Location: Plant, Soil and Nutrition Research
2013 Annual Report
Iron bioavailability studies typically involve isotopic labeling of the food sample in order to track the absorption of the iron. The assumption in this method is that extrinsically added labeled iron mixes and equilibrates fully with the intrinsic Fe of the food sample. If this assumption is accurate, then the iron absorption from the food can be properly monitored. We believe that this assumption has never been adequately tested, even though it has historically been applied to many human iron absorption studies. In the past year we have finished analyzing our results on this project. Overall we find that over the range of concentrations of extrinsically added isotopes that have been used over the past 40-50 years in human studies, incomplete equilibration occurs. The staple crops we have analyzed include various varieties of beans, maize, and lentils. The range of misequilibration can be from 10-300% depending on the crop. This research certainly challenges the accuracy of the multitude of studies on iron bioavailability and absorption. It suggests that we should reconsider the approach for measuring Fe absorption in human subjects. In recent years we have developed a model using fertile chicken eggs as a means to screen compounds for prebiotic activity. Recent studies with this model indicate that arabinose and possibly arabinoxylans isolated from wheat may have prebiotic activity, i.e. the stimulation of growth and proliferation of probiotic or beneficial bacteria such as Bifidobacteria and Lactobacilli. Additional research is continuing to determine the consistency of these effects; however, this observation suggests that wheat breeding efforts to increase arabinoxylan concentrations in the grain should be considered.