A Multiple Meal Study to Evaluate the Role of Phytic Acid From Beans on Human Iron Absorption

Iron deficiency and iron deficiency anemia are among the major health problems in the developing world. Women of childbearing age as well as children are the most vulnerable population groups. In Rwanda, more than 40% of the population is estimated to be anemic. A promising approach to combat iron deficiency in Rwanda is biofortification of beans. The average consumption of beans is about 150 g per person per day in Rwanda and beans are a major staple food. Traditional plant breeding has increased the iron content of certain bean varieties from about 5 to 11 mg/100g. Iron absorption from beans however is with about 2-3% low because of high phytate and high polyphenol contents. A recently conducted study in Rwanda showed that the total amount of iron absorbed from a biofortified high iron bean was similar to the amount of iron absorbed from a control bean, which had a 50% lower iron concentration. This was surprising since the subjects had a low iron status and where therefore expected to maximize iron absorption. However, it was concluded that the additional iron bred into the bean was not bioavailable most likely due to the strong inhibitory nature of phytate in the high iron bean. To clarify that, a multiple meal study (iron absorption study) in collaboration of the Human Nutrition Laboratory of ETH Zurich and the Medical Faculty of the National University of Rwanda is planned. Subjects will receive two different bean varieties (normal iron vs. high iron) in combination with other food ingredients typical for that region. The bean varieties will be served with native phytate concentration, partially dephytinized (50%) or totally dephytinized.

Subjects will be apparently healthy females of reproductive age (18-30y). Iron absorption will be determined by stable isotope techniques.