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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

2011 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 2011, we continued the development and use and development of a poultry model that can be used to determine iron bioavailability from foods. This model was utilized to demonstrate the nutritional benefits of feeding high Fe lentils, and thus providing strong preliminary data to warrant pursuing these studies in humans. Planning a human efficacy trial in Bangladesh is now underway, and we will be a part of that effort, presumably by testing the samples that will be candidates for the human trial.

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 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. Our initial results from this work indicate that extrinsic labels do not equilibrate adequately with crops such as colored beans. Corn, lentils and white beans show better equilibration but still less than complete. Additional testing is planned for these crops in the coming year.

Iron deficient people tend to eat a multitude of substances and products such as chalk, charcoal, clay, soil, rice kernels, etc. Iron concentration and bioavailability in these samples has never been adequately tested. In collaboration with Cornell faculty in the Division of Nutrition we have begun testing these samples to see if they are potential sources of Fe and or inhibitors of Fe absorption and thus exacerbating the condition. Initial results indicate that Fe concentrations vary widely and that some substances are extremely high if Fe concentration. Testing for Fe bioavailability will be done in the coming year, focusing primarily on the Fe bioavailability from clay soil samples.

Transgenic colored bean samples engineered to be low in phytic acid (an iron absorption inhibitor) were received and analyzed for Fe bioavailability from collaborators at Pavia University in Italy. The initial results are promising and indicate that on a small scale basis low phytate beans can be produced with no loss in plant yield, and increased Fe bioavailability. Animal trials are now planned for these crops once harvest is complete in late summer of this year.

Progress was monitored by monthly meetings in addition to phone calls, emails and/or conference calls as needed.


Last Modified: 4/18/2014
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