Vitamin A (Retinol / Retinyl Palmitate)
Wellness
In plain English
Vitamin A is an essential vitamin needed for vision, immune function, skin, and cell growth. Correcting a true deficiency has powerful health benefits, especially in populations where deficiency is common. However, vitamin A is fat-soluble and builds up in the body, so too much is toxic — and it is especially dangerous in pregnancy, where excess can cause birth defects. Supplementation beyond correcting deficiency is not clearly beneficial.
The science
Vitamin A (retinol and esters such as retinyl palmitate) is essential for photoreceptor function, epithelial integrity, immune defense and regulation of gene expression via retinoic acid receptors. Landmark randomized community trials showed that vitamin A supplementation substantially reduced childhood mortality in deficient populations (Sommer et al., Lancet 1986), establishing its public-health importance where deficiency is endemic. Because it is fat-soluble and accumulates, excess causes acute or chronic hypervitaminosis A (headache, hepatotoxicity, bone effects) and is teratogenic — high-dose vitamin A must be avoided in pregnancy. Benefit in vitamin-A-replete individuals is limited; routine high-dose supplementation is not recommended without deficiency.