Bioavailability of elemental iron powders in bread assessed with an in vitro digestion/Caco-2 cell culture model

Iron fortification of staple foods is arguably the most widely used strategy for increasing the iron intake of populations. Although FeSO4 is a bioavailable form of iron, elemental iron powders are often used to fortify products with a long shelf-life, such as wheat flours, to avoid problems associated with the reactive nature of FeSO4. Therefore, the objectives of this study were to compare the bioavailabilities of elemental iron powders manufactured with different production methods in wheat flour breads and to determine the effects of added ascorbic acid and baking, using an in vitro digestion/Caco-2 cell culture model. Two types of wheat flour (low-extraction and high-extraction) were fortified with 10 different commercial elemental iron powders and baked into breads. iron bioavailabilities from the resulting breads, with and without added ascorbic acid, were evaluated using FeSO4 as the control. Depending on the type of wheat flour, bloavallabilities of several powders were comparable to FeSO4, but there was no consistent trend as to which production method produced the most bioavailable powder. In general, ascorbic acid enhanced, whereas the baking process reduced iron bioavailability from bread. Our results suggest that some elemental iron powders are potential alternatives to FeSO4. Human studies are warranted before any of these powders are selected for national fortification programs.