Retinol replacement in deficient patients; dose and duration are clinician-directed
Reviewed · Published
Vitamin A
A fat-soluble vitamin required for vision, immunity, and epithelial differentiation.
Established functions
- A fat-soluble vitamin required for vision, immunity, and epithelial differentiation.
Dietary sources
- liver
- eggs
- carrots
Claims and evidence
Claims that Vitamin A alone prevents or treats disease, or invariably improves health without deficiency, are unsupported.
Japanese reference amounts
- Japanese adults (age and sex as specified): Adult men 850–900 µg RAE/day; women 650–700 µg RAE/day (RDA)
Amounts studied
- Retinol replacement in deficient patients; dose and duration are clinician-directed
Tolerable upper limits
- Adults: 2,700 µg RAE/day (excludes provitamin A)
Forms and bioavailability
Supplement forms: retinyl palmitate, beta-carotene
- Absorption improves with dietary fat; beta-carotene conversion varies.
Safety and interactions
Adverse effects
- headache
- dry skin
- liver injury
- teratogenicity
Medicine and nutrient interactions
- retinoids, orlistat, duplicate vitamin A
Contraindications and cautions
- Avoid high-dose retinol in pregnancy and high-dose beta-carotene in smokers.
Practical selection
- Compare Vitamin A amount per serving, form, allergens, and batch testing; prefer a single-ingredient product suited to the intended use.
Sources and review
- Dietary Reference Intakes for Japanese (2025)Ministry of Health, Labour and Welfare (Japan)
- NIH ODS vitamin fact sheetsNIH Office of Dietary Supplements
Daiki Minaki (editorial and evidence review) ·