The study was designed to test whether low phytic acid beans provide more bioavailable iron than iron biofortified beans in a bean consuming population.
Iron absorption from an lpa, an iron-biofortified, and a control bean with regular iron and phytic acid concentrations was compared in twenty-five non-pregnant women with low iron status by stable iron isotope technique using a multiple meal crossover design.
Fractional iron absorption from the lpa, the biofortified and control bean did not differ and was 8.6% (95%CI: 4.8; 15.5), 7.3% (95%CI: 4.0; 13.4) and 8.0% (95%CI: 4.4; 14.6), respectively. The total amount of iron absorbed from lpa and biofortified bean was 421 µg (95%CI: 189; 611) and 431 µg (95%CI: 222; 737) and did not differ significantly (P=0.12), but was 51% (P<0.005) and 55% (P<0.001) higher, respectively, when compared to the control bean (278 µg). In our trial, the lpa beans caused transient adverse digestive side effects in the participants. Gel electrophoresis analysis showed hemagglutinin residuals in the cooked lpa beans. Subsequent cooking trials with different lpa bean varieties indicated that hemagglutinin stability depended on the genetic background of the beans.
Our results show that biofortified and lpa beans provide more bioavailable iron than normal beans and could thus contribute to a reduction in iron deficiency. Digestive side effects likely were caused by hemagglutinin and it is unclear to what extent this reduced the iron bioavailability from lpa beans. Subsequent cooking trials indicate that lpa beans with different genetic background might be promising for biofortification.