what form should vitamin a be in
Two forms of vitamin A are available in the human diet: preformed vitamin A (retinol and its esterified form, retinyl ester) and provitamin A carotenoids [ 1-5 ]. Preformed vitamin A is found in foods from animal sources, including dairy products, fish, and meat (especially liver).By far the most important provitamin A carotenoid is beta-carotene; other provitamin A carotenoids are alpha-carotene and beta-cryptoxanthin.he amounts of vitamin A in stand-alone supplements range widely [ 2 ]. Multivitamin supplements typically contain 2,500â10,000 IU vitamin A, often in the form of both retinol and beta-carotene. About 28%â37% of the general population uses supplements containing vitamin A [ 9 ].