The β-carotene-rich alga Dunaliella bardawil as a source of retinol in a rat diet

Abstract

1. Dunaliella bardawil, a β-carotene-accumulating alga, has been tested as a source of retinol and β-carotene in a diet given to rats. The β-carotene in this alga is composed of about equal amounts of the 9-cis and all-trans isomers. Male weanling rats were fed on a retinol-deficient diet for 60 d. Thereafter, the rats were divided into groups and fed on a diet deficient in retinol or supplemented with retinol, synthetic β-carotene, dry alga or an algal oil-extract. Following further growth for 7 d, samples were taken for liver analyses of retinol, retinol isomers and β-carotene.2. Liver analyses revealed a comparable content of retinol and normal conversion rates in the rats grown on the diets supplemented with synthetic or natural β-carotene. Rats fed on the alga and the algal-oil-supplemented diets accumulated 9-cis retinol in addition to the all-trans isomer. Rats fed on synthetic β-carotene, alga and algal oil had a liver retinol: β-carotene value of about 3:1.3. These studies demonstrate the possibility of using dried D. bardawil or an oil extract of the alga as a dietary natural β-carotene supplement which satisfies the total requirement of retinol in rats.4. Rats fed on alga or on algal oil, accumulated in the liver 9-cis β-carotene and all-trans β-carotene in a ratio similar to that present in the alga.