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evidence · mechanism · dose
Supplements/Vitamin

Vitamin A (Retinol)

aka Retinol · Retinyl Palmitate

Fat-soluble vitamin essential for vision, immune function, and epithelial integrity.

Eye HealthImmune FunctionSkin, Hair & NailsGeneral Wellness

Overview

Fat-soluble vitamin essential for vision, immune function, and epithelial integrity.

Natural sources
  • Liver
  • Egg yolk
  • Butter
  • Cod liver oil
Common forms
  • Retinol
  • Retinyl palmitate
  • Beta-carotene (provitamin)

Mechanism of action

Binds retinoic acid receptors (RAR/RXR) regulating gene transcription; rhodopsin precursor in retina.

Pathways
  • · RAR/RXR signaling
  • · Visual cycle

Effects on the body

Supports
Night vision
Supports
Mucosal immunity

Organ system effects

Eye

Rhodopsin component for low-light vision.

Immune System

Maintains mucosal barriers and T-cell function.

Evidence-based benefits

Prevents xerophthalmia / night blindness

Strong evidence

Reduces measles mortality in deficient children

Strong evidence

Potential side effects

Common
    Rare
    • · Headache
    • · Dry skin
    Serious
    • · Hepatotoxicity & birth defects at >10,000 IU/d chronically

    Drug interactions

    Isotretinoin / Acitretin
    Additive vitamin A toxicity.
    severe
    Warfarin
    May potentiate at high doses.
    moderate

    Safety & non-supplemental interactions

    Educational summary — always confirm with your clinician or pharmacist before starting, stopping, or combining with prescription therapy.

    Avoid if you are
    • ·Pregnant — teratogenic above 10,000 IU/day (retinol forms)
    Avoid with these conditions
    • ·Autoimmune disease (theoretical immune activation)
    • ·Liver disease
    • ·High alcohol intake (additive hepatotoxicity)
    Avoid / monitor with these medications
    • ·Immunosuppressants
    • ·Acitretin, isotretinoin, other retinoids (additive toxicity)
    • ·Tetracyclines (intracranial pressure)
    • ·Anticoagulants (high dose)

    Supplement interactions

    Pairs well with

    None listed.

    Avoid combining with
    • Pregnancy (high-dose retinol)
      Teratogenic above ~10,000 IU/day.

    Dosing & bioavailability

    Typical dose
    700–900 mcg RAE
    Upper safe limit
    3,000 mcg RAE
    Best form
    Mixed with food
    With food?
    Yes (fat-soluble)

    Where to buy

    Affiliate-style search links to reputable retailers. We don't endorse specific brands — verify third-party testing (USP, NSF, Informed Sport) before purchase.

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    Practitioner-grade · NSF tested

    Scientific evidence (9)

    Systematic reviewExamine.com Supplement Database · 2023

    Vitamin A (Retinol): pharmacology, clinical evidence, and safety — narrative review

    Examine.com Research Team

    Curated narrative review of human and preclinical evidence for Vitamin A (Retinol), including mechanism, typical dosing, and safety considerations.

    Key findings

    Best-supported outcome: Prevents xerophthalmia / night blindness (evidence: strong). Additional outcomes and limitations summarized in the full profile.

    Open study
    Systematic reviewPubMed (NLM) · 1970

    PubMed: Vitamin A (Retinol) — Prevents xerophthalmia / night blindness

    Live PubMed search

    Live results for "Vitamin A (Retinol) Prevents xerophthalmia / night blindness" across the PubMed/MEDLINE peer-reviewed index.

    Key findings

    Opens current human and preclinical literature matching Vitamin A (Retinol) and "Prevents xerophthalmia / night blindness". Filter by RCT, meta-analysis, or year on the results page.

    Open study
    Systematic reviewPubMed (NLM) · 1970

    PubMed: Vitamin A (Retinol) — Reduces measles mortality in deficient children

    Live PubMed search

    Live results for "Vitamin A (Retinol) Reduces measles mortality in deficient children" across the PubMed/MEDLINE peer-reviewed index.

    Key findings

    Opens current human and preclinical literature matching Vitamin A (Retinol) and "Reduces measles mortality in deficient children". Filter by RCT, meta-analysis, or year on the results page.

    Open study
    Systematic reviewPubMed (NLM) · 1970

    PubMed: Vitamin A (Retinol) — randomized controlled trial

    Live PubMed search

    Live results for "Vitamin A (Retinol) randomized controlled trial" across the PubMed/MEDLINE peer-reviewed index.

    Key findings

    Opens current human and preclinical literature matching Vitamin A (Retinol) and "randomized controlled trial". Filter by RCT, meta-analysis, or year on the results page.

    Open study
    Systematic reviewPubMed (NLM) · 1970

    PubMed: Vitamin A (Retinol) — meta-analysis

    Live PubMed search

    Live results for "Vitamin A (Retinol) meta-analysis" across the PubMed/MEDLINE peer-reviewed index.

    Key findings

    Opens current human and preclinical literature matching Vitamin A (Retinol) and "meta-analysis". Filter by RCT, meta-analysis, or year on the results page.

    Open study
    Systematic reviewPubMed (NLM) · 1970

    PubMed: Vitamin A (Retinol) — pharmacokinetics

    Live PubMed search

    Live results for "Vitamin A (Retinol) pharmacokinetics" across the PubMed/MEDLINE peer-reviewed index.

    Key findings

    Opens current human and preclinical literature matching Vitamin A (Retinol) and "pharmacokinetics". Filter by RCT, meta-analysis, or year on the results page.

    Open study
    Systematic reviewPubMed (NLM) · 1970

    PubMed: Vitamin A (Retinol) — safety adverse events

    Live PubMed search

    Live results for "Vitamin A (Retinol) safety adverse events" across the PubMed/MEDLINE peer-reviewed index.

    Key findings

    Opens current human and preclinical literature matching Vitamin A (Retinol) and "safety adverse events". Filter by RCT, meta-analysis, or year on the results page.

    Open study
    Systematic reviewPubMed (NLM) · 1970

    PubMed: Vitamin A (Retinol) — dose response

    Live PubMed search

    Live results for "Vitamin A (Retinol) dose response" across the PubMed/MEDLINE peer-reviewed index.

    Key findings

    Opens current human and preclinical literature matching Vitamin A (Retinol) and "dose response". Filter by RCT, meta-analysis, or year on the results page.

    Open study
    Systematic reviewGoogle Scholar · 1970

    Google Scholar: Vitamin A (Retinol) — clinical evidence

    Live Scholar search

    Cross-database citation index for Vitamin A (Retinol) as it relates to "clinical evidence".

    Key findings

    Includes preprints, theses, and journal articles. Useful for tracking citation counts and follow-on work.

    Open study
    Educational use only. This profile is not medical advice. Consult a qualified healthcare professional before starting any supplement, especially if you take prescription medication or have a chronic condition.