Phytic Acid Concentration Influences Iron Bioavailability from Biofortified Beans in Rwandese Women with Low Iron Status

Petry N, Egli I, Gahutu JB, Tugirimana PL, Boy E, Hurrell RF

September 2014 – Journal of Nutrition

The common bean is a staple crop in many African and Latin American countries and is the focus of biofortification initiatives. Bean iron concentration has been doubled by selective plant breeding, but the additional iron is reported to be of low bioavailability, most likely due to high phytic acid (PA) concentrations. To evaluate the impact of PA on iron bioavailability from iron-biofortified beans, a multiple-meal iron absorption crossover study was conducted in Rwandese women. Iron absorption was based on the erythrocyte incorporation of stable iron isotopes, and meals contained biofortified beans and control beans; beans tested either contained their native PA concentration and were dephytinized at ∼50% and >95%. The quantity of iron absorbed from the biofortified bean meals (406 μg) was 19% higher (P < 0.05) than that from the control bean meals. With ∼50% and >95% dephytinization, the quantity of iron absorbed from the biofortified bean meals increased to 599 and 746 μg, respectively, which was 37% (P < 0.005) and 51% (P < 0.0001) higher than from the control bean meals. PA strongly decreases iron bioavailability from iron-biofortified beans, and a high PA concentration is an important impediment to the optimal effectiveness of bean iron biofortification. Plant breeders should focus on lowering the PA concentration of high-iron beans.