essential for vision, immunity, and skin.
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What it is
Vitamin A comes as preformed retinol (from animal foods) and as beta-carotene (from colorful plants, which the body converts). It's essential for vision — especially in low light — and for immune and skin health.
How it works
Vitamin A is essential for vision (it forms the light-sensing pigment in the retina, crucial for low-light sight), immune function, skin and cell growth, and reproduction. It comes preformed as retinol from animal foods, and as beta-carotene from plants, which the body converts to vitamin A as needed. Being fat-soluble, it's stored in the liver, so excess can accumulate.
What it's been studied for
Used to support normal vision and skin, mainly where dietary intake is inadequate.
What the evidence shows
Vitamin A is essential and deficiency impairs vision, but most people in well-fed populations get enough from food. Supplementing beyond needs offers little benefit and carries real risk at high doses.
Who should consider it
Most people in well-fed populations get enough from food, so routine supplementing isn't needed. Deficiency is a concern in some developing regions and with fat-malabsorption conditions. It appears in eye and multivitamin formulas, often as beta-carotene. Preformed vitamin A needs particular caution in pregnancy.
Amounts commonly studied
Daily needs are modest (around 700-900 mcg RAE for adults). Beta-carotene forms don't carry the same toxicity risk as preformed retinol.
How to take it
Daily needs are modest (about 700-900 mcg RAE for adults), usually met by diet. If supplementing, beta-carotene forms don't carry the same toxicity risk as preformed retinol. Take fat-soluble vitamin A with a meal, and avoid stacking multiple products that each contain retinol.
Forms & absorption
Retinol/retinyl esters (preformed) or beta-carotene (provitamin). Many eye and multivitamin formulas use beta-carotene.
Food sources
Preformed vitamin A (retinol) is in liver, fish, eggs, and dairy. Beta-carotene is in orange and dark-green produce — carrots, sweet potato, pumpkin, spinach, and kale.
Safety & interactions
Preformed vitamin A is fat-soluble and toxic in excess — do not exceed upper limits, and it's especially important to avoid high doses in pregnancy, where it can cause birth defects. High-dose beta-carotene may raise lung-cancer risk in smokers.
Myths & what it won't do
Myth: more vitamin A means better eyesight. Reality: it prevents deficiency-related night blindness, but extra beyond adequacy doesn't sharpen normal vision. Myth: all vitamin A is equally safe. Reality: preformed retinol is toxic in excess and, importantly, high doses can cause birth defects — so it must be limited in pregnancy.
Common questions
- Retinol or beta-carotene?
- Beta-carotene is safer for general supplementing because the body converts only what it needs, avoiding retinol's toxicity risk. Preformed retinol works but is easier to overdo.
- Is vitamin A safe in pregnancy?
- Prenatal-level amounts are fine, but high-dose preformed vitamin A (retinol) can cause birth defects and must be avoided — confirm your prenatal's form and dose with your provider.
- Can beta-carotene be harmful?
- Usually it's safe (excess just tints skin harmlessly), but high-dose beta-carotene supplements have been linked to higher lung-cancer risk in smokers, who should avoid them.
The amounts listed here are what published research has used — not a prescription or a recommended dose for you. Confirm anything you plan to take with your own healthcare provider, especially if you take medications, are pregnant or nursing, or have a health condition.
Related goals
Research on Vitamin A
Recommendations on this page are informed by published research. This is educational information, not medical advice.
- Penniston KL, Tanumihardjo SA. The acute and chronic toxic effects of vitamin A. Am J Clin Nutr. 2006;83(2):191-201. View study →Note: Reviews the acute and chronic toxic effects of too much preformed vitamin A (retinol), including from supplements.