Zinc Bioavailability From Amaranth-enriched Maize Tortillas

This is a randomized cross-over study of zinc absorption in young children living in the Western Highlands of Guatemala. Absorption of zinc will be measured from maize tortillas and maize tortillas fortified with 20% amaranth as the major food staple which provides at least 70% energy and at least 90% zinc and phytate of the diet. Participants will be randomized as to which type of tortilla they receive on the first and second day. Fractional absorption of zinc (FAZ) from all meals in one day for one type of tortilla and one day for the other will be measured by extrinsic labeling with stable isotopes of zinc. FAZ will be measured by a dual isotope tracer ratio (DITR) technique based on ratio of urine enrichment of orally versus intravenously administered zinc stable isotopes. Measurement of total zinc in duplicate diets on test days allow for determination of quantities of this micronutrient absorbed.