< LEADERBOARD/s/vitamin-aVitamins

Vitamin A

Also sold as: Retinol · Retinyl esters · Provitamin A carotenoids

A fat-soluble vitamin required for vision, epithelial tissues and immune function. Correcting deficiency can be lifesaving, while excess preformed vitamin A and high-dose beta-carotene in smokers can cause serious harm.

Longevity

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NERD_PROTOCOL // EVIDENCE_MATRIXper goal

Research

LongevityLimited · no benefit

Longevity: No established adult life-extension benefit when vitamin A status is adequate. Child-survival benefit in deficiency-endemic settings is a separate clinical and public-health context.

REALITY CHECK // Vitamin A corrects deficiency; it does not make already adequate vision or general health continually better. The strongest survival benefit is in young children in deficiency-endemic settings. High-dose beta-carotene raised lung-cancer risk in trials, while preformed A accumulates and can damage the liver or fetus; natural origin is not a safety guarantee.

Levels: how we grade evidence. Grey = evidence of no benefit; amber = evidence it makes this goal worse.

Ratings are self-reported by a self-selected group of users: how it felt, not proof that it works.

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Check your bottle

Compare what your label says with what was used in trials. This is a trial range, not a personal prescription.

Enter the amount from your label to see the result.

How it was studied

01 // STUDIED_DOSE_RANGE

No universal adult supplement target

Medical pediatric IU regimens are not copied into consumer presets. Form and vitamin-activity units must be known.

02 // TIMING_&_MATRIX

Fat-soluble and matrix-dependent

Retinyl esters are hydrolyzed before absorption; carotenoid conversion varies. Ester mass, retinol equivalents and IU are distinct.

03 // EVALUATION_WINDOW

Deficiency and prevention contexts differ

Child-survival trials, clinical deficiency treatment and adult prevention trials address different populations and outcomes.

04 // SAFETY_&_QUALITY_GATE

3 mg/day preformed A UL

Equivalent to 3000 micrograms of preformed retinol activity from all sources. This is not a target and does not apply to beta-carotene mass.

UPPER LIMIT // The dossier reports EFSA and NIH adult ULs of 3000 micrograms/day (3 mg/day) of preformed vitamin A from all sources. This is retinol-equivalent vitamin activity, not 3 mg of arbitrary retinyl-ester powder or carotenoids. Beta-carotene has no established UL here, but high-dose supplementation is unsafe for smokers/asbestos-exposed people. Pregnancy requires specific clinical advice and avoidance of excess preformed A.

NERD'S NOTENerd Protocols · a clinical and sports dietitian based in the EU

Summary

Deficiency correction prevents or treats night blindness and xerophthalmia. In deficiency-endemic settings, a Cochrane synthesis in children aged 6-59 months reported about 12% lower all-cause mortality (RR about 0.88); this cannot be extrapolated to well-nourished adults. Beta-carotene supplement trials showed increased lung-cancer risk, especially in smokers or asbestos-exposed people. Oral supplement vitamin A is not interchangeable with prescribed acne retinoids.

Mechanism

Retinal participates in the visual cycle and retinoic-acid signaling regulates gene expression, epithelial differentiation and immunity. Preformed retinol and retinyl esters are stored in the liver. Carotenoid conversion is regulated and varies with food matrix and genetics; regulation does not make high-dose beta-carotene supplements risk-free.

Typical studied dose

No general adult wellness dose range is established in this dossier. Pediatric deficiency and measles protocols use age-specific medical regimens, sometimes expressed in IU, and are not suitable for a consumer calculator. For units only, 1000 micrograms equals 1 mg; IU conversion depends on the actual form and source. The calculator therefore disables trial-equivalence comparisons for these heterogeneous forms.

Upper limit

The dossier reports EFSA and NIH adult ULs of 3000 micrograms/day (3 mg/day) of preformed vitamin A from all sources. This is retinol-equivalent vitamin activity, not 3 mg of arbitrary retinyl-ester powder or carotenoids. Beta-carotene has no established UL here, but high-dose supplementation is unsafe for smokers/asbestos-exposed people. Pregnancy requires specific clinical advice and avoidance of excess preformed A.

POPULAR_STACKScombos with n ≥ 5

Popular stacks with Vitamin A

Not enough stack data yet. A combination with Vitamin A appears here once 5 people rate the same set.

> Rate my stack

Forms and label traps

Forms compared
Form on label	Active content	Studied range / day	Absorption & GI tolerance	Verdict
Retinyl palmitate, preformed vitamin A Best for: Clinically indicated deficiency correction after a label-unit check.	Unstandardized: active content unknown	no comparable trial range	Efficiently hydrolyzed to retinol; label activity is not raw ester mass. Physiological amounts may be tolerated; excess accumulates.	Caution [DOSSIER // CHECK_FORM] The source mixes ester mass and RAE. No assumed IU or ester-mass-to-RAE conversion is applied; use declared vitamin activity and clinician advice. PMID 23053560
Retinyl acetate, preformed vitamin A Best for: An alternative preformed label form, with the same need to verify activity units.	Unstandardized: active content unknown	no comparable trial range	High absorption; no important clinical superiority over palmitate is established. Dose-dependent accumulation and toxicity remain possible.	Caution [DOSSIER // CHECK_FORM] Do not treat mg ester compound as mg retinol activity. Trial-dose and UL comparisons are disabled without a common basis. PMID 23053560
Retinol, preformed vitamin A Best for: Identifying the preformed fraction of a label.	Unstandardized: active content unknown	no comparable trial range	Retinol mass can express retinol-equivalent activity, but no adult trial band is supplied. Excess can produce hypervitaminosis A.	Caution [DOSSIER // CHECK_FORM] No generalized wellness trial target is supplied. The 3 mg UL applies to preformed retinol activity, not a recommended intake. PMID 23053560
Beta-carotene or mixed provitamin A carotenoids Best for: Distinguishing provitamin exposure from stored preformed vitamin A.	Unstandardized: active content unknown	no comparable trial range	Conversion depends on matrix and individual genetics; dietary and oil-supplement conversion differ. Skin yellowing may occur; high-dose supplement lung-cancer risk is a separate serious harm.	Caution [DOSSIER // CHECK_FORM] Do not use a universal 12:1 or 2:1 factor for an unspecified product. No established beta-carotene UL does not mean no risk. PMID 23053560 PMID 28282870 PMID 22113863

Common label traps

TRAP_01 // VITAMIN A IMPROVES EVERYONE'S VISION
The clear benefit is correction of deficiency. Adequate adults do not gain unlimited visual performance from extra A.
TRAP_02 // BETA-CAROTENE PREVENTS CANCER
Supplement RCTs show no general cancer prevention and an increased lung-cancer risk, particularly in smokers and asbestos exposure.
TRAP_03 // AN ACNE RETINOID PROVES THE SUPPLEMENT WORKS
Topical tazarotene/tretinoin and oral isotretinoin are medicines with different evidence and supervision; their findings do not validate an oral vitamin A supplement.
TRAP_04 // A FAT-SOLUBLE VITAMIN CANNOT BE OVERDOSED
Preformed A is stored in the liver and can cause chronic liver, bone and pregnancy-related harm.
TRAP_05 // ESTER MG, RAE AND IU ARE INTERCHANGEABLE
Vitamin activity and raw compound mass differ. Form-specific information is essential before conversion.

Other outcomes studied

Outside the five leaderboard goals. Same evidence levels as above.

DEFICIENCY-RELATED EYE DISEASE Strong · benefit
Strong clinical and public-health evidence concerns vitamin A deficiency, night blindness and xerophthalmia; it is not evidence for enhanced vision in replete adults.
PMID 35294044 PMID 21868478 PMID 39694460
CHILD SURVIVAL IN DEFICIENCY SETTINGS Strong · benefit
Children aged 6-59 months in deficiency-endemic settings: about 12% lower all-cause mortality in the cited Cochrane synthesis. Do not extrapolate to replete adults.
PMID 35294044 PMID 21868478 PMID 8426449
MEASLES TREATMENT IN CHILDREN Limited · benefit
The older Cochrane synthesis found benefit in a two-dose regimen in children under two (mortality RR 0.18, CI 0.03-0.61); pooled all-age or single-dose findings were not significant. This belongs in age-specific medical care.
PMID 16235283
ANEMIA WITH COEXISTING DEFICIENCY Limited · benefit
A clinical synthesis reported about 26% lower anemia risk, but no significant change in iron-deficiency frequency in children/adolescents (RR 0.82, CI 0.60-1.12). This is not universal iron-deficiency treatment.
PMID 29336593
BETA-CAROTENE LUNG-CANCER HARM Limited · makes it worse
Eight RCTs with 167141 participants: lung-cancer RR 1.16 (95% CI 1.06-1.26); smokers/asbestos-exposed subgroup RR 1.21 (1.08-1.35). This is supplement-trial harm, not a reason to avoid vegetables.
PMID 35405977 PMID 36715090 PMID 19876916 PMID 18429004
GENERAL CANCER PREVENTION Limited · no benefit
Randomized supplement syntheses do not support beta-carotene as a general cancer-prevention tool; some outcomes suggest harm.
PMID 21981610 PMID 18173999
AMD COMBINATION FORMULAS Limited · benefit
Benefits of multi-ingredient antioxidant/mineral regimens cannot be assigned to vitamin A alone. Later formulations replace beta-carotene because of lung-cancer concerns.
PMID 18425071
FRACTURE ASSOCIATIONS Limited · makes it worse
Prospective cohorts link higher retinol intake with some fracture risks, while beta-carotene associations differ. These are observational associations, not proof of causality.
PMID 32871858 PMID 33129293
ORAL SUPPLEMENT FOR ACNE No established evidence
The supplied topical-retinoid papers evaluate medicines and do not establish efficacy of oral vitamin A supplements at safe doses.
PMID 15543714 PMID 21550137
REPLENISHED ADULT PREVENTION Limited · no benefit
A large synthesis of primary/secondary prevention trials did not establish clear clinically important benefit for people without deficiency; certainty and population differences matter.
PMID 38816049

Reader questions

Retinol or beta-carotene?

Preformed retinol directly raises vitamin A exposure but accumulates. Carotenoid conversion varies with genetics and matrix. The latter is not a reliable reason to take high-dose beta-carotene, especially if smoking or asbestos exposure applies.

Can I take it for acne or better vision?

Deficiency-related vision problems need assessment; extra A is not proven to improve adequate vision. Acne-retinoid medicine evidence does not establish supplement efficacy.

Is it safe in pregnancy?

Excess preformed vitamin A can cause birth defects. Review prenatal products, diet and medicines with a clinician; do not start a high-dose product on your own.

How do I read micrograms, milligrams and IU?

1000 micrograms equals 1 mg, but that unit conversion does not resolve whether the label means retinol activity, retinyl-ester mass or carotenoid mass. No universal IU conversion is used here.

Stack interactions

Danger Systemic retinoids [CAUTION // REVIEW_WITH_CLINICIAN]
Potential additive retinoid toxicity, liver injury, mucosal effects and intracranial-pressure concerns. Do not add supplemental vitamin A without the prescriber.
PMID 2103414
Danger Alcohol and liver-toxic exposures [CAUTION // REVIEW_WITH_CLINICIAN]
The dossier identifies overlapping liver risks. One cited alcohol interaction study is in rats, so it cannot quantify a human interaction magnitude.
PMID 6353294 PMID 16448456
Caution Tetracycline antibiotics [CAUTION // REVIEW_WITH_CLINICIAN]
The dossier flags high vitamin A/retinoid exposure as an intracranial-hypertension concern. No individually indexed interaction paper is supplied; seek medicine-specific review.
Caution Orlistat, mineral oil and bile-acid sequestrants [CAUTION // REVIEW_WITH_CLINICIAN]
Reduced fat-soluble vitamin absorption is a source-dossier pharmacology precaution without a paper-specific reference here; discuss monitoring if clinically relevant.
Caution Vitamin D, E, zinc, iron and K [CAUTION // REVIEW_WITH_CLINICIAN]
These nutrients interact with vitamin A metabolism or transport, but mechanisms do not justify an automatic high-dose stack. Zinc supports retinol transport, and coexisting deficiencies require individual assessment.

Red flags: interactions and who should avoid it

Interactions

Systemic retinoids such as isotretinoin or acitretin can add retinoid toxicity; do not add vitamin A supplements without the treating clinician. Tetracyclines plus high retinoid exposure can raise concern for intracranial hypertension; this interaction lacks an individually indexed supporting paper in the supplied dossier. Alcohol and liver-toxic exposures add concern. Orlistat, mineral oil and bile-acid sequestrants may reduce fat-soluble vitamin absorption; the source has no paper-specific citation for that point.

Avoid or ask a doctor first if

Pregnancy or pregnancy planning: excess preformed vitamin A can cause birth defects; seek prenatal clinical advice rather than self-selecting high doses. Avoid high-dose beta-carotene with smoking or asbestos exposure. Liver disease, heavy alcohol use, systemic retinoid treatment and osteoporosis risk warrant review. Headache with visual changes, persistent nausea, peeling skin, hair loss, bone pain or suspected liver injury may signal toxicity and need medical assessment.

Sources (PubMed, 24)

Vitamin A supplementation for preventing morbidity and mortality in children from six months to five years of age.
PMID 35294044 · 2022 · systematic review and meta-analysis
Deficiency-endemic child morbidity and survival evidence, not adult wellness enhancement.
Vitamin A supplements for preventing mortality, illness, and blindness in children aged under 5: systematic review and meta-analysis.
PMID 21868478 · 2011 · systematic review and meta-analysis
Child deficiency, blindness and mortality synthesis.
Prevalence of ocular manifestations of vitamin A deficiency in children: A systematic review.
PMID 39694460 · 2025 · systematic review and meta-analysis
Ocular manifestations of deficiency in children; not proof of enhanced vision in replete adults.
Vitamin A supplementation and child mortality. A meta-analysis.
PMID 8426449 · 1993 · systematic review and meta-analysis
Earlier child-mortality intervention synthesis.
Vitamin A for treating measles in children.
PMID 16235283 · 2005 · systematic review and meta-analysis
Measles-treatment evidence with age- and regimen-specific effects.
Effect of vitamin A supplementation on iron status in humans: A systematic review and meta-analysis.
PMID 29336593 · 2019 · systematic review and meta-analysis
Iron-status and anemia outcomes, with limits on iron-deficiency correction.
Role of Beta-Carotene in Lung Cancer Primary Chemoprevention: A Systematic Review with Meta-Analysis and Meta-Regression.
PMID 35405977 · 2022 · systematic review and meta-analysis
Randomized beta-carotene lung-cancer harm, particularly smoking/asbestos subgroups.
Association between β-carotene supplementation and risk of cancer: a meta-analysis of randomized controlled trials.
PMID 36715090 · 2023 · systematic review and meta-analysis
Randomized beta-carotene cancer-risk synthesis.
Beta-carotene supplementation and cancer risk: a systematic review and metaanalysis of randomized controlled trials.
PMID 19876916 · 2010 · systematic review and meta-analysis
No general cancer-prevention justification and potential harm with beta-carotene.
Beta-carotene in multivitamins and the possible risk of lung cancer among smokers versus former smokers: a meta-analysis and evaluation of national brands.
PMID 18429004 · 2008 · systematic review and meta-analysis
Lung-cancer-risk context in smokers and former smokers.
Effects of beta-carotene supplements on cancer prevention: meta-analysis of randomized controlled trials.
PMID 21981610 · 2011 · systematic review and meta-analysis
No established general cancer-prevention benefit of beta-carotene supplements.
Efficacy of antioxidant supplementation in reducing primary cancer incidence and mortality: systematic review and meta-analysis.
PMID 18173999 · 2008 · systematic review and meta-analysis
Broad antioxidant-supplement cancer incidence/mortality context; not vitamin-A-specific efficacy.
Antioxidant supplements to prevent or slow down the progression of AMD: a systematic review and meta-analysis.
PMID 18425071 · 2008 · systematic review and meta-analysis
Combination antioxidant formulas in AMD; cannot assign benefit to vitamin A alone.
Dietary vitamin A, C, and E intake and subsequent fracture risk at various sites: A meta-analysis of prospective cohort studies.
PMID 32871858 · 2020 · systematic review and meta-analysis
Observational vitamin-intake and fracture associations.
Effects of β-carotene intake on the risk of fracture: a Bayesian meta-analysis.
PMID 33129293 · 2020 · systematic review and meta-analysis
Different observational fracture pattern for beta-carotene.
Meta-analysis of topical tazarotene in the treatment of mild to moderate acne.
PMID 15543714 · 2004 · systematic review and meta-analysis
Topical tazarotene medicine evidence, explicitly not oral supplement evidence.
Use of topical tretinoin and the development of noncutaneous adverse events: evidence from a systematic review of the literature.
PMID 21550137 · 2011 · systematic review and meta-analysis
Topical tretinoin medicine safety evidence, explicitly not oral supplement efficacy.
Effects of primary or secondary prevention with vitamin A supplementation on clinically important outcomes: a systematic review of randomised clinical trials with meta-analysis and trial sequential analysis.
PMID 38816049 · 2024 · systematic review and meta-analysis
Large prevention synthesis with low-certainty and population-dependent benefit.
The challenge to reach nutritional adequacy for vitamin A: β-carotene bioavailability and conversion--evidence in humans.
PMID 23053560 · 2012 · narrative review
Human carotenoid bioavailability and conversion; activity units differ from compound mass.
Genetic Variations Associated with Vitamin A Status and Vitamin A Bioavailability.
PMID 28282870 · 2017 · narrative review
Genetic variation and vitamin A conversion/status.
Single nucleotide polymorphisms upstream from the β-carotene 15,15'-monoxygenase gene influence provitamin A conversion efficiency in female volunteers.
PMID 22113863 · 2012 · observational study
Volunteer genetic-association data on variable carotenoid conversion.
Hepatic toxicity of vitamin A and synthetic retinoids.
PMID 2103414 · 1990 · narrative review
Preformed vitamin A and systemic-retinoid liver toxicity review.
Hypervitaminosis A enhances hepatotoxicity of ethanol in rats.
PMID 6353294 · 1983 · study type unspecified in dossier
Rat alcohol-hypervitaminosis A interaction; explicitly preclinical.
Hypervitaminosis A-induced liver fibrosis: stellate cell activation and daily dose consumption.
PMID 16448456 · 2006 · observational study
Hypervitaminosis-related liver fibrosis and exposure safety context.

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