Vitamin A Value of Plant Food Provitamin A - Evaluated by the Stable Isotope Technologies

Abstract

Abstract:Humans need vitamin A and obtain essential vitamin A by conversion of plant foods rich in provitamin A and/or absorption of preformed vitamin A from foods of animal origin. The determination of the vitamin A value of plant foods rich in provitamin A is important but has challenges. The aim of this paper is to review the progress over last 80 years following the discovery on the conversion of β-carotene to vitamin A and the various techniques including stable isotope technologies that have been developed to determine vitamin A values of plant provitamin A (mainly β-carotene). These include applications from using radioactive β-carotene and vitamin A, depletion-repletion with vitamin A and β-carotene, and measuring postprandial chylomicron fractions after feeding a β-carotene rich diet, to using stable isotopes as tracers to follow the absorption and conversion of plant food provitamin A carotenoids (mainly β-carotene) in humans. These approaches have greatly promoted our understanding of the absorption and conversion of β-carotene to vitamin A. Stable isotope labeled plant foods are useful for determining the overall bioavailability of provitamin A carotenoids from specifi c foods. Locally obtained plant foods can provide vitamin A and prevent defi ciency of vitamin A, a remaining worldwide concern.Key words: stable isotopes, vitamin A, provitamin A carotenoids, β-carotene, intrinsic labeling, bio absorption, bio conversion Vitamin A is an essential nutrient for humans. The human body obtains vitamin A from preformed vitamin A through foods of animal origin or from provitamin A carotenoids through foods of plant origin. Plant provitamin A carotenoids in foods have to be processed, cooked, absorbed and converted to vitamin A in the human body, which are the factors affecting the vitamin A value of the plant provitamin A carotenoids. Therefore, it is of importance to quantitatively determine the conversion effi ciency of plant provitamin A carotenoids to vitamin A, specifi cally the vitamin A value of a plant food. In 1930, Moore discovered that provitamin β-carotene can convert to vitamin A [1]. Since then, the vitamin A value of provitamin A carotenoids has been investigated through many approaches involving various technologies. The aim of this paper is to review the progress over the last 80 years following this discovery of the conversion of β-carotene to vitamin A and the development of various techniques including stable isotope technologies to determine the vitamin A values of plant provitamin A.In 1980, the Recommended Dietary Allowances [2] stated that "Although the enzymatic conversion of

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Use of Stable Isotopes to Evaluate Bioefficacy of Provitamin A Carotenoids, Vitamin A Status, and Bioavailability of Iron and Zinc

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