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United States Department of Agriculture

Agricultural Research Service

Research Project: Improving the Iron Bioavailability from Staple Food Crops, Food Products, and Food Ingredients

Location: Plant, Soil and Nutrition Research

2013 Annual Report


1a.Objectives (from AD-416):
Study food factors and intestinal conditions that enhance and inhibit the bioavailability of iron in staple food crops, food products and food ingredients.


1b.Approach (from AD-416):
Use a combination of in vitro assays and animal studies to identify factors that enhance or inhibit iron bioavailability from foods. We will also employ sophisticated state of the art analytical techniques to measure and profile the minerals and phytochemcals in the foods. We will also use techniques that profile the microflora of the intestine to determine how intestinal bacteria influence iron bioavailability. Coupled together, this combination of in vitro techniques, animal trials and analytical methods will expose the mechanisms of how various food and intestinal factors influence iron bioavailability.


3.Progress Report:

In FY 2013, we continued the use of a simulated digestion/intestinal cell culture model and poultry model for Fe bioavailability from foods. In the past year, these models were utilized to investigate the potential nutritional benefits of feeding high Fe beans. Specifically, we investigated high Fe and low Fe red mottled beans (targeted for release in Rwanda). If our results agree with the human studies, then we have validated our ability to predict efficacy of these samples. These tools can then be used to develop lines of staple food crops, monitor lines already released, and in the process make research funds more cost-effective. For the red mottled beans in Rwanda, our model predicts that the high Fe beans will provide increased nutritional benefit. The preliminary analysis of the human data indicates the same.

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.


Last Modified: 12/17/2014
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