PARTNERSHIP: BIOAVAILABILITY OF PROVITAMIN A CAROTENOIDS AND ZINC FROM BIOFORTIFIED MAIZE AND THE IMPACT ON HUMAN HEALTH

We will select agronomically promising high ß-cryptoxanthin (ßCX) and high zinc (Zn) maize varieties in Mexico and evaluate the elite cultivars in Texas. We will develop and select open-pollinated varieties using elite lines with high concentrations of ßCX and Zn in the grain in Mexico under subtropical conditions. We will further evaluate the selected germplasm lines in the semi-arid to sub-humid climate of Texas in high pH soils that limit bioavailability of Zn to maize. We will conduct field and laboratory screening to select the best varieties with the highest micronutrient content to be used in animal models and a human efficacy study. In the animal studies, we will determine the influence of ßCX-biofortified maize on zinc bioavailability to hen eggs compared with ß-carotene-biofortified maize and test bioefficacy of the biofortified maize and eggs in Mongolian gerbils. Animal models appropriate for carotenoid metabolism are few. This study will determine the difference in Zn bioavailability to eggs from hens fed maize biofortified with ßCX or ß-carotene. We will utilize the egg yolks collected from laying hens to evaluate their vitamin A and Zn nutritional value in gerbils. Provitamin A carotenoids are converted to vitamin A during times of vitamin A depletion in gerbils similarly to humans. Investigating health effects of biofortified maize and eggs are essential for marketing enhanced food products.Finally, we will orchestrate a ßCX- and Zn-biofortified maize intervention study in Mexican schoolchildren to assess vitamin A and Zn status and influence on gut microbiome. We will assess changes in total body vitamin A stores and estimate changes in total liver vitamin A reserves with a randomized intervention study using retinol isotope dilution techniques. We will evaluate the impact of biofortified maize feeding on Zn status using changes in serum concentrations. We will evaluate changes in fecal microbiome in a subset of the children between the biofortified maize and negative control groups.