Vitamin A is available in 2 forms in the human diet: preformed vitamin A (retinol and its esterified form, retinyl ester) and provitamin A carotenoids.
ສອງຮູບແບບຂອງວິຕາມິນ A ທີ່ມີຢູ່ໃນອາຫານຂອງມະນຸດ: preformed ວິຕາມິນ A (retinol ແລະຮູບແບບ esterified ຂອງຕົນ, retinyl ester) ແລະ carotenoids provitamin A.