Vitamin A (retinol)
Essential fat-soluble nutrient with EFSA claims for vision, immune function, skin, and iron metabolism, narrow safe upper limit at therapeutic doses.
Why
Vitamin A is essential for vision (retinal pigment cycle), epithelial differentiation (skin, mucosa), immune function, and iron metabolism. EFSA has authorised health claims for all four of these. Two main dietary forms: preformed retinol (animal sources) and provitamin carotenoids (β-carotene from plants). Preformed retinol is teratogenic at high doses, pregnancy intake should not exceed 3,000 µg/day RAE. Smoker beta-carotene caution (ATBC, CARET trials) is well-established.
How it works
Retinaldehyde combines with opsin in retinal photoreceptors, basis of vision. Retinoic acid binds nuclear retinoic acid receptors regulating gene expression in epithelial differentiation. Modulates innate and adaptive immunity (cytokine production, T-cell maturation). Mobilises iron from hepatic stores.
Expected onset · Deficiency correction over weeks; preventive use ongoing
How to take
Dosage
RDI: 700–900 µg RAE/day. Supplement: 700–1,500 µg/day. Upper level (EFSA): 3,000 µg/day preformed retinol from supplements + diet.
Timing
With meals containing fat
On the label
'Retinol' or 'retinyl palmitate' (preformed). β-Carotene from food/algal source is the safer form for general supplementation in non-smokers. Stated µg RAE not just IU.
Ideal for
Adults with low dietary intake of yellow/orange vegetables and liver; vegetarians with restricted dietary sources; populations at risk of deficiency. Pregnant women: get from dietary sources only; supplement only under clinical guidance.
Safety
Evidence
EFSA-authorised claims for vision, immune function, skin/mucosa and iron metabolism, highest regulatory tier. ATBC 1994 NEJM RCT: β-carotene 20 mg/day increased lung cancer incidence by 18% in male smokers, defined the smoker-caution rule. Rothman 1995 NEJM established teratogenicity threshold around 3,000 µg retinol equivalents/day in early pregnancy.
- EFSA Reg 432/2012 authorised claims, vitamin A and normal vision, immune function, skin/mucosa maintenance, iron metabolism
- The Alpha-Tocopherol Beta Carotene Cancer Prevention Study Group, NEJM 1994, effect of vitamin E and beta carotene on the incidence of lung cancer (ATBC, n=29,133)
- Rothman et al., NEJM 1995, teratogenicity of high vitamin A intake
Where to get it
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