Liver Storage of Vitamin A in Rats Fed Carotene Stereoisomers

Abstract

Provitamin A activity values were determined for the principal carotene stereoisomers present in vegetables, or produced by vegetable processing. Carotenes investigated were all-trans-β-carotene, neo-β-carotene B (9,13-di cis), neo-β-carotene U (9-mono cis), all-trans-α-carotene, neo-α-carotene B (13,9′-di cis), and neo-α-carotene U (9-mono cis). Assays of vitamin A were made by measurement of vitamin A storage in rats fed the isomers. Results showed consistently higher liver storage values for cis isomers than values obtained by others using growth response assays. The high values would indicate that formation of isomers at the expense of all-trans carotenes would result in smaller decreases in provitamin A activity than those calculated using the growth response values. For all-trans-α-carotene, liver storage values were lower than values that have been obtained by the growth assay. The amount of vitamin A stored in the kidneys was small compared to that stored in the liver. The weight of the rats at age 21 days, the beginning of depletion, appeared to be related to vitamin A liver storage. Rats heaviest in weight at 21 days usually had the greatest subsequent storage.