ABSTRACT
Objectives: Tef is a cereal indigenous to Ethiopia. The flour obtained is mostly used to produce a soft, pancake-like sourdough-bread, called injera. Since it contains considerable amounts of phytate, iron bioavailability from this Ethiopian staple is believed to be limited. We investigated different strategies to improve iron absorption from tef-injera. These included decreasing the phytate:iron molar ratio by simultaneously enhancing the iron content and lowering the phytate content during fermentation, by the addition of the enzyme phytase and by partially replacing tef by flours exhibiting high phytase activity. Additionally the impact of substituting FeSO4 by the alternative fortificant NaFeEDTA on bioavailability in humans was tested. Methods: Iron absorption was measured with stable isotopes in 2 groups of 17 young women in single-meal studies, serving modified tef-injera meals with tomato sauce in a cross-over design. Results: Iron absorption from traditional tef-injera was low (1.4%) and did not substantially increase with NaFeEDTA but approximately doubled (p<0.01) to 3.6% and 3.1% by reducing the phytate:iron molar ratio from 4.4 to 1.5 and 0.2 in variations with 10% wheat and purified phytase, respectively. Conclusions: Iron absorption was generally low from all meals and fortification of tef-injera with NaFeEDTA did not increase iron bioavailability compared to FeSO4, suggesting other factors, such as proteins or polyphenols, having an additional negative influence. Nevertheless, reducing the phytate content of tef-injera by either co-fortification with wheat or addition of purified phytase more than doubled iron bioavailability from this Ethiopian staple food and would provide additional absorbable iron.