Micronization of wholewheat flour increases iron bioavailability from hydrothermally processed wheat flour dough

Cereal products contribute significantly to dietary intake of essential minerals. In wheat, iron and zinc are stored in specific grain structures including the aleurone, scutellum and embryo. Wheat cell walls are resistant to digestion in the human gastrointestinal tract and therefore this study investigated the hypothesis that physical disruption of the cell walls would increase the bioaccessibility and bioavailability of iron and zinc from wheat-based foods. Flour was micronized using a combination of roller milling and a micro-mill and this reduced median particle size by two-thirds. Hydrothermally processed wheat flour doughs were subjected to in vitro digestion to determine mineral bioaccessibility. Mineral bioavailability from food digests was measured using human intestinal Caco-2 cells. Iron (but not zinc) bioavailability from wheat foods made using the micronized flour (2.5 ± 0.5 nmol/mg cell protein) was increased significantly compared with foods produced from standard milled flour (1.3 ± 0.1 nmol/mg cell protein; P = 0.031). Micronization of wheat flour has the potential to increase the absorption of the endogenous iron present in cereal foods and this might have health benefits for population groups with poor iron status.