Vitamins
Vitamin A
Vitamin A is an essential, fat-soluble vitamin. Your diet supplies it as preformed vitamin A or as precursors from plant foods.
Vitamin A describes a group of related substances with vitamin A activity, rather than a single molecule. Your diet supplies preformed vitamin A, mainly retinol and retinyl esters, as well as provitamin A carotenoids. These precursors include beta-carotene, alpha-carotene and beta-cryptoxanthin, which your body can convert into vitamin A. Retinol is therefore a particular form of vitamin A; beta-carotene is a precursor, not another name for the whole vitamin group.
Vitamin A: one vitamin, different forms
Vitamin A is an essential, fat-soluble vitamin. The name describes a group of related substances with vitamin A activity, rather than a single molecule. Your diet supplies two different forms: preformed vitamin A and provitamin A carotenoids, which your body can convert into vitamin A.
- Preformed vitamin A: mainly retinol and retinyl esters in animal-derived foods.
- Provitamin A carotenoids: beta-carotene, alpha-carotene and beta-cryptoxanthin from plant foods. These are precursors, not alternative names for vitamin A.
What your body needs vitamin A for
Vitamin A contributes to the maintenance of normal vision, skin and mucous membranes, as well as normal immune function and iron metabolism. It also has a role in cell specialisation—the process by which cells take on particular functions. These claims are authorised under Regulation (EU) No 432/2012; foods must meet at least the conditions for a source of vitamin A to use them. They do not mean that extra supplements improve eyesight, treat skin conditions or prevent colds when intake is already adequate.
Absorption, conversion and storage
Retinol equivalents account for the vitamin A activity of different forms. Under EFSA’s convention, 1 µg RE corresponds to either 1 µg retinol, 6 µg beta-carotene or 12 µg other provitamin A carotenoids. These factors are used for calculations: your actual absorption and conversion of beta-carotene depend on the food, your overall diet, genetic factors and health status. Conversion takes place mainly in the intestine. The liver is the main storage site for vitamin A.
The form matters when taking supplements
If you take isotretinoin, avoid additional vitamin A supplements. Discuss supplementation with your treatment team if you take other systemic retinoids or orlistat, or have chronic liver disease, renal failure or receive dialysis. These precautions are not a blanket ban on ordinary foods containing vitamin A.
How nutrition works
Vision
Skin, hair and nails
Vitamin A contributes to the maintenance of normal skin. [1]
Immune system
Vitamin A contributes to the normal function of the immune system. [1]
Statements & evidence
Vitamin A contributes to normal iron metabolism [3]
This authorised claim may only be used for foods that meet at least the conditions for a source of vitamin A. Normal iron metabolism is not the same as increased iron absorption.
Vitamin A contributes to the maintenance of normal mucous membranes [3]
The claim concerns maintaining normal mucous membranes, not treating symptoms. It may only be used for foods that meet at least the conditions for a source of vitamin A.
Vitamin A has a role in the process of cell specialisation [3]
Cell specialisation is the process by which cells take on particular functions. This is not a claim about cell division. The claim may only be used for foods that meet at least the conditions for a source of vitamin A.
Vitamin A is fat-soluble. The diet provides preformed vitamin A and provitamin A carotenoids. [4][2]
Preformed vitamin A includes mainly retinol and retinyl esters in animal-derived foods. Plant-derived foods provide provitamin A carotenoids, which your body can convert into vitamin A.
Provitamin A carotenoids are converted into retinol mainly in the intestine. The liver is the main storage site for vitamin A. [2][5]
The liver also plays a central role in retinol metabolism. Your body's ability to store vitamin A does not make high intakes harmless.
Beta-carotene absorption varies with the food, the overall diet, genetic factors and health status. [2]
Fixed conversion factors are useful for reference values, but do not precisely describe an individual's absorption and conversion.
EFSA's population reference intakes for adults are 750 µg retinol equivalents per day for men and 650 µg for women, increasing to 700 µg during pregnancy and 1,300 µg during lactation. [4]
These values concern total dietary intake and are not recommended supplement doses. Retinol equivalents (RE) account for the vitamin A activity of different forms.
Under EFSA's RE convention, 1 µg retinol equivalent corresponds to either 1 µg retinol, 6 µg beta-carotene or 12 µg other provitamin A carotenoids. [2]
These are alternative equivalent amounts, not amounts to add together. The factors are a calculation convention rather than an exact prediction of your individual conversion.
EFSA sets a tolerable upper intake level for preformed vitamin A of 3,000 µg retinol equivalents per day for adults, including during pregnancy and lactation. [5]
The upper level concerns long-term total intake from all sources, including fortified foods and supplements. It is not an intake target, does not apply to provitamin A carotenoids and should not be applied to children.
Excess preformed vitamin A can harm the development of the unborn child. [5]
EFSA advises people who are pregnant or planning pregnancy not to eat liver, offal or products made from them. This precaution concerns preformed vitamin A, not provitamin A carotenoids in the usual diet.
EFSA advises smokers to avoid beta-carotene-containing supplements because of lung-cancer risk. [5]
If you smoke, avoid these supplements. EFSA found no indication of adverse effects from beta-carotene in the background diet; ordinary foods and supplements should not be treated as equivalent here.
EFSA could not establish a tolerable upper intake level for supplemental beta-carotene. [5]
The evidence is insufficient to define a reliable dose–response relationship and derive an upper level. The absence of an upper level does not mean that unlimited amounts are safe.
EFSA could not establish a causal relationship between preformed vitamin A intakes of 1,000–3,000 µg retinol equivalents per day and increased fracture risk. [5]
Evidence for this specific relationship is insufficient. This is neither evidence of a protective effect nor proof that higher intakes are harmless.
Safety information
Side effect
Very large doses can cause acute toxicity
Very large doses of preformed vitamin A can cause severe headache, blurred vision, nausea, dizziness and impaired coordination. Severe poisoning can be life-threatening. Seek immediate medical help if a substantial overdose is suspected. These are not expected effects of meeting nutritional requirements. [7]
Upper level · Adults
Upper limit for preformed vitamin A
EFSA’s adult upper limit is 3,000 µg retinol equivalents (RE) per day of preformed vitamin A. It covers total intake from food, fortified food and supplements, including during pregnancy and breastfeeding. It is not an intake target and does not apply to beta-carotene. [5]
Upper level · Children and adolescents (1–17 years)
Children have lower upper limits
EFSA’s daily upper limits for preformed vitamin A are: 800 µg RE at ages 1–3, 1,100 at 4–6, 1,500 at 7–10, 2,000 at 11–14 and 2,600 at 15–17 years. They cover all intake sources and are not recommended amounts. Do not use high-dose products without medical guidance. [5]
Upper level
Seek professional advice on infant vitamin A supplements
For infants aged 4–11 months, EFSA’s upper limit for preformed vitamin A is 600 µg RE per day from all sources. High-dose administration can cause effects including a temporarily bulging fontanelle. Do not copy medical or public-health supplementation programmes for unsupervised home use. [5]
Caution · Pregnant women
Avoid self-prescribed retinol supplements in pregnancy
If you are pregnant or pregnancy is possible, do not take retinol supplements on your own initiative. Avoid cod-liver oil, liver and liver products. Excess preformed vitamin A can cause congenital malformations, particularly in early pregnancy. The upper limit is not permission to take a supplement up to that amount; suspected deficiency needs clinical assessment. [5][9]
Interaction
Interaction with retinoid medicines
If you take isotretinoin, avoid additional vitamin A supplements: their effects can add together and increase toxicity. With other systemic retinoids, discuss supplementation with your treatment team. This is not a blanket ban on ordinary foods containing vitamin A. [10][7]
Interaction
Orlistat can reduce absorption
Orlistat can reduce absorption of fat-soluble vitamins and beta-carotene. If a multivitamin is recommended, Xenical product information advises taking it at least two hours after orlistat or at bedtime. Do not compensate for reduced absorption with unsupervised high doses of vitamin A. [11]
Caution
Extra caution with chronic liver disease
Chronic liver disease may increase susceptibility to vitamin A toxicity. Use vitamin A supplements only after individual medical assessment and avoid intake above your requirements. [8]
Caution
Check supplements with your renal team
If you have renal failure or receive dialysis, do not take vitamin A supplements without advice from your renal team. Check multivitamins for vitamin A too. This precaution does not mean that ordinary foods must be avoided across the board. [12]
Caution
Avoid beta-carotene supplements if you smoke
If you smoke, avoid beta-carotene supplements. Trials of high-dose supplements showed increased lung cancer risk in at-risk groups; former smokers and people exposed to asbestos should also avoid using such products without professional review. These findings do not establish equivalent harm from beta-carotene in ordinary portions of vegetables. [5][7]
Upper level
No upper limit does not mean unlimited intake is safe
EFSA could establish neither an upper limit nor a safe supplemental intake level for beta-carotene. This does not demonstrate that arbitrarily high doses are safe. Limit supplementation to meeting vitamin A requirements and heed the specific risks for smokers. [5]
Side effect
High beta-carotene intake can discolour the skin
High beta-carotene intake can cause yellow-orange skin discolouration. This carotenodermia is usually harmless and reverses when intake is reduced. It is not the same as retinol poisoning. [7]
Caution
Caution with sustained high intake and bone risk
For postmenopausal women and older men, NHS guidance advises avoiding more than 1,500 µg vitamin A per day from food and supplements as a precaution. This reflects a possible association between high retinol intake and fractures. Causation is not established; this UK precaution is not EFSA’s current upper limit. [13][14]
Frequently asked questions
What does my body need vitamin A for?
Vitamin A contributes to normal vision, normal skin and normal immune function. If your intake is already adequate, this does not mean that extra supplements improve eyesight or prevent colds.
What is the difference between vitamin A, retinol and beta-carotene?
Vitamin A is an umbrella term for a group of related substances with vitamin A activity. Retinol is a form of preformed vitamin A; beta-carotene is a precursor that your body can convert into vitamin A. The two have different safety profiles.
How much vitamin A do I need each day?
EFSA’s population reference intakes for adults are 750 µg retinol equivalents (RE) per day for men and 650 µg for women. These rise to 700 µg RE during pregnancy and 1,300 µg RE during breastfeeding. The values concern total intake, not recommended supplement doses.
Can I get too much vitamin A?
Yes: preformed vitamin A can accumulate in the body, and excessive intake can cause harm, including liver damage. EFSA’s adult upper limit is 3,000 µg retinol equivalents per day from all sources; it is not an intake target. It does not apply to beta-carotene, but that does not mean high-dose beta-carotene supplements are harmless.
Can I take vitamin A during pregnancy?
You need vitamin A during pregnancy, but excess preformed vitamin A can harm the unborn child. Do not take retinol supplements without medical advice, and avoid cod-liver oil, liver and liver products. This precaution does not apply in the same way to provitamin A carotenoids in your usual diet.
More entries
Folate
Folate is a water-soluble B vitamin. Its active forms take part in DNA synthesis and amino-acid metabolism.
Vitamin B12
Vitamin B12 is an essential, water-soluble vitamin. Your body needs it for normal nervous-system function, red blood cell formation and DNA synthesis.
Vitamin C
Vitamin C is an essential, water-soluble vitamin that you need to obtain through your diet. Its principal chemical form is L-ascorbic acid.
Vitamin D
Vitamin D is a fat-soluble vitamin. The term mainly covers vitamins D₂ and D₃; your body can produce D₃ in the skin through exposure to UVB radiation.
Vitamin K
Vitamin K is an essential, fat-soluble vitamin. Your body needs it to activate proteins involved in blood clotting and bone metabolism.
Vitamin B6
Vitamin B6 is a water-soluble vitamin. Its active forms support many metabolic processes, particularly amino-acid metabolism.
Sources
- 01European Commission · 2012Commission Regulation (EU) No 432/2012 establishing a list of permitted health claims made on foods, other than those referring to the reduction of disease risk and to children's development and healthOpen source
- 02European Food Safety Authority · 2017Dietary Reference Values for nutrients: Summary reportOpen source
- 03European Commission · 2025Consolidated text of Commission Regulation (EU) No 432/2012, 20 August 2025Open source
- 04EFSA Journal · 2015Scientific Opinion on Dietary Reference Values for vitamin AEFSA Panel on Dietetic Products, Nutrition and Allergies (NDA)DOI 10.2903/j.efsa.2015.4028
- 05EFSA Journal · 2024Scientific opinion on the tolerable upper intake level for preformed vitamin A and β-caroteneDOI 10.2903/j.efsa.2024.8814
- 06European Parliament and Council of the European Union · 2011Regulation (EU) No 1169/2011 on the provision of food information to consumersOpen source
- 07National Institutes of Health, Office of Dietary SupplementsVitamin A and Carotenoids - Health Professional Fact SheetOpen source
- 08National Institutes of HealthVitamin A - LiverToxOpen source
- 09NHSPregnancy vitamins and supplementsOpen source
- 10DailyMed, U.S. National Library of MedicineDailyMed - ISOTRETINOIN capsule, liquid filledOpen source
- 11European Medicines AgencyXenical (orlistat): product informationOpen source
- 12Cambridge University Hospitals NHS Foundation TrustUsing over the counter medicines if you have renal failure or are on dialysisOpen source
- 13NHSVitamins and minerals - Vitamin AOpen source
- 14EFSA Supporting Publications · 2024Preparatory work for the update of the tolerable upper intake levels for vitamin ADOI 10.2903/sp.efsa.2024.en-8651
- 15Deutsche Gesellschaft für ErnährungAusgewählte Fragen und Antworten zu Vitamin AOpen source
- 16European Food Safety Authority · 2015Referenzwerte für die Nährstoffzufuhr: Empfehlungen zu Vitamin A veröffentlichtOpen source
- 17BMJ Open · 2024Systematic review of vitamin A supplementation — BMJ Open 2024;14:e078053Open source
- 18Cochrane Database of Systematic Reviews · 2015Vitamin A supplementation during pregnancy for maternal and newborn health outcomesOpen source
- 19Cochrane Database of Systematic Reviews · 2022Vitamin A supplementation for preventing morbidity and mortality in children from six months to five years of agePubMed 35294044Open source