Vitamin A (Retinol & Beta-Carotene)

Direct Answer

Vitamin A is an essential fat-soluble isoprenoid comprising preformed retinol and provitamin A carotenoids. Adult RDA is 900 µg RAE (men) / 700 µg RAE (women), with a Tolerable Upper Limit of 3,000 µg/day preformed retinol, essential for rhodopsin retinal photoreception, epithelial differentiation, and immune cell proliferation.

Source: NIH Office of Dietary Supplements / EFSA Dietary Reference Values · Last reviewed Aug 28, 2026

Specs

Nutrient Type	Fat-Soluble Isoprenoid Vitamin
Adult RDA / RDI	900 µg RAE / day (Men) / 700 µg RAE / day (Women)
Tolerable Upper Limit (UL)	3,000 µg / day (10,000 IU) (Preformed retinol only; no UL for beta-carotene)
Chemical Forms	Retinyl Palmitate (Preformed Animal), All-Trans Retinol, Beta-Carotene (Plant Provitamin)
Primary Biological Function	11-cis-retinal rhodopsin visual cycle, RAR/RXR nuclear receptor gene transcription, Mucosal barrier immunity
Deficiency Condition	Nyctalopia (Night blindness), Xerophthalmia, Bitot's spots, Keratinization of mucous membranes
Top Whole Food Sources	Beef Liver, Cod Liver Oil, Sweet Potatoes, Carrots, Spinach, Curly Kale, Butter
Hepatic Storage	80–90% of total body Vitamin A is stored in hepatic stellate cells as retinyl esters

RAE Conversion Equivalency

1 µg Retinol Activity Equivalent (RAE) = 1 µg of all-trans retinol = 2 µg of supplemental beta-carotene = 12 µg of dietary beta-carotene = 24 µg of dietary alpha-carotene or beta-cryptoxanthin.