Increasing Micronutrient Bioavailability from Wheat

Lead Research Organisation: King's College London
Department Name: Diabetes & Nutritional Sciences

Abstract

Nutritional deficiency in essential dietary metals such as iron and zinc is a public health concern in the UK, particularly for girls and young women. Approximately 30 - 50% of the iron and zinc in the UK diet is provided by cereals and cereal products (e.g. bread, breakfast cereals and baked goods). However, in wholegrain wheat, most of the iron and zinc is physically contained within a single layer of cells called the aleurone layer. Our recent work shows that aleurone cells are resistant to physical disruption and digestion as they pass along the gastrointestinal tract and are excreted intact in faeces. The aleurone layer is removed during processing of wheat into white flour and hence much of the iron and zinc is lost. While iron is added back into white flour at the milling stage, there is currently no addition of zinc. The aim of this study is to use novel food processing techniques to increase the bioavailability of the naturally-occurring iron and zinc in wheat. This process, called micro-milling, ruptures the aleurone cell walls and potentially makes the iron and zinc more available for absorption. In addition, we will use purified aleurone which has been micro-milled to enrich white flour with iron and zinc. Our recently published work shows that micro-milling increases the solubility of iron and enhances iron absorption by intestinal epithelial cells, and we expect the same to be true for zinc.

The main purpose of our proposal is to build on recently published data and further characterise iron and zinc availability from micro-milled wheat flour. We hypothesize that micro-milling will increase iron and zinc availability from wholegrain flour and from aleurone-enriched white flour. Next, we will carry out human intervention studies to assess iron and zinc bioavailability from bread rolls manufactured from micro-milled wholegrain flour or from white flour enriched with micro-milled aleurone flour. Here we hypothesize that bioavailability of both iron and zinc will be enhanced in foods containing micro-milled flour compared with standard-milled flour. Finally, we will analyse the structure of breads produced using micro-milled wheat flour and assess consumer acceptability of these products in a range of sensory tests. Our hypothesis is that micro-milling will not adversely affect food structure or consumer acceptability. We believe that our research strategy will increase the nutritional quality of food products manufactured from wholegrain wheat, and potentially have health benefits for those at risk of iron and zinc deficiency. Furthermore, our studies might identify micro-milled aleurone as a potential functional food ingredient for use in fortifying or enriching cereal-based products to increase iron and zinc content and bioavailability.

Technical Summary

Approximately 70% of the iron and zinc in wheat is contained within the aleurone cell layer. This layer is highly resistant to food processing, chewing and intestinal digestion, meaning that the bioaccessibility of iron and zinc from these cells is limited. In this proposal we will use micro-milling techniques to rupture the aleurone cell walls with the aim of increasing iron and zinc availability from wheat breads. We have already shown that micro-milling increases the solubility and absorption of iron from wheat flour in vitro.

It is possible to extract and purify aleurone from wheat flour. Our proposal therefore has 2 aims: (i) to ascertain whether micro-milling wholegrain flour increases iron and zinc availability from wholegrain bread; (ii) to determine whether addition of micro-milled purified aleurone flour to white flour increases iron and zinc availability from white bread.

We will take both an in vitro and in vivo approach to address these aims. Our in vitro studies will use a well characterised in vitro digestion protocol, together with measurements of iron and zinc uptake by Caco-2 cells (using ICP-MS). These studies will assess the effect of: (a) different hydrothermal processing methods; (b) the breakdown of phytate; (c) the incorporation of other dietary factors; on iron and zinc availability from breads made from standard milled or micro-milled wheat flour. Next we will carry our human feeding studies to assess the bioavailability of iron (measured using serum iron curves) and zinc (measured using stable isotopes) from breads manufactured from wholegrain flour or from white flour enriched with aleurone flour. Finally, in collaboration with Campden BRI, we will assess the effects of micro-milling on the structure of bread, and measure consumer acceptability of these novel bread products, using a range of quantitative sensory techniques.

Planned Impact

The proposed project will benefit relevant stakeholders beyond the academic community, including the DRINC consortium and the wider commercial sector. Our proposal will address directly the DRINC Research Challenge "Understanding the relationship between food processing and nutrition" and will have impact on the Research Challenge "Designing foods to maintain and improve health". Furthermore, our work is also relevant to the wider BBSRC strategic priorities "Food, nutrition and health" and "Healthy ageing across the life-course".

The proposal focuses on novel food processing techniques to improve iron and zinc bioaccessibility from wheat. Iron and zinc deficiency are recognised as global health problems by the World Health Organisation. In addition, there are public health concerns in the UK regarding the levels of these essential micronutrients in the diets of a number of population groups. Cereals and cereal products are the most important sources of iron and zinc for many individuals in the UK and our multidisciplinary approach will ultimately have impact for consumers through the provision of everyday food products with enhanced iron and zinc bioavailability. There are also clear potential benefits for the food industry, e.g. in the design of novel foods with enhanced nutritional benefit, and through the utilisation of functional food ingredients (e.g. micro-milled aleurone as a bioavailable source of iron and zinc). We anticipate that our research will also have impact for policy-makers when formulating dietary advice and guidelines on iron and zinc bioavailability from cereals and cereal products.

To ensure appropriate dissemination of results for maximum impact, the applicants will have regular meetings with their collaborators to discuss research findings. In addition, we will assemble a project management team that includes external expert advisors to help guide our basic research towards industrial application. A number of the applicants have relevant experience of achieving successful knowledge exchange and commercialisation activities, particularly with the food industry, through collaborative industrial grants, patents, exploitation activities and dissemination events. We will exploit this expertise to provide maximum impact for our work.

Publications

10 25 50
 
Description Campden BRI, Cereals, Milling and Baking Member Interest Group 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Industry/Business
Results and Impact I gave an invited presentation to the Campden BRI, Cereals, Milling and Baking Member Interest Group, formed of food scientists and business leaders within the sector. Approximately 40 people attended the meeting. The purpose of the presentation was to introduce the importance of cereals to iron and zinc nutrition in the UK and globally. Approximately 50% of the iron and 30% of the zinc in the UK diet comes from cereals and cereal products. However the absorption of these minerals is limited by physical encapsulation by plant cell walls and the presence of high levels of anti-nutrient factors such as phytic acid. I briefly described the background to our BBSRC-funded project and outlined the research strategies that we will use to try to improve availability of iron and zinc from cereal-based foods. The question and answer session generated a great deal of discussion. Following the presentation I was asked for further information about our work and the general area of bioavailability of minerals.
Year(s) Of Engagement Activity 2017
 
Description Federation of Bakers Annual Conference 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Third sector organisations
Results and Impact Invited presentation on cereals as a nutritionally important source of minerals, followed by panel Q & A session chaired by a journalist. Potential mechanisms for increasing the release of endogenous minerals from baked products was discussed and compared with current strategies of flour fortification. Feedback from the Federation was positive and reported that members have not previously considered the importance of baked products as a source of minerals. There was an expression of interest in a future presentation based on planned human feeding studies currently underway at King's College London.
Year(s) Of Engagement Activity 2018
 
Description Participation in BBC "Trust Me I'm a Doctor" 
Form Of Engagement Activity A broadcast e.g. TV/radio/film/podcast (other than news/press)
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Public/other audiences
Results and Impact Contributed to a section of the programme discussing and demonstrating iron bioavailability from plant foods - including breakfast cereals and bread. The aim of this section was to increase public understanding of important plant sources of iron and how release and absorption of iron could be maximised by cooking method and by other dietary components. Those interested in this work could find further details on the Trust Me pages on the BBC website
Year(s) Of Engagement Activity 2018
 
Description Presentation at National Association of Britiish and Irish Miller Annual Seminar 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Industry/Business
Results and Impact I gave an invited presentation at the National Association of British and Irish Millers Annual Seminar. Approximately 40 people attended the meeting. The purpose of the presentation was to introduce the importance of cereals to iron and zinc nutrition in the UK and globally. Approximately 50% of the iron and 30% of the zinc in the UK diet comes from cereals and cereal products. However the absorption of these minerals is limited by physical encapsulation by plant cell walls and the presence of high levels of anti-nutrient factors such as phytic acid. I briefly described the background to our BBSRC-funded project and outlined the research strategies that we will use to try to improve availability of iron and zinc from cereal-based foods. The question and answer session generated a great deal of discussion. Following the presentation I was asked for further information about our work and the general area of bioavailability of minerals.
Year(s) Of Engagement Activity 2017
 
Description Presentation at National Association of British and Irish Millers Annual Seminar 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Industry/Business
Results and Impact Dr Mohamad Aslam (postdoctoral researcher on the project) gave an invited presentation at the National Association of British and Irish Millers Annual Seminar. Approximately 40 people attended the meeting. The purpose of the presentation was to give an update on our work on mineral bioavailability from cereals. The question and answer session generated a great deal of discussion and there were several requests for further information about our work and the general area of bioavailability of minerals.
Year(s) Of Engagement Activity 2018
 
Description Presentation at Rank Prize Symposium, March 2019 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Other audiences
Results and Impact Invited speaker at a small research symposium (30 invited attendees) focused on food processing and nutrition. Many of the delegates were early career researchers from UK and International HEI and industry. The symposium closed with a debate on future prospects for processing to increase nutritional value of foods.
Year(s) Of Engagement Activity 2019
 
Description Presentation at the National Institute of Nutrition, India, Centenary Conference 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Invited presentation on cereals as important nutritional sources of minerals as part of the NIN centenary conference " ALIGNING FOOD SYSTEMS FOR HEALTHY DIETS AND IMPROVED NUTRITION". The audience was diverse and included politicians, media, policymakers (e.g. from WHO and FAO) as well as international scientists from industry and academia. The invitation arose from an international collaboration with colleagues from NIN and has increased interest from other groups in India which might potentially lead to further collaborative research and submission of joint grant applications.
Year(s) Of Engagement Activity 2018
 
Description Presentation to British Nutrition Foundation 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Industry/Business
Results and Impact I gave a presentation to approximately 25 members of the joint Industrial Scientists Committee / Scientific Advisory Committee of the British Nutrition Foundation. In the presentation I updated members on the background and rationale for our BBSRC-funded project on mineral availability from cereals and presented some initial results from our project. A question and answer session followed the presentation and in discussions following the presentation I was asked for additional information and invited to produce a paper for publication in the BNF's journal Nutrition Bulletin.
Year(s) Of Engagement Activity 2017
 
Description Workshop, including practical demonstration of the use of micronised flour in the manufacture of baked products 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Industry/Business
Results and Impact We organised a workshop to demonstrate the use of micronised flour in baked goods. The event ran at Campden BRI headquaters in Chipping Campden and there were 20 invited attendees covering SMEs and larger businesses involved in the baking industry. The event included an overview of research taking place at King's College London on food processing, followed by a practical demonstration in the Campden research bakery in which biscuits, cakes and bread were made from standard-milled and micronised flour. Products were available for tasting at the end of the day. The event generated a great deal of interest with requests for futher information and the potential for future collaborations.
Year(s) Of Engagement Activity 2020