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Supplement

Vitamin A (Retinol)

Vitamin · retinol, retinyl palmitate, retinyl acetate, retinyl esters, provitamin A, beta-carotene

Vitamin A is the vitamin for seeing in the dark, for skin, mucous membranes and immune defense. Where it is lacking, it is among the most effective measures in all of medicine. In Germany the situation is different: most people are well supplied, and for hardly any other vitamin are requirement and upper limit so close together.

In short

Vitamin A comes in two forms: as preformed retinol from animal foods and as beta-carotene from plants, which the body converts as needed. In countries with deficiency, vitamin A reduces child mortality by 12 percent, supported by data from more than one million children. In Germany, usual intake is already above the recommendations. High-dose retinol can cause birth defects during pregnancy, and beta-carotene supplements increased the risk of lung cancer in smokers. The BfR therefore proposes at most 0.2 mg of vitamin A per daily dose for food supplements, or no addition at all.

What it is

Vitamin A is fat-soluble and is stored in the liver. Preformed vitamin A, that is, retinol and its esters, is found in liver, fish, eggs and dairy products. In Germany, margarine as a butter substitute has also been fortified with vitamin A for many years. Plants supply provitamin A, mainly beta-carotene from carrots, sweet potatoes and spinach.

The D-A-CH societies recommend 0.85 mg per day for men under 65 and 0.70 mg for women, 0.80 mg for pregnant women and 1.30 mg for breastfeeding women. The calculation is in retinol activity equivalents: 12 µg of beta-carotene count as much as 1 µg of retinol. EFSA uses a ratio of 6 to 1 and arrives at 0.75 mg for men and 0.65 mg for women.

Retinol and beta-carotene are not the same

In practice, this distinction is the most important one on the entire page. Retinol acts immediately and completely, and precisely for that reason it can accumulate. The body converts beta-carotene only when it needs vitamin A. When supply is good, it slows the conversion. That is why there is no such thing as vitamin A poisoning from carrots. Anyone who eats a great deal of beta-carotene gets at most a harmless yellow-orange skin color that disappears again.

The risks differ accordingly. With retinol, the concern is birth defects in pregnancy and the liver. With beta-carotene, it is isolated, high-dose supplements in smokers. According to EFSA, beta-carotene itself is not considered harmful to the unborn child.

How well supplied we are

According to the German National Nutrition Survey, men in Germany take in a median of 1.5 to 1.8 mg of vitamin A per day and women 1.4 to 1.7 mg, calculated in retinol equivalents. That is above the recommendations. About 40 percent of respondents eat liver, and around 16 percent of people who take food supplements use a vitamin A supplement. Deficiency is therefore rare in Germany, while an excess of preformed retinol is quite possible.

How it works

In the retina, vitamin A is part of the visual pigment rhodopsin. If it is lacking, night blindness comes first. As retinoic acid, vitamin A also controls how cells in the skin and mucous membranes specialize, and it keeps the barriers and the immune system functioning. In the EU, health claims relating to vision, skin, mucous membranes, the immune system and iron metabolism are authorized.

What is well supported

In genuine deficiency, vitamin A is one of the best-supported nutrient interventions of all. According to Cochrane, the deficiency affects 190 million children under five in poorer countries. The 2022 review analyzed 47 studies with about 1.2 million children: all-cause mortality fell by 12 percent, with high certainty of evidence. Measles and night blindness also became markedly less common. The WHO therefore recommends supplementation for children aged 6 to 59 months. In measles itself, two doses on consecutive days reduced mortality in children under two. Even in rich countries there are risk groups who can develop a deficiency: premature infants and people with cystic fibrosis, Crohn’s disease or celiac disease, because they absorb fat poorly.

What the studies show

ATBC: beta-carotene in smokers

29,133 Finnish smokers aged 50 to 69 took 20 mg of beta-carotene, vitamin E, both or placebo daily for five to eight years. The aim was to prevent lung cancer. Instead, lung cancer occurred 18 percent more often under beta-carotene, and all-cause mortality was 8 percent higher.

CARET: the early stop

18,314 smokers, former smokers and asbestos workers received 30 mg of beta-carotene plus 25,000 IU of retinol or placebo daily. After a mean of 4.0 years, the risk of lung cancer was higher by a factor of 1.28 and all-cause mortality by a factor of 1.17. The study was stopped 21 months earlier than planned.

Vitamin A in pregnancy

One study followed 22,748 pregnant women. Women who took more than 10,000 IU of preformed vitamin A daily from supplements had children with malformations in tissues arising from the so-called cranial neural crest considerably more often. The ratio was 4.8 compared with women taking at most 5,000 IU. The critical period was before the 7th week of pregnancy. The authors estimated that about 1 in 57 children of these women was affected because of the supplement.

Where the data stop

For well-supplied adults there is no proven additional benefit from vitamin A or beta-carotene supplements. A Cochrane review of 78 studies found no effect on mortality for vitamin A alone, and for beta-carotene in studies with low risk of bias even a slight increase. The hope that beta-carotene protects against cancer came from observational studies with fruit and vegetables and was turned on its head in the large studies in smokers. In the eye study AREDS2, too, more lung cancer cases occurred with beta-carotene, especially in former smokers, which is why it was replaced there by lutein and zeaxanthin. For bone, the situation is open. In the Nurses’ Health Study, women with very high retinol intake had a higher risk of hip fractures, and the EU previously advised postmenopausal women to stay below 1.5 mg per day. After reviewing the newer studies, EFSA concluded in 2024 that they do not support a link with poorer bone health up to 3,000 µg. And if you are thinking of retinol for the skin: what is said about it refers to creams and retinoid medicines. For vitamin A taken by mouth, there are no robust studies on this.

Status, approval and legal

Vitamin A and beta-carotene are authorized vitamin sources for food supplements. There is not yet a binding EU maximum level. The BfR sees practically no leeway for vitamin A, because parts of the population already almost reach the upper limit through food. It therefore proposes that vitamin A in food supplements be used either not at all or at most at 0.2 mg per daily dose, with the note to take it during pregnancy only after consulting a physician. For beta-carotene, the BfR proposes at most 3.5 mg per daily dose. According to EFSA, the tolerable upper intake level for preformed vitamin A is 3,000 µg per day. Vitamin A is not on the doping list.

Safety

In pregnancy, preformed vitamin A is the critical point. The NIH advises pregnant and breastfeeding women not to take more than 3,000 µg, that is, 10,000 IU, daily as a supplement. BfR and EFSA advise pregnant women and women trying to conceive to avoid liver entirely: liver from slaughter animals contains on average 17 to 29 mg of vitamin A per 100 g. For everyone else, EFSA considers liver and offal at most once a month to be unproblematic. Smokers and former smokers should not take beta-carotene supplements. An acute overdose shows up as severe headaches, nausea, dizziness and visual disturbances, a chronic one as dry skin, joint pain, fatigue and abnormal liver values. Anyone taking retinoid medicines such as isotretinoin for acne should not take additional vitamin A supplements. The weight-loss drug orlistat, by contrast, reduces absorption.

BK-Score Well supported

Human evidence8
Mechanism9
Safety data9
Hype gap6
Track record of use10

In deficiency, vitamin A is excellently supported: the 2022 Cochrane review shows, across 19 studies with 1,202,382 children, a 12 % lower mortality (RR 0.88, high certainty). For well-supplied adults, by contrast, any additional benefit is lacking; vitamin A alone did not change mortality in 12 studies (RR 1.07, Cochrane 2012). The large prevention studies with beta-carotene harmed smokers: ATBC with 29,133 men found 18 % more lung cancer (NEJM 1994), CARET with 18,314 people at risk found RR 1.28 and was stopped 21 months early (NEJM 1996). The teratogenicity of high-dose retinol is established by Rothman 1995 (22,748 pregnant women) and is the basis of the EFSA limit of 3,000 µg per day (2024). The safety data are thus exceptionally good, and the mechanism of action in humans is known in detail. Advertising for the immune system and skin is formally covered by EU claims, but often omits that hardly anyone in Germany has a deficiency.

The score rates the state of knowledge, not the substance. “Safety data 9” means well studied – not harmless.
Subjective assessment by Biohacking Kompakt based on published scoring rules – not a scientific rating and not a medical recommendation. Rules and all ratings (German)

Frequently asked questions about vitamin A (retinol)

What is the difference between retinol and beta-carotene?

Retinol is preformed vitamin A from animal foods and acts directly. Beta-carotene comes from plants and is converted into vitamin A only as needed. That is why retinol can be overdosed, but beta-carotene from food cannot.

How much vitamin A do you need per day?

The D-A-CH societies recommend 0.85 mg per day for men under 65 and 0.70 mg for women. Most people in Germany reach this through a normal diet. According to EFSA, the upper limit for preformed vitamin A is 3,000 µg per day.

Can you take vitamin A during pregnancy?

Preformed vitamin A in high doses can cause birth defects, especially in the first weeks of pregnancy. During pregnancy, supplements should be taken only after consulting a physician. Pregnant women should avoid liver entirely; beta-carotene from vegetables is harmless.

Is beta-carotene dangerous for smokers?

In two large studies, high-dose beta-carotene supplements increased the risk of lung cancer in smokers, by 18 percent in ATBC. EFSA therefore advises smokers against beta-carotene supplements. Carrots and other vegetables are not affected.

Can you eat too much vitamin A?

With preformed vitamin A, yes, mainly through liver and supplements. Typical signs are headaches, nausea, dry skin, joint pain and elevated liver values. EFSA considers liver at most once a month to be unproblematic.

Does vitamin A help against night blindness?

Night blindness is the first sign of vitamin A deficiency, and in that case vitamin A helps. In countries with deficiency it markedly reduced its frequency in studies. In Germany, deficiency is rare, so night blindness should be evaluated by a physician.

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Information only, not medical advice and not a usage or dosage recommendation. Prescription-only and unapproved substances belong in the hands of a physician. Last updated: 2026-10-01.