Vitamin A 1 article

Preformed retinoids and provitamin A carotenoids both contribute to the vitamin A category rather than representing one single chemical form. Liver, eggs, and some dairy foods provide preformed vitamin A, while orange vegetables and dark leafy greens supply carotenoids such as beta-carotene that can be converted to vitamin A. Food and supplement labels report vitamin A activity, so comparisons should distinguish retinol-based sources from carotenoid precursors and from carotenoids such as lycopene that do not provide vitamin A activity.