Bread baking does not enhance the bioavailability of hydrogen reduced iron powder

Abstract

Elemental iron powders, widely used to fortify flour and cereal products, typically have relative biological values of ~50% compared to FeSO4. Our objective was to test the hypothesis that bread baking enhances the bioavailability of elemental iron powders by oxidizing elemental iron (Fe0) to Fe2+or Fe3+. Methods Bread baked with flour fortified with either hydrogen reduced (HR) Fe or FeSO4 (300 mg Fe/kg flour), or no added iron, was dried and milled. Diets contained 35% bread, 35% ground corn, 22% whey protein isolate, a mineral/vitamin premix, and 130 mg Fe/kg. A hemoglobin repletion assay with weanling, iron deficient piglets was used to assess bioavailability. Experiment 1 Crossbred piglets (Hampshire x Landrace x Yorkshire) were divided into two groups and fed diets containing bread fortified, pre-baking, with either FeSO4 or HR Fe. After 16 days, hemoglobin repletion efficiencies (HRE) in the piglets fed HR and FeSO4 fortified breads were 14.9% & 30.9%, respectively (p<0.001). Experiment 2 Similar to experiment 1 except a 3rd treatment consisting of unfortified bread with HR Fe added post-baking was included. After 14 days, HREs in piglets fed the unfortified bread plus HR Fe added post baking, HR Fe fortified bread, and FeSO4 fortified bread, were 6.6%, 8.9%, & 16.1%, respectively. HRE in the FeSO4 group was significantly higher but the 2 HR Fe groups were not different. We conclude that bread baking does not enhance the bioavailability of HR iron powders. Funded by College of Agriculture and Life Sciences, Cornell University.