Speciation and bioavailability of iron in plant foods
Lead Research Organisation:
University of East Anglia
Department Name: Norwich Medical School
Abstract
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Technical Summary
We have selected common classes of plant-based foods that contribute significantly to the UK iron intake and are predicted to contain contrasting chemical forms of iron(cereals, pulses and vegetables). We will investigate the chemical form of iron-complexes in these crops, and the effect of processing and digestion on iron bio-availability and absorption.
To characterize abundant iron species, we will perform whole sample imaging of the plant tissues and of the processed and digested foods, using x-ray fluorescence (xrf) imaging and NanoSIMS. Soluble extracts from raw, processed and digested foods will be frationated by size exclusion chromatography. Iron-rich fractions will be identified by Inductively Coupled Plasma-Mass Spectrometry, and further analysed using advanced spectroscopy techniques (electron paramagnetic resonance, Mössbauer spectroscopy and x-ray based Extended x-ray Absorption Fine Structure). Nanoparticulate (<100 nm) iron will be observed using high resolution Transmission Electron Microscopy.
The bioavailability of different forms of iron will be determined using the Caco-2 cell model. The uptake of iron from digestates will be measured both before and after digestion. Chemical and siRNA-based inhibitory methods will be used to determine the contributions of the three uptake pathways in Caco-2 cells, namely (a) inhibitors of endocytosis, (b) an inhibitor of DMT1 and (c) an inhibitor of Dcyt-B. Endocytosis is the route by which all nanoparticulate (<100 nm) iron accesses the cell, whereas Dcyt-B is required to reduce soluble ferric iron so that it can be transported via DMT1.
The data on the chemical forms of iron in food, effects of processing and digestion, and the bio-availability of Fe, can be used by the food industry to improve nutritional quality of products. Th knowledge on iron speciation and bioavailability will also help in developing improved assays for predicting iron availability, and to state this information on food labels.
To characterize abundant iron species, we will perform whole sample imaging of the plant tissues and of the processed and digested foods, using x-ray fluorescence (xrf) imaging and NanoSIMS. Soluble extracts from raw, processed and digested foods will be frationated by size exclusion chromatography. Iron-rich fractions will be identified by Inductively Coupled Plasma-Mass Spectrometry, and further analysed using advanced spectroscopy techniques (electron paramagnetic resonance, Mössbauer spectroscopy and x-ray based Extended x-ray Absorption Fine Structure). Nanoparticulate (<100 nm) iron will be observed using high resolution Transmission Electron Microscopy.
The bioavailability of different forms of iron will be determined using the Caco-2 cell model. The uptake of iron from digestates will be measured both before and after digestion. Chemical and siRNA-based inhibitory methods will be used to determine the contributions of the three uptake pathways in Caco-2 cells, namely (a) inhibitors of endocytosis, (b) an inhibitor of DMT1 and (c) an inhibitor of Dcyt-B. Endocytosis is the route by which all nanoparticulate (<100 nm) iron accesses the cell, whereas Dcyt-B is required to reduce soluble ferric iron so that it can be transported via DMT1.
The data on the chemical forms of iron in food, effects of processing and digestion, and the bio-availability of Fe, can be used by the food industry to improve nutritional quality of products. Th knowledge on iron speciation and bioavailability will also help in developing improved assays for predicting iron availability, and to state this information on food labels.
Planned Impact
Two billion people worldwide remain iron deficient with iron deficiency anaemia being one of WHO top 10 targets for cure and prevention. Children and women of child-bearing age, particularly pregnant women, have high iron requirements and are at increased risk of iron deficiency anaemia with consequent serious adverse effects on health. Traditionally iron deficiency has been tackled through fortification and supplementation programmes with little success. More recently, biofortification and the nutritional quality of food crops has become an important goal for the agricultural sector. Globally, we have to move to a more sustainable diet, taking into account climate change and nutritional (food) security, and therefore diets will contain lower intakes of meat, especially red meat which has the greatest greenhouse gas effect but which provides iron of the highest bioavailability. Alternative plant food sources, such as cereals and green vegetables, will be of growing importance for supplying iron in the diet. Diets consumed by vegetarians and low-income population groups are particularly low in bioavailable iron.
This project will provide information on the major forms of iron present in plant-based foods and how well they are absorbed by the body. It is anticipated that this will inform strategies for increasing the iron content of foods either by (i) controlling food processing or (ii) manipulating plant-food crops with the ultimate aim to improving the iron status of the UK population.
This project has great potential to bring benefit to (a) the health status of the UK population (b) food regulation and policy (c) UK competitiveness in the field.
(a) The understanding of how iron bioavailability in plant foods can be improved can help to inform plant breeders, growers and the food industry to take steps to ensure improved nutritional quality of their crops and food products produced using plant foods as raw materials. Furthermore, the findings from this project will be disseminated to health professionals (doctors, dieticians, nurses) so that they can offer personalised dietary advice for patients. This will in time help to improve the iron status of the population.
(b) The results of this project can be used for developing better food/nutrition policies for the UK (and internationally) and to develop food based dietary guidelines that ensure that the diet of all population groups meets their requirements.
(c) There are major gaps in our understanding of iron speciation in foods, particularly plant-based foods, and starting to fill these, as we propose, can inform on the development of food-like (and therefore safe) iron food fortificants/supplements and greatly enhance UK competitiveness in the field both academically and industrially.
This project will provide information on the major forms of iron present in plant-based foods and how well they are absorbed by the body. It is anticipated that this will inform strategies for increasing the iron content of foods either by (i) controlling food processing or (ii) manipulating plant-food crops with the ultimate aim to improving the iron status of the UK population.
This project has great potential to bring benefit to (a) the health status of the UK population (b) food regulation and policy (c) UK competitiveness in the field.
(a) The understanding of how iron bioavailability in plant foods can be improved can help to inform plant breeders, growers and the food industry to take steps to ensure improved nutritional quality of their crops and food products produced using plant foods as raw materials. Furthermore, the findings from this project will be disseminated to health professionals (doctors, dieticians, nurses) so that they can offer personalised dietary advice for patients. This will in time help to improve the iron status of the population.
(b) The results of this project can be used for developing better food/nutrition policies for the UK (and internationally) and to develop food based dietary guidelines that ensure that the diet of all population groups meets their requirements.
(c) There are major gaps in our understanding of iron speciation in foods, particularly plant-based foods, and starting to fill these, as we propose, can inform on the development of food-like (and therefore safe) iron food fortificants/supplements and greatly enhance UK competitiveness in the field both academically and industrially.
Publications
Connorton JM
(2017)
Wheat Vacuolar Iron Transporter TaVIT2 Transports Fe and Mn and Is Effective for Biofortification.
in Plant physiology
Moore KL
(2018)
The stage of seed development influences iron bioavailability in pea (Pisum sativum L.).
in Scientific reports
Perfecto A
(2017)
Mechanisms of Iron Uptake from Ferric Phosphate Nanoparticles in Human Intestinal Caco-2 Cells.
in Nutrients
Perfecto A
(2018)
Pea Ferritin Stability under Gastric pH Conditions Determines the Mechanism of Iron Uptake in Caco-2 Cells.
in The Journal of nutrition
Rodriguez-Ramiro I
(2017)
Dietary Factors Modulate Iron Uptake in Caco-2 Cells from an Iron Ingot Used as a Home Fortificant to Prevent Iron Deficiency.
in Nutrients
Rodriguez-Ramiro I
(2019)
Estimation of the iron bioavailability in green vegetables using an in vitro digestion/Caco-2 cell model.
in Food chemistry
Rodriguez-Ramiro I
(2017)
Assessment of iron bioavailability from different bread making processes using an in vitro intestinal cell model.
in Food chemistry
Description | Phytate, a form of phosphorus, binds iron and makes is less well absorbed. We investigated the effect of three commercial baking processes (sourdough, conventional yeast and Chorleywood Bread Making Process (CBP)) on the phytate content of wholemeal bread, its impact on iron uptake in Caco-2 cells and the predicted bioavailability of iron from these breads with added iron, simulating a mixed-meal. The sourdough process fully degraded phytate whilst the CBP and conventional processes reduced it by 75% compared with wholemeal flour. When iron was added to the different breads, only sourdough bread elicited a significant ferritin response in Caco-2 cells (4.8-fold compared to the other breads) suggesting that sourdough bread could help improve iron nutrition. The potential bioavailability of iron in different vegetables was examined and we found that Savoy cabbage was the highest of all tested. The reasons are probably related to the chemical composition and the presence of iron chelators (e.g. fructose compounds) that enhance iron absorption. We also assessed the effects of cooking vegetables in water with the Lucky Iron Fish (LIF, iron ingot promoted for sale in Cambodia to combat iron deficiency) and found a several fold increase in the iron content of intestinal cells (our in vitro model) when exposed to peas that had been cooked in water containing the LIF. This surprising synergy should be further examined with other vegetables, and the reason for the enhanced bioavailability of iron should be sought. |
Exploitation Route | Bakers may change bread baking processes to improve iron bioavailability. Consumers could be advised to select Savoy cabbage as it contains iron that is relatively well absorbed compared with other green vegetables, such as spinach. People at risk of iron deficiency could benefit by cooking vegetables with a Lucky Iron Fish (iron ingot). |
Sectors | Agriculture, Food and Drink,Healthcare |
Description | Our findings relating to iron bioavailability in vegetables were used by the BBC for an episode of Trust me I'm a Doctor. They wanted a quick experiment on iron bioavailability from non-meat sources (in relation to consuming less meat) and used the cell model that we used for the BBSRC project, and the vegetable with the highest iron bioavailability from those we tested (Savoy cabbage). |
First Year Of Impact | 2018 |
Sector | Other |
Impact Types | Societal |
Description | International PhD studentship |
Amount | £100,000 (GBP) |
Organisation | University of East Anglia |
Department | School of Medicine UEA |
Sector | Academic/University |
Country | United Kingdom |
Start | 10/2013 |
End | 09/2016 |
Description | Encapsulation of plant ferritin |
Organisation | University College London |
Department | Research Department of Primary Care & Population Health |
Country | United Kingdom |
Sector | Academic/University |
PI Contribution | We have discussed using the technology owned by Dr Abdul Basit to encapsulate phytoferritin. |
Collaborator Contribution | Dr Basit will be training a PhD student and may carry out encapsulation of phytoferritin if we can obtain the necessary funding. |
Impact | Multi-disciplinary collaboration. Nutrition. Pharmaceutical. |
Start Year | 2017 |
Description | Identification of inositol phosphates (Dr Charles Brearley, UEA) |
Organisation | University of East Anglia |
Department | School of Biological Sciences UEA |
Country | United Kingdom |
Sector | Academic/University |
PI Contribution | We discussed the measurement of inositol phosphates with Dr Brearley as this was an explanatory variable for iron bioavailability.. |
Collaborator Contribution | Dr Brearley measured the inositol phosphate content of various flours and breads, and attended relevant project meetings. |
Impact | Paper (in press) Rodriguez-Ramiro I, Brearley CA, Bruggraber SFA, Perfecto A, Shewry P, Fairweather-Tait S. Assessment of iron bioavailability from different bread making processes using an in vitro intestinal cell model. Food Chemistry 2017. |
Start Year | 2015 |
Description | Attendance at Biioavailability 2018, international conference, Norwich 10-13 Sept 2018 |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Professional Practitioners |
Results and Impact | I gave an invited plenary on Dietary Reference Values which included iron bioavailability, and we presented two posters: 1. Rodriguez-Ramiro I, Dell'Aquila C, Ward J, Bruggraber SFA, Shewry PR, Fairweather-Tait S. Estimation of the iron bioavailability in green vegetables using an in model.vitro digestion/Caco-2 cell model. 2. Connorton JM, Jones ER, Rodriguez-Ramiro I, Fairweather-Tait S, Uauy C, Balk J. changing expression of a vacuolar iron transporter doubles the iron content of wheat flour. |
Year(s) Of Engagement Activity | 2018 |
Description | Helped BBC with Trust me I'm a Doctor program Series 8 Episode 2 |
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 | I helped the BBC make an episode for Trust me a Doctor. I couldn't host the lab work at UEA so suggested they asked Paul Sharp at King's College. They tested vegetables that we had been working on, notably Savoy cabbage. My name was in the acknowledgements, and I received the following email from them, with a link to the program: Hello, I hope this email finds you well. Please see link below to the programme you helped us make, Trust Me, I'm a Doctor Series 8 Episode 2. We just wanted to thank you again for your involvement in making this programme - and we hope you enjoy watching it again! https://www.dropbox.com/sh/6ebto919jx1irdi/AAByzUzxz35FFDhBGvBLFhfxa?dl=0 Best wishes, Trust Me I'm A Doctor Team |
Year(s) Of Engagement Activity | 2018 |