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

Petry N, Rohner F, Gahutu JB, Campion B, Boy E, Tugirimana PL, Zimmerman MB, Zwahlen C, Wirth JP, and Moretti D.

March 2016 – Journal of Nutrition

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. As low-phytic acid (lpa) bean varieties could increase iron bioavailability, we tested whether lpa beans provide more bioavailable iron than a BBs and control beans (CBs) (regular iron and PA concentrations) by comparing iron absorption 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. The total amount of iron absorbed from lpa beans and BBs was 421 μg (95% CI: 234, 756 μg) and 431 μg (95% CI: 237, 786 μg), respectively, and did not significantly differ, but was >50% higher (P < 0.005) than from CBs (278 μg; 95% CI: 150, 499 μg). In our trial, the lpa beans were hard to cook, and their consumption caused transient adverse digestive side effects in ∼95% of participants. Gel electrophoresis analysis showed phytohemagglutinin L (PHA-L) residues in cooked lpa beans. In conclusion, BBs and lpa beans provided more bioavailable iron than control beans and could reduce dietary iron deficiency. Digestive side effects of lpa beans were likely caused by PHA-L, but it is unclear to what extent the associated digestive problems reduced iron bioavailability.