Iron Bioavailability in Corn-Masa Tortillas Is Improved by the Addition of Disodium EDTA

Abstract

Corn-masa flour flat bread tortillas are the main staple of Mexican and Central American populations. Due to high concentrations of inhibitors of iron absorption, the bioavailability from this matrix is unknown. We wanted to determine the most suitable fortificant that would efficaciously improve iron bioavailability. In tortillas prepared with commercial precooked, lime-treated, corn-masa flour, we examined the in vitro solubility of the following forms of iron: native iron with and without Na₂EDTA, elemental reduced iron plus Na₂EDTA, ferrous fumarate with and without Na₂EDTA, bisglycine iron, ferrous sulfate and NaFeEDTA. We also examined the in vivo bioavailability in humans with double radioiron erythrocyte incorporation of ferrous fumarate with and without Na₂EDTA, bisglycine iron, NaFeEDTA and native iron plus Na₂EDTA, beans and rice. In vitro, solubility ranged from 1% in iron forms without Na₂EDTA to 19.4% for NaFeEDTA. Forms of iron with Na₂EDTA had intermediate values. In vivo radioiron studies showed that iron forms without Na₂EDTA also had low bioavailability (≤1%). NaFeEDTA had the highest bioavailability (5.3%). The bioavailability of all iron forms improved significantly when tested with Na₂EDTA (2EDTA to ferrous fumarate increased bioavailability from 0.87% to 2.9% (P < 0.001). We conclude that NaFeEDTA is the form of iron best absorbed, but alternatively, ferrous fumarate plus Na₂EDTA comprises a feasible option as a fortificant.