Retinol Equivalence of Carotenoids Can be Evaluated by Hepatic Vitamin A Content

The present study demonstrates a new method to evaluate the bioavailability of carotenoids based on the calculation of the hepatic retinol contents. Weaning male rats of Wistar strain were divided into 5 groups. Each group respectively received retinol acetate (2000–10000 IU per kg diet), alpha-carotene (2400–6000 mug per kg diet), beta-carotene (2400–6000 mug per kg diet), mixture of alpha- and beta-carotenes in the ratio of 1:2 (2400 and 4800 mug per kg diet), and palm-carotene oil (2400–6000 mug per kg diet). The derived retinol equivalences of each carotenoid calculated according to the hepatic retinol contents were almost constant regardless of the volume of respective intake (alpha-carotene: 1.25 mug per IU; beta-carotene: 0.59 mug per IU; mixture of alpha- and beta-carotene in the ratio of 1:2: 0.96 mug per IU; Palm-carotene oil: 1.23 mug per IU). The results suggest that the hepatic retinol contents can be used as a new measure to evaluate the vitamin A bioavailability of carotenoids.