Bioaccessibility of Pro-Vitamin A Carotenoids Is Minimally Affected by Non Pro-Vitamin A Xanthophylls in Maize (Zea mays sp.)

Abstract

The absorption of some carotenoids has been reported to be decreased by coingestion of relatively high concentrations of other carotenoids. It is unclear if such interactions occur among carotenoids during the digestion of plant foods. Current varieties of maize contain limited amounts of the pro-vitamin A (pro-VA) carotenoids beta-carotene (BC) and beta-cryptoxanthin (BCX) and relatively higher levels of their oxygenated metabolites lutein (LUT) and zeaxanthin (ZEA). Here, we examined if LUT and ZEA attenuate the bioaccessibility of pro-VA carotenoids at amounts and ratios present in maize. BC incorporation into bile salt mixed micelles during chemical preparation and during simulated small intestinal digestion of carotenoid-enriched oil was slightly increased when the concentration of LUT was sixfold or more greater than BC. Likewise, the efficiency of BC micellarization was slightly increased during simulated small intestinal digestion of white maize porridge supplemented with oil containing ninefold molar excess of LUT to BC. Mean efficiencies of micellarization of BC, BCX, LUT, and ZEA were 16.7, 27.7, 30.3, and 27.9%, respectively, and independent of the ratio of LUT plus ZEA to pro-VA carotenoids during simulated digestion of maize porridge prepared from flours containing 0.4-11.3 microg/g endogenous pro-VA carotenoids. LUT attenuated uptake of BC by differentiated cultures of Caco-2 human cells from medium-containing micelles in a dose-dependent manner with inhibition reaching 35% when the molar ratio of LUT to BC was 13. Taken together, these results suggest that the bioaccessibility of pro-VA carotenoids in maize is likely to be minimally affected by the relative levels of xanthophylls lacking pro-VA activity present in cultivars of maize.