In Rwandese Women With Low Iron Status, Iron Absorption From Low-Phytic Acid Beans And Biofortified Beans Is Comparable, But Low-Phytic Acid Beans Cause Adverse Gastrointestinal Symptoms

Background: Phytic acid (PA) is a major inhibitor of iron bioavailability from beans, and high PA concentrations might limit the positive effect of biofortified beans (BBs) on iron status. Low-phytic acid (Ipa) bean varieties could increase iron bioavailability.Objective: We set out to test whether Ipa beans provide more bioavailable iron than a BB variety when served as part of a composite meal in a bean-consuming population with low iron status.Methods: Dietary iron absorption from Ipa, iron-biofortified, and control beans (CBs) (regular iron and PA concentrations) was compared in 25 nonpregnant young women with low iron status with the use of a multiple-meal crossover design. Iron absorption was measured with stable iron isotopes.Results: PA concentration in Ipa beans was similar to 10% of BBs and CBs, and iron concentration in BBs was similar to 2- and 1.5-fold compared with CBs and Ipa beans, respectively. Fractional iron absorption from Ipa beans [8.6% (95% CI: 4.8%, 15.5%)], BBs [7.3% (95% CI: 4.0%, 13.4%)], and CBs [8.0% (95% CI: 4.4%, 14.6%)] did not significantly differ. The total amount of iron absorbed from Ipa beans and BBs was 421 mu g (95% CI: 234, 756 mu g) and 431 mu g (95% CI: 237, 786 mu g), respectively, and did not significantly differ, but was >50% higher (P < 0.005) than from CBs (278 mu g; 95% CI: 150, 499 mu g). In our trial, the Ipa beans were hard to cook, and their consumption caused transient adverse digestive side effects in similar to 95% of participants. Gel electrophoresis analysis showed phytohemagglutinin L (PHA-L) residues in cooked Ipa beans.Conclusion: BBs and Ipa beans provided more bioavailable iron than control beans and could reduce dietary iron deficiency. Digestive side effects of Ipa beans were likely caused by PHA-L, but it is unclear to what extent the associated digestive problems reduced iron bioavailability.