Vitamin A (retinol and provitamin-A carotenoids)

Vitamin A is a fat-soluble vitamin that exists in two main forms — preformed retinol (retinyl esters from animal-source food and supplements) and provitamin-A carotenoids (beta-carotene, alpha-carotene, beta-cryptoxanthin from orange/red/dark-green plant foods). The body converts carotenoids to retinol on demand. UK adult NRV is 800 µg retinol equivalents (RE)/day. EFSA-authorised UK health claims at ≥15 % NRV (≥120 µg RE) include contributions to normal skin, vision, and immune-system function. Two safety stories shape responsible vitamin-A supplementation: (1) preformed retinol is teratogenic — pregnant women should NOT take retinyl-palmitate-style supplements above NRV, only carotenoids; (2) high-dose beta-carotene supplements increased lung cancer in smokers and asbestos workers in the ATBC and CARET trials.

Camden Medicals editorial · Last reviewed 12 June 2026 · Next review June 2027

  • Cross-checked against
  • NHS
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  • EFSA
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Verifera Evidence ReviewCamden evidence review · independently appraised — graded, not guessed.

Camden's editorial team independently graded each health claim below on the strength of the published evidence — see the grade beside every condition.

Class
Vitamin
Typical daily dose
Most adults: dietary intake meets NRV. Multivitamin top-up at 50-100 % NRV (400-800 µg) is appropriate. Health-claim threshold: 120 µg RE (15 % NRV) per portion.
Top use evidence
Strong
On this page
  1. What it is
  2. How it works

What it is

Vitamin A is the family name for several fat-soluble compounds with retinol-like biological activity. Two distinct forms enter the diet:

Preformed retinol (and its ester forms retinyl palmitate and retinyl acetate) comes from animal-source foods — liver and liver products are by far the most concentrated source, followed by oily fish, butter, whole milk, cheese, and eggs. Cod liver oil is a long-traditional Western source. Preformed retinol is absorbed efficiently and is the form that creates teratogenic risk at supratherapeutic intake.

Provitamin-A carotenoids — predominantly beta-carotene, with smaller contributions from alpha-carotene and beta-cryptoxanthin — come from orange, red, and dark-green plant foods (carrots, sweet potato, butternut squash, spinach, kale, mango, papaya). The body converts these to retinol on demand; conversion is regulated, so high carotenoid intake from food does NOT cause vitamin A toxicity. The pigment can deposit in skin, harmlessly turning palms and soles orange (carotenodermia), but this is cosmetic and reversible.

UK supplements typically use either retinyl palmitate (synthetic retinol ester), beta-carotene, or a combination. Multivitamin formulations for general adult use commonly provide 50-100 % NRV from a mix of retinyl palmitate plus beta-carotene; pregnancy multivitamins use beta-carotene only and either omit retinol entirely or keep it well below the 1.5 mg/day pregnancy ceiling. UK regulatory NRV is expressed in retinol equivalents (RE), which already corrects for conversion efficiency.

At a glance

  • UK nutrient reference value (NRV) = 800 µg retinol equivalents (RE) per day. Most UK adults reach it through diet — liver, dairy, eggs and oily fish for retinol; carrots, sweet potato and dark leafy greens for carotenoids.
  • PREGNANCY: avoid liver and liver products, and avoid supplements containing preformed retinol (retinyl palmitate, retinyl acetate, fish-liver oils) unless prescribed — preformed retinol is teratogenic at high doses. Beta-carotene from food is not restricted; the body converts only what it needs.
  • SMOKERS, ex-smokers and people with asbestos exposure: avoid high-dose beta-carotene supplements (20–30 mg/day). The ATBC (1994) and CARET (1996) trials both found higher lung-cancer incidence in these groups. Carotenoids from food are not implicated.
  • GB-authorised health claims for vitamin A include its contribution to the maintenance of normal skin, the maintenance of normal vision, and the normal function of the immune system — usable only at ≥15 % NRV (120 µg RE) per portion.

What people use it for

  • Adults with a varied UK diet

    Most adults reach the 800 µg RE NRV through normal eating — liver/eggs/dairy contribute preformed retinol; orange/red/dark-green vegetables contribute carotenoids. A multivitamin providing 50-100 % NRV is unproblematic for non-pregnant adults; high-dose preformed-retinol supplementation is not warranted. [3]

    Popular, not provenInsufficient

  • Vegans and vegetarians (no liver, fish, eggs, or dairy)

    Plant-based diets supply provitamin-A as carotenoids only. Conversion to retinol is regulated and efficient in most adults; intake of orange/red/dark-green vegetables generally meets NRV. Pregnant or breastfeeding vegans should follow specific guidance on intake variety and consider a vegan pregnancy multivitamin formulated with beta-carotene. [1]

    Some evidenceLimited

  • Pregnant women considering a multivitamin

    AVOID supplements containing preformed retinol (retinyl palmitate / retinyl acetate) unless prescribed. UK Department of Health advice is no liver, no cod liver oil, no high-dose vitamin A in pregnancy. Beta-carotene from food and from pregnancy multivitamins is safe — the body regulates conversion. Folic acid + vitamin D are the two prescriptive supplements; vitamin A from carotenoid sources is dietary. [2,6]

    Some evidenceStrong

  • Current smokers, ex-smokers, and people exposed to asbestos

    AVOID high-dose beta-carotene supplements (≥20 mg/day). The ATBC (1994, 20 mg/day) and CARET (1996, 30 mg/day) trials both found increased lung-cancer incidence and mortality with beta-carotene supplementation in these populations. Carotenoids from food are not implicated; the harm signal is specifically with high-dose isolated supplements. [7,8]

    Some evidenceStrong

  • People in low-income / vitamin-A-deficient settings (developing-country relevance)

    In countries where vitamin A deficiency is endemic, WHO supplementation programmes reduce child mortality and night-blindness substantially. In the UK, frank vitamin A deficiency is rare and is usually secondary to fat-malabsorption (cystic fibrosis, cholestatic liver disease) — a specialist-supervised context, not self-supplementation. [9]

    Some evidenceStrong

How it works

Retinol is converted in target tissues to retinal (the visual pigment chromophore in rhodopsin, hence "vision") and to retinoic acid (a nuclear receptor ligand for RAR and RXR transcription factors that regulate cell differentiation, immune-cell function, and epithelial maintenance — hence "skin", "immune system", and "cell specialisation" claims).

Common myths

Myth""Vitamin A is good for the eyes — more is better.""

RealityVitamin A is essential for retinal function and the body uses it precisely. Beyond meeting the NRV, additional vitamin A does NOT improve vision in healthy people. Overdose causes acute and chronic toxicity. The NRV-tier dose is the right dose for general use. [1]

Myth""Beta-carotene is just safer vitamin A.""

RealityFor pregnancy and general food intake — yes, beta-carotene from food is regulated by the body and not teratogenic. For SMOKERS — no, high-dose beta-carotene supplements have a clear harm signal in two large RCTs (ATBC, CARET) showing increased lung-cancer risk. Carotenoids from food are not implicated; the signal is specifically with isolated high-dose supplements. [7,8]

Myth""I should take a vitamin A supplement during pregnancy.""

RealityNo. UK guidance specifically WARNS against vitamin A supplements in pregnancy because preformed retinol is teratogenic at high doses. Pregnancy multivitamins use beta-carotene only and keep total vitamin A well below the 1.5 mg/day pregnancy ceiling. Folic acid (400 µg) + vitamin D (10 µg) are the two NHS-recommended pregnancy supplements — not vitamin A. [2,6]

Myth""Carotenodermia (orange skin) means vitamin A toxicity.""

RealityCarotenodermia is a harmless cosmetic effect of high carotenoid intake from food (carrots, sweet potato, juicing). It is NOT vitamin A toxicity — the body does not overconvert carotenoids to retinol. The orange tint resolves over weeks once intake reduces.

Common online questions

Synthesised from the questions UK shoppers most often ask online about Vitamin A (retinol and provitamin-A carotenoids). Each answer is editorial and links to its evidence in the Sources list below.

How much vitamin A do I need?

UK NRV is 800 µg retinol equivalents per day for adults. Most people reach this through normal eating. A multivitamin providing 50-100 % NRV is unproblematic for non-pregnant adults. High-dose preformed-retinol supplements are NOT recommended outside specific medical contexts. [1]

I'm pregnant — can I take a vitamin A supplement?

No, not unless your GP or midwife prescribes one. UK Department of Health guidance is to avoid liver and cod liver oil throughout pregnancy and to avoid supplements containing preformed retinol (retinyl palmitate, retinyl acetate). Beta-carotene from a pregnancy multivitamin is safe. Folic acid (400 µg) and vitamin D (10 µg) are the two NHS-recommended pregnancy supplements. [2,6]

I''m a smoker — should I take beta-carotene?

No. The CARET (1996) and ATBC (1994) trials both found that high-dose beta-carotene supplements (20-30 mg/day) INCREASED lung-cancer risk in smokers and asbestos-exposed workers. The harm signal is specific to high-dose isolated supplements; carotenoids from food are not implicated. If you smoke or have smoked recently, avoid high-dose beta-carotene supplements. [8,7]

My skin is orange after eating lots of carrots — is that vitamin A toxicity?

No. Carotenodermia (the orange tint of palms and soles after high carotenoid intake) is a harmless cosmetic effect — the body regulates conversion of carotenoids to retinol, so high carotenoid intake does NOT cause true vitamin A toxicity. The colour fades over weeks as intake reduces. Vitamin A toxicity from food is essentially limited to liver consumption (or cod liver oil).

⚖️ The official position

What may lawfully be claimed about Vitamin A (retinol and provitamin-A carotenoids) in Great Britain. This is a regulatory position, not an evidence grade.

A health claim is authorised in Great Britain.

“Vitamin A contributes to the maintenance of normal skin”

“Vitamin A contributes to the maintenance of normal vision”

“Vitamin A contributes to the normal function of the immune system”

“Vitamin A contributes to normal iron metabolism”

“Vitamin A contributes to the maintenance of normal mucous membranes”

“Vitamin A has a role in the process of cell specialisation”

This claim is authorised for use in Great Britain under the GB Nutrition and Health Claims regulation. A product may carry it when it provides at least 15% of the UK NRV per recommended daily portion.

Authorised UK health claims

Verbatim from the GB Nutrition and Health Claims Register (Reg 432/2012 as assimilated in GB). A product can carry these claims when it provides at least 15% of the UK NRV per recommended daily portion.

6 authorised claims — show / hide
  • "Vitamin A contributes to the maintenance of normal skin"
  • "Vitamin A contributes to the maintenance of normal vision"
  • "Vitamin A contributes to the normal function of the immune system"
  • "Vitamin A contributes to normal iron metabolism"
  • "Vitamin A contributes to the maintenance of normal mucous membranes"
  • "Vitamin A has a role in the process of cell specialisation"

🔬 Camden’s evidence review

The research Camden reviewed, graded on its strength. This is our own appraisal — it sits beneath the official guidance above, never above it.

  1. Maintenance of normal skin, vision, and immune function

    StrongEvidencestrong

    Vitamin A's role in retinal photoreceptor function, epithelial maintenance, and adaptive-immune development is established cell biology. UK-authorised health claims sit at ≥15 % NRV (≥120 µg RE per portion) under assimilated Regulation (EU) 432/2012, and include the maintenance of normal skin, the maintenance of normal vision, and the normal function of the immune system. [3]

  2. Lung-cancer incidence in smokers (high-dose beta-carotene supplementation)

    StrongEvidencestrong

    CARET (Omenn 1996, n = 18,314 smokers/ex-smokers/asbestos-exposed workers) randomised participants to 30 mg beta-carotene + 25,000 IU retinol daily versus placebo. The trial was STOPPED EARLY at mean 4 years follow-up because the active arm had higher lung-cancer incidence (RR 1.28, 95 % CI 1.04-1.57, P = .02) and higher all-cause and lung-cancer mortality. ATBC (Heinonen 1994, n = 29,133 male Finnish smokers) randomised to 20 mg/day beta-carotene also found higher lung-cancer incidence (+18 %, 95 % CI 3-36 %) and higher overall mortality. The honest interpretation: high-dose beta-carotene supplements are CONTRAINDICATED in smokers and asbestos-exposed workers. [8,7]

  3. Teratogenicity of high-dose preformed retinol in pregnancy

    StrongEvidencestrong

    Rothman 1995 (NEJM, n = 22,748 pregnant women) found that preformed vitamin A supplementation above 10,000 IU/day in early pregnancy was associated with a 3-5-fold increased risk of cranial-neural-crest birth defects. The estimated absolute risk: about 1 in 57 babies born to mothers taking >10,000 IU/day had a malformation attributable to vitamin A. UK guidance accordingly: no preformed-retinol supplementation in pregnancy unless prescribed; avoid liver and cod liver oil throughout pregnancy. [6,10]

  4. Bone-fracture risk at high vitamin A intake (observational)

    LimitedEvidencelimited

    Observational evidence links high preformed-retinol exposure with fracture risk — notably Michaëlsson 2003 (NEJM), a Swedish cohort in which higher serum retinol was associated with increased fracture risk in men; intake-based cohort studies have reported similar signals in postmenopausal women. The signal is observational and the dose-response not fully resolved; UK guidance reflects this by capping vitamin A from food + supplements at 1500 µg/day in older adults and women near menopause. [1]

  5. Vitamin A deficiency (low-income / fat-malabsorption populations)

    StrongEvidencestrong

    In settings where vitamin A deficiency is endemic, WHO-supervised supplementation reduces child mortality and night-blindness substantially (Cochrane review CD008524). In the UK, vitamin A deficiency is uncommon and is usually secondary to fat-malabsorption disorders (cystic fibrosis, cholestasis, abetalipoproteinaemia) — a specialist-supervised therapeutic context. [9]

Safety

NRV-tier vitamin A from food or a multivitamin is well-tolerated and beneficial as part of normal nutrition. Two specific harms to know about — preformed retinol is teratogenic in pregnancy (avoid retinyl-palmitate supplements and liver in pregnancy) and high-dose beta-carotene supplements increased lung cancer in smokers in two large RCTs.

Talk to your pharmacist or GP first if you:

  • You are pregnant, planning pregnancy, or breastfeeding — avoid preformed-retinol supplements unless prescribed; choose pregnancy multivitamins formulated with beta-carotene only.
  • You smoke or have smoked recently, or have asbestos exposure history — avoid high-dose beta-carotene supplements.
  • You take oral retinoid medication (isotretinoin, acitretin, alitretinoin) — additive vitamin A toxicity risk; do not co-supplement.
  • You have liver disease — vitamin A is hepatically metabolised; chronic high intake can cause liver toxicity.
  • You have fat-malabsorption (cystic fibrosis, cholestasis, abetalipoproteinaemia) — your specialist team should set vitamin A dose; do not self-supplement.
  • You take warfarin and consume liver or cod liver oil regularly — vitamin K content in liver may affect INR.

Common side effects: At NRV-tier intake from food or multivitamin: well-tolerated. At high preformed-retinol doses: nausea, headache, hair loss, dry skin, bone tenderness; chronic high intake causes liver damage. At high beta-carotene intake: harmless skin pigmentation (carotenodermia).

Pregnancy and breastfeeding

Preformed-retinol supplements (retinyl palmitate, retinyl acetate, cod liver oil) are contraindicated in pregnancy unless prescribed — preformed retinol is teratogenic at high doses (Rothman 1995). Pregnancy multivitamins use beta-carotene only. UK guidance: avoid liver and liver products throughout pregnancy.

NRV-tier vitamin A intake during breastfeeding is appropriate. The UK reference intake is higher during lactation — the COMA Reference Nutrient Intake rises to about 950 µg/day for breastfeeding women (the 600 µg/day base plus a 350 µg lactation increment) to support infant intake via breast milk. Avoid high-dose preformed-retinol supplements.

Talk to your GP, midwife, or pharmacist before starting any supplement during pregnancy or breastfeeding.

More clinical detail (for clinicians and informed readers)

Contraindications

  • Pregnancy and women planning pregnancy — preformed-retinol supplements contraindicated unless prescribed.
  • Concurrent oral retinoid therapy (isotretinoin, acitretin) — additive toxicity.
  • Active liver disease — relative contraindication to high-dose vitamin A.
  • Smokers and asbestos-exposed workers — high-dose beta-carotene supplements contraindicated.

Drug interactions

  • Oral retinoids (isotretinoin, acitretin, alitretinoin, bexarotene) — additive vitamin A toxicity; do NOT co-supplement.
  • Warfarin — large preformed-retinol doses may alter vitamin K-dependent clotting (theoretical); routine multivitamin doses unproblematic.
  • Tetracycline antibiotics — co-administration can rarely raise intracranial pressure (idiopathic intracranial hypertension association).
  • Cholestyramine, orlistat, mineral oil — reduce fat-soluble vitamin absorption; spaced dosing or supervised supplementation may be needed.
  • Hepatotoxic drugs (e.g. methotrexate) — additive liver toxicity at high vitamin A intake.

This is not an exhaustive list. Always tell your prescriber and pharmacist about every supplement you take.

Common side effects

  • well-tolerated.
  • harmless skin yellow-orange pigmentation (carotenodermia), reversible.

Rare side effects

  • nausea, vomiting, severe headache, blurred vision, dizziness.
  • hair loss, dry/peeling skin, bone pain and fractures, liver damage, raised intracranial pressure (especially in children).
  • Birth defects (preformed retinol >10,000 IU/day in early pregnancy).

How to take it

Typical supplemental range
Most adults: dietary intake meets NRV. Multivitamin top-up at 50-100 % NRV (400-800 µg) is appropriate. Health-claim threshold: 120 µg RE (15 % NRV) per portion.
Timing
With a meal containing fat, for absorption.

How to spot quality

Look for

  • Form named explicitly: "retinyl palmitate" / "retinyl acetate" (preformed retinol) or "beta-carotene" (provitamin-A carotenoid). Multi-vitamins ideally declare both contributions.
  • Dose declared in µg RE (retinol equivalents) with NRV % stated.
  • Pregnancy formulations: beta-carotene-only OR clearly state "no preformed retinol".
  • Smoker-targeted formulations: explicit absence of beta-carotene OR a smoker-warning declaration if it is included.
  • GMP-certified manufacture; capsule shell declared (gelatin vs vegan-cellulose).

Red flags

  • Preformed-retinol products marketed for pregnancy without a clear retinol-warning — UK Department of Health guidance is the opposite.
  • High-dose beta-carotene products marketed for general "antioxidant" or "wellness" benefit without a smoker-warning — ATBC and CARET data are explicit about harm in smokers.
  • "Boosts immunity" wording — vitamin A has an EFSA-authorised "normal function of the immune system" claim, but "boosts" is not authorised wording.
  • Doses that exceed 1500 µg RE/day in formulations targeted at older adults or postmenopausal women — bone-fracture observational signal.
  • "Acne medicine" / "psoriasis remedy" wording — pharmaceutical retinoids (isotretinoin, acitretin) are licensed for those conditions, not food-supplement vitamin A. Conflating the two is misleading.

Commonly combined with

Other ingredients that share a biological pathway, cofactor relationship, or evidence-backed protocol with this one. Mechanisms below cite primary physiology — not folk pairing. Doses are literature ranges, not recommendations. Talk to your pharmacist or GP before changing your stack, especially if you take prescription medication.

Retinol (Vitamin A1, all-trans-retinol)

Insufficient evidence

Topical retinoid family — oral upstream nutrient + topical cosmetic actives.

Oral vitamin A (retinol palmitate / acetate) delivers systemic vitamin-A status; topical retinol delivers localised retinoid signalling. Different contexts; same vitamer family. Camden retinol covers topical.

Evidence: Camden retinol + retinal + isotretinoin topical retinoid cluster.

Doses studied: Oral 800 µg / day NRV. Topical retinol 0.2-0.5%.

Vitamin E (alpha-tocopherol)

Moderate evidence

Fat-soluble vitamin antioxidant cluster.

Vitamin A + vitamin E both fat-soluble lipid-membrane stability. UK Article 13.1 cell-protection claim for vitamin E.

Evidence: UK Article 13.1 vitamin E claim authorised. [3]

Doses studied: 800 µg vitamin A + 12 mg vitamin E daily (often co-formulated).

Vitamin D3

Moderate evidence

Fat-soluble vitamin cluster — A + D + E + K all fat-soluble; co-formulated.

All four fat-soluble vitamins; commonly co-formulated. Different mechanisms / claims.

Evidence: UK Article 13.1 immune / bone / muscle claims for vitamin D. [3]

Doses studied: 800 µg vitamin A + 10-25 µg vitamin D3 daily.

Related ingredients

Verifera™ is published by Camden Medicals — a UK supplement retailer. We have a commercial interest in some of the ingredients described here; we declare it on every page and our editorial process forbids adjusting copy to favour our own products. Read our editorial policy.

This page is information, not medical advice. Talk to your pharmacist or GP before starting any supplement, especially if you take prescribed medicines, are pregnant or breastfeeding, or have an existing condition.

Suspected side effects can be reported to the MHRA via the Yellow Card scheme: yellowcard.mhra.gov.uk