King’s College London Health Schools Studentships 2015 Division: Diabetes & Nutritional Sciences PROJECT DETAILS
Title of project Increasing iron bioavailability from wheat Supervisor 1 Paul Sharp Supervisor 2 Yemisi Latunde‐Dada Project description (max 500 words) Iron deficiency is common in the UK and represents a major burden to the NHS and the UK economy. The National Diet and Nutrition Survey (2012) revealed that up to 30% of the UK female population had low iron stores and a further 10% were anaemic. Low iron status correlated directly with dietary iron intake. 50% of iron in the UK diet is provided by cereals and cereal products. Iron in wheat is largely confined to the aleurone layer, a single layer of cells located between the endosperm and the testa and pericarp. Aleurone is removed as part of the bran component during the production of white flour. For this reason, since 1953 it has been mandatory to add iron (1.65 mg / 100 g flour) to white and brown flours at the mill to restore the iron lost during processing to levels present in wholegrain flour. In the UK, elemental iron powder is used as the main iron source; however, this form of iron has low bioavailability due to its poor solubility. We hypothesize that: (i) disruption of the aleurone layer in wholegrain flour by micro‐milling will increase the bioavailability of endogenous wheat iron; (ii) micro‐milled purified aleurone could provide an alternative source of iron for fortification of white flour. PROGRAMME OF WORK: Year 1. Determine the effects of specialised milling technology on the structure and the chemical composition of wholegrain wheat and purified aleurone. Bühler AG (Switzerland) will provide wheat samples produced by standard‐ and micro‐milling techniques for this project. We will measure the phytic acid content of wheat fractions using a commercially available assay kit. In addition, iron speciation in these fractions will be assessed using HPLC‐based size‐exclusion chromatography coupled to ICP‐MS. Total iron content will be measured using ICP‐OES and soluble iron measured using ferrozine. Year 2. Compare in vitro iron bioaccessibility of wheat fractions produced by standard milling or specialised micro‐milling. Iron bioaccessibility in wheat flour samples will be assessed by measuring ferritin formation in Caco‐2 cells – a surrogate marker of iron absorption. We will investigate the effects of adding food‐grade phytase during cooking, and the effects of enhancers (e.g. ascorbic acid) and inhibitors (e.g. tannic acid) of non‐haem iron absorption on ferritin formation. Year 3. Determine the relative in vitro bioaccessibility of aleurone‐iron vs elemental iron powder when added to white flour. White wheat flour is fortified with elemental iron powder, which has low solubility and bioavailability. We will compare the effects of either standard‐ or micro‐milled aleurone, or elemental iron powder (each added to achieve a final level of 1.65 mg Fe/100 g flour) or iron bioaccessibility measured as Caco‐2 cell ferritin formation. Year 4. Investigate the bioavailability of aleurone‐iron and elemental iron. Iron deficient mice will be fed diet containing 50 mg/Kg iron (an adequate level for mice) either as (a) standard milled aleurone; (b) micro‐milled aleurone; (c) elemental iron. Bioavailability will be measured by changes in serum iron content, transferrin saturation, liver iron content and hepcidin mRNA. Please indicate the type of programme 4 years 1