A novel, high precision multiple‐meal stable isotope method to compare iron absorption from extruded FePP‐fortified rice containing different zinc compounds, citric acid/trisodium citrate and EDTA in Ghanaian children

Abstract

Rice fortification can be a viable approach to combat iron deficiency in rice‐consuming populations, but it is crucial to identify micronutrient formulations with high iron bioavailability and acceptable sensory properties. To date, ferric phosphates are the only iron compounds resulting in sensory acceptable iron fortified rice grains.We measured fractional iron absorption (FAFe) from isotopically labeled ferric‐pyrophosphate (54FePP, 57FePP, 58FePP) in a cross‐over multiple meal absorption study. Fortified extruded rice meals either contained: zinc oxide (ZnO; 54FePP+ZnO), zinc sulphate (ZnSO4; 57FePP+ZnSO4), alone or in combination with a citrate buffer CA/TSC (54FePP+ZnO+CA/TSC or 57FePP+ZnSO4+CA/TSC) or ZnO, CA and edetate (EDTA; 58FePP+ZnO+CA+EDTA).Iron depleted school‐age children with and without anemia (N=26) in Northern Ghana were fed six different rice meals (all meals containing 2mg iron) over the course of six weeks. Each type of meal was administered twice daily for five consecutive days. FAFe was compared from meals 54FePP+ZnO, 57FePP+ZnSO4, 54FePP+ZnO+CA/TSC, 57FePP+ZnSO4+CA/TSC, 58FePP+ZnO+CA+EDTA versus non‐fortified extruded rice with 58FeSO4 (reference) added after cooking. FAFe was measured as erythrocyte‐incorporation of stable iron isotopes at least 11 days after meal‐administration.Geometric mean FAFe (95% CI) from meals 54FePP+ZnSO4+CA/TSC (6.3%; 5.3,7.4) and 58FePP+ZnO+CA+EDTA (6.5%; 5.3,8.1) did not differ from the reference (6.6%; 5.4,8.1). FAFe between 57FePP+ZnSO4 (3.5%; 2.7,4.5) and 54FePP+ZnO+CA/TSC (4.4%; 3.6,5.5) was not different, but both differed from 54FePP+ZnSO4+CA/TSC, 58FePP+ZnO+CA+EDTA and the reference (P<0.038), however, 54FePP+ZnO (2.3%; 1.9,2.8) showed the lowest FAFe and significantly differed from all other meals (P<.035).ConclusionsIron absorption from FePP‐fortified rice is affected by both the zinc source (ZnO or ZnSO4) and absorption enhancers (CA/TSC and CA+EDTA). For maximal iron absorption, rice fortification should be implemented using ZnSO4 as the zinc fortificant and CA/TSC or CA+EDTA as iron absorption enhancers.Support or Funding InformationThis study was funded by the Laboratory of Human Nutrition, DSM Nutritional Products, USAID and Abbott Nutrition.