Bioconversion of Carotenoids in Five Fruits and Vegetables to Vitamin A Measured by Retinol Accumulation in Rat Livers

Abstract

Problem statement: Vitamin A deficiency is one of the most prevalent and major nutritional problems in developing countries, especially in young children. In many countries, a substantial proportion of dietary vitamin A is commonly derived from pro-vitamin A carotenoids obtained from colored fruits and orange or green vegetables. However, the bioavailability of retinol derived from carotenoids from these plant sources is not well known. Approach: The present study analyzed β-Carotene and Total Carotenoids (TC) composition of carrots (Daucus carota), parsley (Petroselinum crispum), Spinach (Spinacea oleracea), mangoes (Mangifera indica) and papayas (Carica papaya) and determined the bioconversion of their carotenoids to vitamin A by monitoring the levels of retinol accumulated in liver and plasma of Wistar rats (Rattus norvegicus). Products were freeze-dried, β-Carotene content analyzed by HPLC and TC by Spectrophotometry. Results: Carrots presented the highest content of β-carotene followed by parsley with 32.8 and 19.6 mg 100 g^-1, respectively. Spinach had the highest content of TC followed by parsley with 60.7 and 56.7 mg 100 g^-1, respectively. Four-week-old male Wistar rats received a standard diet as an adaptation period, a diet free of Carotenoids and Vitamin A (CVA-diet) as depletion period and finally a Fruit or Vegetable (FoV) based diet as repletion period. The highest β-carotene bioconversion was for mango and the lowest for parsley, whereas the highest TC bioconversion was for carrots and the lowest for parsley. There were no significant differences in plasma retinol between treatments. Conclusion/Recommendations: There was no relation between carotenoids content in FoV-based diet and retinol status in plasma. Furthermore, the employment of a general retinol conversion factor is regarded as not appropriate. So, it is recommended to consider specific conversion factors for groups of horticultural crops, for example, a factor for green leafy vegetables and other factor for fruits or roots.