ABSTRACT
In 1930, Moore discovered that b-carotene (b-C) could be converted in vivo to vitamin A (1). Since then, the vitamin A value of dietary b-C and other provitamin A carotene products, in addition to their other biological activities,
have been investigated. It is now known that the bioequivalence of provitamin A
carotenoids in humans varies greatly, probably as a result of environmental and
genetic factors.
