Nutrients, Vol. 17, Pages 3891: Influence of Sourdough Fermentation-Induced Dephytinization on Iron Absorption from Whole Grain Rye Bread–Double-Isotope Crossover and Single-Blind Absorption Studies
Nutrients doi: 10.3390/nu17243891
Authors:
Michael Hoppe
Ann-Sofie Sandberg
Lena Hulthén
Background/Objectives: There are substantial beneficial health effects from a diet rich in whole grains. However, a high intake of whole grain, and hence a high intake of the iron absorption inhibitor phytate, may result in the impaired bioavailability of non-heme iron. The study examined non-heme iron absorption in healthy women from two portions (80 g and 120 g) of identical whole grain bread, baked with or without phytate-degrading techniques. Methods: The study included two single-blinded iron isotope trials. Subjects were served meals containing whole grain rye bread, which was either baked from scalded flour or sourdough-fermented flour labeled with 55Fe or 59Fe. The absorption of non-heme iron from the meals was measured through the erythrocyte incorporation of radioiron isotopes. Results: Iron absorption from the 80 g high-phytate bread was 7.0 ± 4.1% (mean ± SD, n = 8). Iron absorption from the 80 g dephytinized bread was 19.1 ± 15.1% (mean ± SD) and thus on average 2.8 times higher compared to the absorption from the high-phytate bread (p = 0.001). Iron absorption from the 120 g high-phytate bread was 4.6 ± 2.9% (mean ± SD, n = 17). Iron absorption from the 120 g dephytinized bread was 15.0 ± 9.2% (mean ± SD) and thus on average 3.5 times higher compared to the absorption from the high-phytate bread (p = 0.001). Conclusions: Iron uptake was significantly higher from dephytinized bread compared to scalded bread. And the higher the amount of phytate, the higher the beneficial effects on iron absorption from dephytinization.
Background/Objectives: There are substantial beneficial health effects from a diet rich in whole grains. However, a high intake of whole grain, and hence a high intake of the iron absorption inhibitor phytate, may result in the impaired bioavailability of non-heme iron. The study examined non-heme iron absorption in healthy women from two portions (80 g and 120 g) of identical whole grain bread, baked with or without phytate-degrading techniques. Methods: The study included two single-blinded iron isotope trials. Subjects were served meals containing whole grain rye bread, which was either baked from scalded flour or sourdough-fermented flour labeled with 55Fe or 59Fe. The absorption of non-heme iron from the meals was measured through the erythrocyte incorporation of radioiron isotopes. Results: Iron absorption from the 80 g high-phytate bread was 7.0 ± 4.1% (mean ± SD, n = 8). Iron absorption from the 80 g dephytinized bread was 19.1 ± 15.1% (mean ± SD) and thus on average 2.8 times higher compared to the absorption from the high-phytate bread (p = 0.001). Iron absorption from the 120 g high-phytate bread was 4.6 ± 2.9% (mean ± SD, n = 17). Iron absorption from the 120 g dephytinized bread was 15.0 ± 9.2% (mean ± SD) and thus on average 3.5 times higher compared to the absorption from the high-phytate bread (p = 0.001). Conclusions: Iron uptake was significantly higher from dephytinized bread compared to scalded bread. And the higher the amount of phytate, the higher the beneficial effects on iron absorption from dephytinization. Read More