Provitamin A carotenoids from an engineered high-carotenoid maize are bioavailable and zeaxanthin does not compromise β-carotene absorption in poultry

High-carotenoid (HC) maize, a biofortified staple crop which accumulates β-carotene, β-cryptoxanthin, lutein and zeaxanthin, was used as a feed component in a chicken feeding trial to assess the bioavailability of provitamin A (PVA) carotenoids in the kernel matrix compared to the synthetic and natural color additives routinely used in the poultry industry. We found that the PVA carotenoids in HC maize were not metabolized in the same manner: β-carotene was preferentially converted into retinol in the intestine whereas β-cryptoxanthin accumulated in the liver. We also considered the effect of zeaxanthin on the absorption of PVA carotenoids because zeaxanthin is the major carotenoid component of HC maize. We found that chickens fed on diets with low levels of zeaxanthin accumulated higher levels of retinol in the liver, suggesting that zeaxanthin might interfere with the absorption of β-carotene, although this observation was not statistically significant. Our results show that HC maize provides bioavailable carotenoids, including PVA carotenoids, and is suitable for use as a feed component.