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Vitamin A Research & Evidence

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Evidence Level

Strong

Vitamin A's essential role in human health is supported by decades of research. A landmark Lancet meta-analysis by Imdad et al. (2010) of 43 trials (n=215,633 children) found that vitamin A supplementation reduced all-cause mortality by 24% and diarrhea-related mortality by 28% in deficient populations. The AREDS2 trial (2013) demonstrated that a formulation including beta-carotene alternatives (lutein/zeaxanthin) slowed progression of age-related macular degeneration. However, the ATBC and CARET trials showed that high-dose beta-carotene supplementation increased lung cancer risk in smokers by 18-28%, leading to recommendations against supplementation in this population.

Evidence by Condition

ConditionStudied DoseEvidence
General health700-900 mcg RAE dailyStrong
Immune support900 mcg RAE daily from food or mixed carotenoidsStrong
Skin health700-900 mcg RAE daily; topical retinoids separatelyModerate
Eye health700-900 mcg RAE daily, often combined with lutein and zeaxanthinStrong
Full Vitamin A Guide

References

  1. (). Vitamin A supplementation for preventing morbidity and mortality in children from 6 months to 5 years of age. Cochrane Database of Systematic Reviews. DOI
  2. (). Lutein + zeaxanthin and omega-3 fatty acids for age-related macular degeneration: the AREDS2 randomized clinical trial. JAMA. DOI
  3. (). The effect of vitamin E and beta carotene on the incidence of lung cancer and other cancers in male smokers. New England Journal of Medicine. DOI