Vitamin A (Retinol)

Essential fat-soluble vitamin critical for vision, immune function, and cellular development

Scientific nameRetinol FormulaC20H30O Molecular weight286.45 g/mol CAS68-26-8

70 absorption score

6 safety / 10

10 USD per month

5 documented interactions

Check it against something

Evidence level A

Vitamin A (Retinol) with:

94 out of 100

Works better together Compatible. Timing differs, so follow each supplement's own window.

Check it against your whole stack →

What it does

mechanism and evidence for each claim

Vision support

Essential for rhodopsin production and night vision

Forms visual pigments in retinal cells Evidence A-grade 2-4 weeks

Immune function

Enhances resistance to infections

Maintains epithelial barriers and supports T-cell function Evidence A-grade 4-6 weeks

Skin health

Promotes healthy skin cell turnover

Regulates keratinocyte differentiation Evidence A-grade 6-8 weeks

Reproductive health

Essential for normal reproduction and fetal development

Regulates gene expression in reproductive tissues Evidence A-grade 8-12 weeks

Cell differentiation

Controls proper cell growth and specialization

Acts as transcriptional regulator Evidence A-grade 4-8 weeks

Others take these for the same thing

Same goal, different mechanism — check any of them against this one

Probiotics for Autoimmune Disease Support Gut health & immune modulation 10-100 billion CFU daily B 60% Vitamin D3 Bone health & immune support 1000-2000 IU A 85% Zinc Picolinate Superior immune & healing support 15-30 mg A 95% L-Lysine Immune support & collagen synthesis 1-3g A 90% Oregano Oil Powerful respiratory antimicrobial 100-300mg B 85% Oregano Oil for Antimicrobial Protection Antimicrobial & pathogen defense 1-3 drops diluted daily B 75%

Every pair we checked

12 combinations scored by the engine

Vitamin A (Retinol) + Caffeine No documented interaction either way No known interaction 70

Vitamin A (Retinol) + Creatine Monohydrate No documented interaction either way No known interaction 70

Vitamin A (Retinol) + Whey Protein No documented interaction either way No known interaction 70

Vitamin A (Retinol) + Turmeric No documented interaction either way No known interaction 70

Vitamin A (Retinol) + Vitamin A (Beta-Carotene) May interfere with vitamin A utilization Needs attention 82

Vitamin A (Retinol) + Lactase Improved calcium absorption when consuming dairy Works better together 82

Vitamin A (Retinol) + Bovine Collagen Essential for collagen synthesis and cross-linking Works better together 82

Vitamin A (Retinol) + DHA Prevents oxidation of DHA and enhances stability Works better together 82

Vitamin A (Retinol) + Vitamin D3 Protects vitamin A from oxidation Works better together 90

Vitamin A (Retinol) + Calcium Carbonate Essential for calcium absorption and utilization Works better together 94

Vitamin A (Retinol) + Zinc Gluconate Required for vitamin A transport and utilization Works better together 99

Vitamin A (Retinol) + Iron Sulfate Needed for beta-carotene conversion Works better together 99

Dosage

With fat meal

Daily2500-5000 IU

Maintenance2500-5000 IU

Therapeutic5000-8000 IU

Maximum10000 IU

Toxic25000+ IU daily for weeks

Upper limit 3000 mcg RAE NIH ODS

Before you take it

Pregnancyavoid high doses — teratogenic

VeganYes

When to expect it

First Effects1-2 weeks for vision improvements

Peak Benefits6-8 weeks for immune and skin benefits

Deficiency Development6-12 months with inadequate intake

Toxicity OnsetWeeks to months with excessive intake

How to measure it

$40-60

MarkerSerum retinol

Optimal30-70 μg/dL (1.05-2.44 μmol/L)

Deficient below20 μg/dL (0.70 μmol/L)

FrequencyAnnually if supplementing, or when symptoms present

What people actually reported to the FDA

CAERS, 34 reports naming it as the suspect

Most reported effects

Dizziness 5

Headache 4

Vomiting 4

Abdominal pain 4

Nausea 3

Named as the suspect 34 reports of 187 that mention it at all

Serious outcome 78% hospitalisation, emergency room or worse

Other Serious or Important Medical Event29

Visited a Health Care Provider10

Hospitalization8

Reports are voluntary and unverified — they record what someone experienced while taking something, not what the compound caused. Counts skew towards products people take a lot of, and a serious outcome is more likely to be reported than a mild one, so these are not rates. How we filter them →

Works better with

3 documented

Vitamin E

Protects vitamin A from oxidation

Antioxidant protection in storage and transport · level A

Zinc

Required for vitamin A transport and utilization

Component of retinol-binding protein · level A

Iron

Needed for beta-carotene conversion

Cofactor for carotenoid cleavage enzymes · level B

What not to take with Vitamin A (Retinol)

2 documented

Beta Carotene Excess

May interfere with vitamin A utilization

Competition for absorption and transport · mild significance

Alcohol

Interferes with vitamin A storage and metabolism

Competes for ADH enzymes and depletes stores · moderate significance

Medication interactions

Discuss these with a pharmacist before combining

isotretinoin-accutane Major

Additive toxicity risk

What to do: Avoid vitamin A supplements completely

tetracycline-antibiotics Moderate

Increased intracranial pressure risk

What to do: Monitor for headache and vision changes

Available forms

bioavailability compared

Retinyl Palmitate 70

Retinyl Acetate 75

Beta-carotene 30

Retinyl Palmitate: Stable form, Most common supplement, Good absorption

Retinyl Acetate: Slightly better absorption, Stable

Beta-carotene: No toxicity risk, Natural antioxidant, Self-regulating

Food sources

before you supplement

Beef liver 16898 IU/100g · 90

Cod liver oil 30000 IU/100g · 85

Sweet potato 14187 IU/100g (as beta-carotene) · 25

Carrots 16706 IU/100g (as beta-carotene) · 20

Too little

deficiency signs

Night blindness and poor dark adaptation
Dry eyes and corneal damage
Frequent infections
Dry, rough skin
Poor wound healing
Growth retardation in children
Infertility issues

Too much

toxicity signs

Headache and dizziness
Nausea and vomiting
Liver damage
Bone and joint pain
Skin peeling and hair loss
Birth defects if pregnant
Hypercalcemia

Who benefits most

night-shift-workers

Higher needs for visual adaptation

3000-5000 IU daily

frequent-travelers

Increased infection risk and immune stress

2500-4000 IU daily

acne-sufferers

Supports healthy skin cell turnover

2500-5000 IU daily

elderly

Reduced absorption and immune function

2500-4000 IU daily

vegans

No preformed vitamin A in plant foods

Focus on beta-carotene conversion

Where to buy it

compare forms first

Look for Vitamin A (Retinol) at 2500-5000 IU per serving. The form that matters here is Retinyl Palmitate.

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What else affects it

Beyond other supplements

Alcohol

Interferes with vitamin A storage and metabolism

Competes for ADH enzymes and depletes stores

How it works

Visual cycle in retinal photoreceptors
Gene transcription regulation via RAR/RXR receptors
Epithelial cell differentiation and maintenance
Immune cell development and function
Antioxidant activity (as carotenoids)
Protein synthesis regulation

Key findings

what the evidence supports

Reduces child mortality by 24% in deficient populations (WHO 2017)
Essential for immune function development (Nature Reviews 2018)
Critical for vision and prevents night blindness (Cochrane 2016)
Supports healthy pregnancy outcomes (NEJM 2019)

Sources: NIH Examine.com · data reviewed 2026-08-02

Compiled by Denis, who maintains this database and holds no medical qualification — every figure here is sourced or derived, never asserted. How we calculate it →

Common questions

What are the benefits of Vitamin A (Retinol)?

Documented effects: Vision support; Immune function; Skin health; Reproductive health. Essential for rhodopsin production and night vision

How much Vitamin A (Retinol) should you take per day?

The common daily range is 2500-5000 IU. By goal — maintenance: 2500-5000 IU; therapeutic: 5000-8000 IU; maximum: 10000 IU; toxic: 25000+ IU daily for weeks.

When is the best time to take Vitamin A (Retinol)?

With fat meal. First effects are typically reported within 1-2 weeks for vision improvements.

What are the side effects of Vitamin A (Retinol)?

At excessive doses: Headache and dizziness, Nausea and vomiting, Liver damage, Bone and joint pain, Skin peeling and hair loss. Safety rating at normal doses is 6 out of 10.

What should you not take with Vitamin A (Retinol)?

Separate it from Beta Carotene Excess, Alcohol by two to four hours. May interfere with vitamin A utilization

Does Vitamin A (Retinol) interact with medications?

Documented interactions with isotretinoin-accutane, tetracycline-antibiotics. Discuss these with a pharmacist before combining.

How much Vitamin A (Retinol) is too much?

The tolerable upper intake level is 3000 mcg RAE per day for adults, per NIH ODS. Above that, the risk of adverse effects rises: Headache and dizziness, Nausea and vomiting, Liver damage.

How do you know if you need Vitamin A (Retinol)?

The marker is Serum retinol, optimal range 30-70 μg/dL (1.05-2.44 μmol/L). Common deficiency signs: Night blindness and poor dark adaptation, Dry eyes and corneal damage, Frequent infections, Dry, rough skin.

Taken for

59 Immunity

Vitamin D3 · Vitamin C (Ascorbic Acid) · Comprehensive Immune Support Complex