How do I convert vitamin A IU to mcg RAE?

For retinol or beta-carotene from supplements, multiply IU by 0.3. For beta-carotene from food, multiply by 0.05. So 10,000 IU of retinol equals 3,000 mcg RAE.

What is the difference between retinol and beta-carotene?

Retinol is preformed vitamin A from animal foods and supplements, and the body can use it directly. Beta-carotene is a plant pigment the body converts into vitamin A. Only preformed vitamin A has an upper limit.

Is vitamin A safe during pregnancy?

Pregnant women need some vitamin A (the RDA is 770 mcg RAE for ages 19–50), but preformed vitamin A above the upper limit can cause birth defects. Experts advise against more than 3,000 mcg RAE (10,000 IU) a day from supplements, and the NHS says to avoid liver in pregnancy.

How much vitamin A is too much?

The US upper limit for adults is 3,000 mcg a day of preformed vitamin A from food and supplements. The NHS says more than an average of 1.5 mg (1,500 mcg) a day over many years may affect bones.

What are the symptoms of too much vitamin A?

Very high single doses can cause severe headache, blurred vision, nausea, dizziness and muscle aches. Regular high intakes can cause dry skin, painful joints, fatigue and abnormal liver tests.

Should smokers avoid beta-carotene supplements?

The NHS advises people who smoke or were exposed to asbestos not to take beta-carotene supplements. In large trials, high-dose beta-carotene raised lung cancer risk in these groups.

vitamin

Vitamin A: Retinol vs Beta-Carotene, mcg RAE and IU

Also known as retinol, retinyl palmitate, retinyl acetate, beta-carotene, preformed vitamin A, provitamin A carotenoids

Short answer

Vitamin A comes in two dietary types: preformed vitamin A (retinol and retinyl esters) from animal foods and many supplements, and provitamin A such as beta-carotene from plants ^[1]. Labels use mcg RAE. The adult RDA is 900 mcg RAE for men and 700 for women ^[1]. High doses of preformed vitamin A can cause birth defects ^[1].

Last reviewed 20 October 2026 · 3 sources

What is Vitamin A?

Vitamin A is a group of fat-soluble retinoids, mainly retinol and retinyl esters ^[1]. The body uses it for vision (it is part of rhodopsin, the light-sensing protein in the retina), immune function, cell growth and differentiation, and reproduction ^[1]. The body turns provitamin A carotenoids such as beta-carotene into vitamin A, and it stores most of its vitamin A in the liver ^[1].

Forms of Vitamin A you'll see on labels

Retinyl acetate or retinyl palmitate
Preformed vitamin A, common in supplements ^[1]. Counts toward the upper limit ^[1].
Retinol
Preformed vitamin A found in animal foods ^[1]. 1 mcg retinol = 1 mcg RAE ^[1].
Beta-carotene
Provitamin A the body converts as needed ^[1]. 2 mcg from supplements = 1 mcg RAE ^[1]. It is not known to cause birth defects and has no upper limit, but large doses raised lung cancer risk in smokers ^[1].
Mixed products
Some labels say what share of the vitamin A comes from beta-carotene; only the retinol or retinyl ester share counts toward the upper limit ^[1].

How much Vitamin A do adults need?

NIH lists these Recommended Dietary Allowances (RDA) for adults 19+ in micrograms of retinol activity equivalents (mcg RAE). Reference values, not a personal recommendation.

Group	Amount per day
Men 19+	900 mcg RAE
Women 19+	700 mcg RAE
Pregnancy (19–50)	770 mcg RAE
Breastfeeding (19–50)	1,300 mcg RAE

Upper limit: 3,000 mcg/day of preformed vitamin A (retinol and retinyl esters) for adults 19+, including pregnancy and breastfeeding; food and supplements both count; there is no upper limit for beta-carotene ^[1]

How Vitamin A appears on a label

Supplement Facts labels list vitamin A in mcg RAE; older labels used IU ^[1]. 1 IU retinol = 0.3 mcg RAE, 1 IU supplemental beta-carotene = 0.3 mcg RAE, and 1 IU beta-carotene from food = 0.05 mcg RAE ^[1]. The Daily Value is 900 mcg RAE ^[1]. Stand-alone supplements often contain 3,000 mcg RAE (333% DV); multivitamins often have 750 to 1,050 mcg RAE ^[1]. If the label shows how much comes from beta-carotene, subtract that share to see the preformed amount ^[1].

When to take Vitamin A

No source we checked names a best time of day or says whether to take vitamin A with food. NIH notes that vitamin A is fat-soluble and that the body stores extra amounts, mainly in the liver ^[1].

What to keep apart from Vitamin A

Orlistat (weight-loss medicine)
It can lower absorption of vitamin A and beta-carotene; its makers advise a multivitamin with fat-soluble vitamins ^[1]. Ask your pharmacist.
Oral retinoid medicines (for example acitretin or bexarotene)
Taking them with vitamin A supplements can increase the risk of vitamin A toxicity ^[1]. Ask your pharmacist.
Liver, liver pâté and fish liver oil
These are very rich in vitamin A. The NHS says not to take vitamin A supplements, including fish liver oil, if you eat liver every week ^[2].
Smoking or asbestos exposure
Large doses of beta-carotene raised lung cancer risk in smokers and asbestos-exposed workers ^[1]. The NHS advises these groups not to take beta-carotene supplements ^[3].

Foods that contain Vitamin A

Beef liver
Oily fish such as herring and salmon
Eggs
Milk, cheese and yogurt
Fortified milk, spreads and cereals
Sweet potatoes and carrots
Spinach and other leafy greens
Pumpkin and red peppers
Cantaloupe, mango and apricots

Who should ask a doctor or pharmacist first

If you are pregnant, might be pregnant or are breastfeeding, talk to your doctor before taking vitamin A: experts advise against more than 3,000 mcg RAE (10,000 IU) a day of vitamin A supplements, and the NHS says to avoid liver and liver products in pregnancy ^[1]^[2]. Smokers, former smokers and people exposed to asbestos should ask before using beta-carotene ^[1]^[3]. Ask first if you take orlistat or a retinoid medicine ^[1]. Older adults at risk of osteoporosis should note NHS advice to keep vitamin A from food and supplements to 1.5 mg a day or less ^[2].

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Vitamin A: questions people ask

For retinol or beta-carotene from supplements, multiply IU by 0.3 ^[1]. For beta-carotene from food, multiply by 0.05 ^[1]. So 10,000 IU of retinol equals 3,000 mcg RAE ^[1].

Retinol is preformed vitamin A from animal foods and supplements, and the body can use it directly ^[1]. Beta-carotene is a plant pigment the body converts into vitamin A ^[1]. Only preformed vitamin A has an upper limit ^[1].

Pregnant women need some vitamin A (the RDA is 770 mcg RAE for ages 19–50), but preformed vitamin A above the upper limit can cause birth defects ^[1]. Experts advise against more than 3,000 mcg RAE (10,000 IU) a day from supplements, and the NHS says to avoid liver in pregnancy ^[1]^[2].

The US upper limit for adults is 3,000 mcg a day of preformed vitamin A from food and supplements ^[1]. The NHS says more than an average of 1.5 mg (1,500 mcg) a day over many years may affect bones ^[2].

Very high single doses can cause severe headache, blurred vision, nausea, dizziness and muscle aches ^[1]. Regular high intakes can cause dry skin, painful joints, fatigue and abnormal liver tests ^[1].

Yes. Long-term high beta-carotene intake can cause carotenodermia, a harmless yellow-orange skin color that goes away when intake stops ^[1].

The NHS advises people who smoke or were exposed to asbestos not to take beta-carotene supplements ^[3]. In large trials, high-dose beta-carotene raised lung cancer risk in these groups ^[1].

Stand-alone vitamin A supplements often contain 3,000 mcg RAE, and multivitamins often contain 750 to 1,050 mcg RAE ^[1].

Sources

Vitamin A and Carotenoids - Health Professional Fact Sheet — NIH Office of Dietary Supplements
Vitamins and minerals: Vitamin A — NHS
Vitamins and minerals: Others — NHS

Educational information, not medical advice. The amounts above are official reference values, not a recommendation for you. Check with your doctor or pharmacist before starting or changing supplements, especially if you take medication, are pregnant or have a health condition. Supin sells a subscription, not supplements. Last reviewed 20 October 2026.