Deficiency/Immunity/Beauty

Vitamin A

Fat-soluble vitamin essential for vision and immune function, most useful for adults with low intake or malabsorption.

Vitamin A

Fat-soluble vitamin essential for vision and immune function, most useful for adults with low intake or malabsorption.

score

evidence

Caution

risk

Proven Benefits

01Corrects vitamin A deficiency

02Restores night vision in deficiency

03Reduces measles complications

04Supports immune defense if low

05Supports skin barrier if low

06Improves hemoglobin if low

07May lower respiratory infections

08May improve acne

Chemical Forms

Recommended

Retinyl palmitate
Retinyl acetate
Beta-carotene

Avoid

High-dose synthetic beta-carotene in smokers/former smokers (higher lung cancer risk in trials)
Fish liver oils with unspecified vitamin A content (easy to overshoot when stacked with other products)

Expert Note

Retinyl palmitate and acetate provide preformed vitamin A with predictable potency, which is useful when intake is clearly low. Beta-carotene is converted as needed and is less likely to cause toxicity, but conversion varies between people. High-dose beta-carotene is not appropriate for smokers or recent former smokers because major trials found higher lung cancer risk.

Protocol

Amount

2500-3000 IU

Frequency

Once daily

When

With a meal containing fat to improve absorption.

Condition-Based Dosing

Adult women, not pregnant

2300 IU daily— About 700 mcg RAE; include diet plus supplements when estimating total preformed vitamin A.

Adult men

3000 IU daily— About 900 mcg RAE; routine higher doses rarely add benefit in replete adults.

Pregnant or trying to conceive

Avoid separate preformed vitamin A unless prescribed; use only the amount in a prenatal.— Excess retinol is teratogenic; beta-carotene is generally preferred if extra vitamin A is needed.

Safety & Limits

Upper Safe Limit

10000 IU/day preformed vitamin A (IOM UL for adults)

Cycling

Safe for continuous use

Contraindications

Pregnancy or trying to conceive — excess preformed vitamin A is teratogenic

Retinoid medications such as isotretinoin or acitretin — additive vitamin A toxicity risk

Chronic liver disease or heavy alcohol use — greater risk of liver injury

Smokers or recent former smokers using high-dose beta-carotene — linked to higher lung cancer risk in trials

History of hypervitaminosis A — recurrence risk with supplemental retinol

Synergies

Zinc

Zinc helps synthesize retinol-binding protein and mobilize vitamin A from the liver, so zinc deficiency can blunt vitamin A status improvement.

Dietary fat

Vitamin A is fat-soluble, so taking it with a meal that contains fat improves micelle formation and intestinal absorption.

Avoid Combining With

✕Orlistat (reduces fat absorption and lowers vitamin A uptake)
✕Bile acid sequestrants like cholestyramine (reduce absorption)
✕Mineral oil laxatives (impair fat-soluble vitamin absorption)
✕Very low-fat meals (lower absorption; take with food containing fat)

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