Vitamin A

vitamin

Best with a mealTake with food

What is it

Vitamin A is a fat-soluble vitamin essential for vision, immune function, and cell growth. It exists as preformed vitamin A (retinol, retinyl esters) from animal foods and as provitamin A carotenoids (mainly beta-carotene) from plant foods.

How it works

Preformed vitamin A from animal sources is absorbed and stored in the liver as retinyl esters. When needed, it is released into the blood as retinol, then converted in cells to retinal (for vision) or retinoic acid (for gene regulation). Retinoic acid binds to nuclear receptors that control hundreds of genes involved in cell differentiation, immune function, and tissue development. Provitamin A carotenoids like beta-carotene are absorbed and converted to retinol in the intestinal wall, but conversion is regulated by the body — high intake does not cause vitamin A toxicity because conversion slows as needs are met. This is why vegetable sources are much safer than animal sources or supplements at high intakes.

Evidence for 5 uses

AI-assisted evidence assessment — talk to your doctor before relying on any single supplement.

Correction of vitamin A deficiency

Grade A

Strong evidence

Supplementation reverses deficiency, which causes night blindness, dry eyes, increased infection risk, and in severe cases keratomalacia and blindness. A major public health intervention in low-income countries.

Childhood mortality in low-income countries

Grade A

Strong evidence

WHO-supported high-dose vitamin A given to children in deficiency-prone areas significantly reduces all-cause mortality, especially from measles and diarrhea.

Measles outcomes

Grade A

Strong evidence

High-dose vitamin A given during measles infection in deficient children reduces complications and death.

Acne (topical retinoids)

Grade A

Strong evidence

Topical and oral retinoids are highly effective acne treatments. Oral vitamin A supplements are not a substitute and high doses are toxic.

Eye health (with AREDS formula)

Grade B

Good evidence

Beta-carotene was part of the original AREDS formula for AMD progression but was replaced with lutein/zeaxanthin in AREDS 2 due to lung cancer risk in smokers.

3 commercial forms

Retinol / retinyl palmitate (preformed)

highly bioavailable, stored in liver

Direct form found in animal foods and supplements. Easily toxic at high doses long-term. Most multivitamins contain modest amounts (around the RDA).

Beta-carotene (provitamin A)

regulated conversion, much safer

Plant-based precursor converted to retinol as needed. Does not cause vitamin A toxicity. Smokers should avoid high-dose beta-carotene supplements.

Cod liver oil

traditional source, also provides vitamin D

A traditional source providing both vitamins A and D. Watch total intake — modern cod liver oil products can deliver substantial vitamin A.

Dosage

The RDA is 900 mcg retinol activity equivalents (RAE) per day for adult men and 700 mcg RAE for women. Pregnant women need 770 mcg RAE; breastfeeding women need 1,300 mcg RAE. The tolerable upper limit is 3,000 mcg RAE (10,000 IU) per day for preformed vitamin A from supplements and animal foods. No upper limit exists for provitamin A carotenoids.

When and how to take it

Vitamin A is fat-soluble and absorbs best with a meal containing some fat. Time of day does not matter. Vitamin A stores in the liver — so daily, weekly, or even less frequent dosing can all maintain status, though daily is most practical. Avoid stacking vitamin A from multivitamins, multivitamins, and standalone supplements without tracking the total.

Food sources

Food	Amount	%DV
Beef liver, 3 oz cooked	6,582 mcg RAE	731%
Sweet potato (baked, with skin)	1,403 mcg RAE	156%
Spinach (boiled), 1/2 cup	573 mcg RAE	64%
Carrots (raw), 1/2 cup	459 mcg RAE	51%
Cantaloupe, 1/2 cup	135 mcg RAE	15%
Red bell pepper, 1/2 cup raw	117 mcg RAE	13%
Mango, 1 fruit	112 mcg RAE	12%
Egg, 1 hard-boiled	75 mcg RAE	8%
Cheddar cheese, 1 oz	75 mcg RAE	8%

Safety

Preformed vitamin A is one of the more easily toxic vitamins. Chronic intake above 3,000 mcg RAE per day can cause hypervitaminosis A: hair loss, dry skin, headache, bone pain, liver damage, and birth defects. Acute toxicity from very large single doses can cause increased intracranial pressure and vision problems. Most importantly, high-dose preformed vitamin A in pregnancy is teratogenic and can cause severe birth defects. Pregnant women should never take supplemental retinol above the RDA without medical supervision. Provitamin A carotenoids do not cause vitamin A toxicity because conversion is regulated.

Who should be cautious

Pregnant women must avoid high-dose preformed vitamin A. Heavy alcohol users have increased risk of liver toxicity. People taking retinoid medications should not supplement with vitamin A. Smokers should avoid high-dose beta-carotene supplements specifically (separate from preformed vitamin A) due to increased lung cancer risk shown in the CARET and ATBC trials.

Interactions

Orlistat reduces absorption of fat-soluble vitamin A — take them several hours apart. Mineral oil binds vitamin A and reduces absorption. Retinoid medications (like isotretinoin for acne) should never be combined with vitamin A supplements due to additive toxicity. Alcohol increases vitamin A toxicity to the liver.

Frequently asked questions

Is vitamin A safe in pregnancy?⌄

Yes at the RDA (770 mcg RAE), but high-dose preformed vitamin A (retinol) is teratogenic and can cause birth defects. Avoid supplements above the RDA and avoid liver-rich meals during pregnancy.

Should I take vitamin A or beta-carotene?⌄

Beta-carotene from food is safer because conversion is regulated. Supplemental beta-carotene at high doses should be avoided by smokers. Most multivitamins use a mix.

What are signs of vitamin A toxicity?⌄

Headache, hair loss, dry skin, bone pain, liver problems, and visual disturbances. Stop the source and consult a doctor.

Can I get enough vitamin A from a vegan diet?⌄

Through beta-carotene conversion, yes. Eat orange and dark green vegetables regularly. Cooking and pairing with fat improves absorption.

Is cod liver oil too high in vitamin A?⌄

It depends on the brand. Some traditional cod liver oils provide thousands of micrograms RAE per dose. Read labels and avoid stacking with multivitamins.

References

NIH ODS Vitamin A Fact Sheet — NIH Office of Dietary Supplements link

Track Vitamin A with Pilora

Set up dose reminders, check interactions, and join the community in the Pilora iPhone app.

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Disclaimer: These statements have not been evaluated by the FDA. This page is educational, not a substitute for personalized medical advice. Evidence grades are AI-assisted assessments — talk to your doctor before starting any new supplement, especially if you're pregnant, breastfeeding, on medications, or managing a chronic condition.