The Role of Plant Cell Walls in Regulating Starch and Lipid Bioaccessibility from Plant Foods: In Silico In Vitro and In Vivo Studies

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

Abstract

Most people commonly eat plant foods rich in starch, notably cereal products (e.g. bread, rice), and also some that are rich in fat (e.g. tree nuts). However, little is known about how such foods release starch and fat in the human gut and how, in turn, this may influence digestion and ultimately the absorption of nutrients into the body. Improving our understanding of these processes is important for basic scientists studying the behaviour of foods in the gut and their effects on metabolism. It is also important for health professionals and policy makers that are worried about excessive food consumption and the growing problem of obesity and associated problems of heart disease and diabetes. Moreover, the rate and extent of starch and fat digestion and absorption into the blood stream are important factors in altering the risk of heart disease. The release of fat and starch from plant foods and the digestion and absorption of these nutrients by the body are highly complex processes. Our progress in understanding these processes is impeded by the hugely complex structure and properties of plant foods and individual nutrients. Our project proposal brings together a unique combination of world experts from different institutions and disciplines. These experts have formed a large team in order to improve our knowledge of how edible plants behave in the gut and how the gut reacts to the starch and fat available for digestion. For example, it is important to know about the rate at which nutrients are released from plant foods as they move along the gut, since this will affect the time course of digestion and absorption. This in turn will influence the way the nutrients are metabolised within the body. We currently study almond nuts and cereals, e.g. wheat, to see how fat and starch are released from plant tissues. Starch, fat and other nutrients are found inside numerous cells that make up the plant tissue, e.g. an almond seed contains about 50 million cells. Such cells are very small in size, often with a diameter of less than about one tenth of a mm. One significant factor that seems to affect nutrient release from plant cells is the presence of cell walls, more commonly referred to in nutrition as 'dietary fibre'. How starch and fat are released from these cells is poorly understood. Initial studies will involve examining the role of cell walls as physical barriers in controlling the release and digestion of nutrients, using various methods to examine plant tissue at a cellular scale. One novel method will be the use of a recently established 'Dynamic Gastric Model', a computer-controlled simulation of digestion in the human stomach. We will also feed human volunteers with the same plant foods rich in fat and starch, to determine the effects of processing and mastication on nutrient release and digestion and the rate at which digested nutrients are transported into the blood stream. Finally, we will also produce a mathematical description of how fat and starch are released from edible plant tissues during digestion. It is envisaged that in the future, the use of mathematics will allow research scientists to predict the behaviour of similar foods in the gut without having to do so many laboratory experiments. This work will help the food industry to produce new food products or ingredients that have a controlled release of starch and fat in the gut, which could, for example, help to reduce the risk of heart disease. Indeed, Premier Foods, a large food manufacturer, has agreed to collaborate with us and provide scientific and technological expertise. Premier Foods has also agreed to provide cereals (e.g. wheat) and food products made with these cereals, all of which have been specially prepared to control starch release. These raw materials and food products will be used in our project to study how they behave in the gut and assess their potential benefits in reducing the risk of heart disease.

Technical Summary

The release ('bioaccessibility') of starch and lipid from plant foods in the gut plays an important role in influencing starch and lipid digestion, postprandial metabolism and gut hormone signalling. However, the mechanisms of nutrient release from plant food matrices are largely unexplored. Moreover, there have been no fundamental studies on the role of plant cell walls (PCW) in influencing nutrient release. The aim of this project is to understand how PCW ('dietary fibre') of exemplar foods (almonds and wheat) influence the bioaccessibility and digestion of intra-cellular starch and lipid and consequential effects on postprandial metabolism in humans. A multidisciplinary approach will be used, involving a novel combination of in silico, in vitro and in vivo methods to study starch and lipid bioaccessibility, digestion kinetics and postprandial metabolism. A mathematical model will be developed for predicting nutrient release from plant tissues using geometric theory and empirical data from microstructural analysis of plant materials and digestion studies. Model gut simulations of digestion will be used to study the effects of processing, mastication and gut environment on starch and lipid release and the role of PLW. Kinetic experiments on separated plant cells will be conducted to determine if amylase and lipase penetrates PCW and hydrolyses intra-cellular starch and lipid, respectively. In human studies, the effects of chewing and digestion on lipid release will be determined. Effluent from ileostomists will be used to quantify starch and lipid loss at the terminal ileum and examine 'digested' plant tissue microstructure. In human metabolic studies, we will also determine the effects of lipid and starch release on postprandial glycaemia, insulinaemia, lipaemia, and gut peptides GIP, GLP-1 and CCK. These studies will provide basic information to support the design of foods with starch and lipid absorption profiles beneficial to cardiovascular ageing.

Planned Impact

The proposed research will be beneficial to relevant stakeholders outside the academic communities, including the commercial sector, public sector bodies (e.g. FSA) and the general public. Our work will be particularly useful to food companies and may lead to innovative applications in the future, such as the engineering of 'functional ingredients and foods'. The design of foods made from raw ingredients with controlled and predictable nutrient release would benefit public health. The main beneficieries will be the DRINC members and Premier Foods (PF), our industrial partner. PF claim that our research work could potentially lead to the use of raw ingredients (e.g. cereals) in snack and bakery products with predictable nutritional properties. PF could also benefit from the use of the bioaccessibility and digestion models, which have potential use in the screening of raw ingredients, especially for novel products with a health claim. One advantage with using such models is that they reduce the number of expensive human studies. This would be of considerable value to PF in view of its interest in improving consumer health and the development of health claims under EU regulations. The research also has potential impact on DRINC members using raw ingredients for producing nutritionally-enhanced cereal products or products containing other edible plants. The research should also help policy-makers in formulating new dietary advice and guidelines from new data on plant foods. The applicants regularly give talks at schools and media interviews about their research. The applicants will interact with members of DRINC by having regular meetings to discuss on-going research during the project. There will also be regular meetings between the academics and the team at PF to discuss research findings. This will build on existing contacts with PF, since the applicants already collaborate on studies of whole grain cereals. To optimise interaction with PF, the research staff and PhD student on the project will spend time working at PF's research centres in Lichfield (Holgran) and High Wycombe (Premier Analytical Services). The academic centres have websites providing information on research projects; KCL has College School and Divisional websites, which are regularly updated by designated staff. The applicants will take steps to ensure that outcomes are highlighted along with publicity about publications arising from the research work. The research centres also have public relations departments dealing with media publicity. For the DRINC, a BBSRC external co-ordinator will monitor the progress of the project and also facilitate networking between the applicants and industry. The existing collaboration between the applicants and PF will continue throughout the period of the grant. PF have agreed to provide in-kind support for technological expertise and assistance for milling of cereal endosperm, characterising endosperm microstructure as well as provision of cereal-based products. One of PF's partners, Bühler AG, will collaborate on the milling of cereals. The consortium of food companies in DRINC will be offered first-market access to intellectual property if the results of the research lead to industrial applications. PF would also wish to explore potential future industrial applications. All the academic centres have mechanisms in place for exploring industrial applications; at KCL, King's College London Business (KCLB) is the main body for dealing with exploitation of academic research in industry. The applicants, research staff and PhD student will all play some role in undertaking impact activities. Many of the applicants have relevant experience for achieving successful knowledge exchange and impact with the beneficiaries. The applicants have a long history of collaborating with industry, particularly food companies, as evidenced by their successful record of obtaining industrial grants and the publication of patents.

Publications

10 25 50
 
Description The mathematical models we have developed can now be used for predicting nutrition-relevant properties of raw ingredients. The lipid release model can be applied to foods other than almonds, which also have spherical cells, and this is something that is being pursued. This could be useful to industry for predicting lipid release of different mill fractions for different foods. The Logarithm of Slope (LOS) plots have been used on food ingredients (wheat and chickpea particles of different sizes) and foods to predict the extent of starch digestion accurately from starch digestibility curves. These predictions may allow producers of raw ingredients to make small adjustments to their products, which when incorporated into everyday food products could potentially significantly improve public health. This includes reduced risk factors associated with type 2 diabetes and heart disease and also beneficial effects on body weight maintenance. For instance, our results highlight the importance of the physical structure of plant cell walls ('dietary fibre'), in determining the rate and extent of starch/fat digestion and absorption. This has an important bearing for example on determining the blood glucose and insulin responses after starchy meals. The results may lead to the development of novel ingredients and functional foods with enhanced nutritional properties.
Exploitation Route We have had discussions with a number of food companies about possible applications of our work on starch digestion and postprandial glycaemia, and also lipid release prediction. Local practising dieticians have been made aware of our research, which strengthens their ability to provide evidence-based care to NHS patients. Presenting our results at many national and international conferences and publicising our open access publications via social media (Twitter, Research Gate, and linkedin) and TV (BBC 1, 'Britain's Favourite Supermarket Foods', 25th July 2013 - Episode 2) means that our results have been highlighted to both academic and non-academic audiences, and are accessible. We are developing collaborations with the food industry to commercialise some of the ideas that have arisen out of this project - this has been funded by Pathfinder, Follow-on and Super Follow-on awards. As a result of further funding by the BBSRC (Pathfinder, Follow-on and Super Follow-on) progress has led to IP (patent) for the development of a novel legume ingredient for use in food products (e.g. cereal products) and meetings (2018-20) have taken pace between researchers and commercialise the new ingredient and to use it in the development of food products with enhanced nutritional properties.
Sectors Agriculture, Food and Drink,Healthcare,Manufacturing, including Industrial Biotechology,Pharmaceuticals and Medical Biotechnology

 
Description Our published research, as indicated in a large number of research publications, shows promise in having economic and societal impact (i.e. emerging impact). For example, our research findings generated from this project has led to further successful BBSRC applications (Pathfinder, Follow-on and Super Follow-on grants). These projects were designed to explore and evaluate the commercial opportunities of a novel functional food ingredient with enhanced nutritional properties that can be used in a range of functional foods (e.g. staple foods such as bread, breakfast cereals). Such a food ingredient may lead to food products that are of benefit to human health, especially in relation to risk factors associated with cardiometabolic disorders (e.g. in the prevention and management of type 2 diabetes). Meetings have been held during 2018-20 between the researchers and the food industry to investigate potential food products that could be produced with the new ingredients (e.g. cereal product sector); this activity has continued through additional BBSRC funding mentioned above to explore what products could be developed with food industry.
First Year Of Impact 2014
Sector Agriculture, Food and Drink,Healthcare,Manufacturing, including Industrial Biotechology,Pharmaceuticals and Medical Biotechnology
Impact Types Societal,Economic

 
Description BBSRC Follow-On grant
Amount £203,000 (GBP)
Funding ID BB/M021076/1 
Organisation Biotechnology and Biological Sciences Research Council (BBSRC) 
Sector Public
Country United Kingdom
Start 05/2015 
End 05/2016
 
Description BBSRC IAA
Amount £10,000 (GBP)
Funding ID BB/S506679/1 
Organisation Biotechnology and Biological Sciences Research Council (BBSRC) 
Sector Public
Country United Kingdom
Start 01/2019 
End 04/2019
 
Description BBSRC Pathfinder Award
Amount £10,894 (GBP)
Funding ID BB/M005593/1 
Organisation Biotechnology and Biological Sciences Research Council (BBSRC) 
Sector Public
Country United Kingdom
Start 07/2014 
End 08/2014
 
Description Biochemical Society Travel Grant
Amount £350 (GBP)
Organisation Biochemical Society 
Sector Charity/Non Profit
Country United Kingdom
Start 07/2012 
End 07/2012
 
Description QIB PoC Fund
Amount £9,278 (GBP)
Organisation Quadram Institute Bioscience 
Sector Academic/University
Country United Kingdom
Start 03/2019 
End 06/2019
 
Description Short Term Scientific Missions (STSM)
Amount € 2,500 (EUR)
Organisation European Commission 
Department Seventh Framework Programme (FP7)
Sector Public
Country European Union (EU)
Start 10/2013 
End 11/2013
 
Description Super Follow On
Amount £948,864 (GBP)
Funding ID BB/P023770/1 
Organisation Biotechnology and Biological Sciences Research Council (BBSRC) 
Sector Public
Country United Kingdom
Start 05/2018 
End 05/2020
 
Title HP 
Description A biochemical assay for studying alpha-amylase action on starch involves a novel method for the analysing digestibility curves using first-order enzyme kinetics. This method of analysis, referred to as Logarithm of Slope (LOS), can be used to identify and quantify nutritionally important starch fractions, including starches that are resistant to amylolysis, i.e. resistant starch (RS). This assay and method of analysis has considerable use in studying the molecular mechanisms of amylase action on RS and may also be useful as a screening method for evaluating the digestibility of starches in vivo and their impact on postprandial glycaemia in human subjects. 
Type Of Material Model of mechanisms or symptoms - in vitro 
Year Produced 2013 
Provided To Others? Yes  
Impact This in vitro digestibility assay coupled with LOS plot analysis has considerable use as research tool in studying the molecular mechanisms of amylase action on RS. This approach is also likely to be useful as a screening method for evaluating the digestibility of native and hydrothermally-processed starches in vivo and their impact on postprandial glycaemia in human subjects. 
 
Title LOS Plots 
Description The data analysis method takes a standard starch digestibility plot for starch or food materials, from which the logarithm of the slope of the digestibility plot is calculated. This can then be plotted to give the key enzyme kinetic parameters, k, and C-infinity. k refers to the rate of reaction, whereas C-infinity refers to the extent of the reaction. The plots can also detect changes in the rate of reaction. The model was first published in 2012 (10.1016/j.carbpol.2011.10.048) showing its use on native and gelatinised starches, and has since been used in 2 papers from our group looking at retrograded starches and food particles. 
Type Of Material Data analysis technique 
Year Produced 2012 
Provided To Others? Yes  
Impact The paper has been cited 16 times in 2 years. The method has advantages over the traditional Englyst method of defining starch digestibility. 
 
Title Lipid release model 
Description This model allows the prediction of lipid release from plant foods which have (pseudo)spherical cells. The parameters required are an accurate cell diameter (using stereological principles from micrograph measurements) and particle size. It can be used to predict lipid release from distributions of particle sizes. Related publications: DOI: 10.3945/ajcn.114.088328 , DOI: 10.1039/C4FO00659C , DOI: 10.1017/S0007114514002414 . 
Type Of Material Data analysis technique 
Year Produced 2014 
Provided To Others? Yes  
Impact Impact is yet to be realised, but there is interest from the food industry to make use of this novel method 
 
Description Almond cell wall permeability to digestive agents 
Organisation National Center for Scientific Research (Centre National de la Recherche Scientifique CNRS)
Department Centre National de la Recherche Scientifique Marseille
Country France 
Sector Academic/University 
PI Contribution Provision of materials and labour for the experiments. Acquisition of grant funding to make visit possible.
Collaborator Contribution Provision of materials, facilities and expertise to determine almond cell wall permeability to digestive agents.
Impact Outputs yet to be realised.
Start Year 2013
 
Description CE Development and characterisation of a functional food ingredient 
Organisation New-Food Innovation Ltd
Country United Kingdom 
Sector Private 
PI Contribution Physical and chemical characterisation of the functional food ingredient.
Collaborator Contribution New-Food Innovation Ltd (NFI) were involved in developing the technology for processing the functional food ingredient and were also involved in evaluating the safety of the product (e.g. microbiological assessment).
Impact A novel food ingredient with enhanced nutritional properties has been produced using commercial food processing technology.
Start Year 2015
 
Description Cell wall composition using antibody microarrays 
Organisation University of Copenhagen
Country Denmark 
Sector Academic/University 
PI Contribution Samples of raw, cooked and processed plant foods were supplied to University of Copenhagen for analysis.
Collaborator Contribution Cell wall composition was investigated using a novel technique developed using antibodies to detect specific cell wall polysaccharides after extraction by CDTA and Sodium hydroxide.
Impact Interesting data which has not yet been published.
Start Year 2011
 
Description DSC access 
Organisation University College London
Country United Kingdom 
Sector Academic/University 
PI Contribution Provision of samples for testing, intellectual input and labour.
Collaborator Contribution Intellectual input, and provision of facilities.
Impact Future publications.
Start Year 2013
 
Description Milling of materials 
Organisation Satake Corporation UK Division
Country United Kingdom 
Sector Private 
PI Contribution Provision of starting materials and some labour for production.
Collaborator Contribution Provision of facilities and expertise (and some labour) to produce milled materials.
Impact Many outcomes from the project have resulted due to the production of the milled materials, particularly publications and conference presentations.
Start Year 2010
 
Description Milling of materials 
Organisation University of Manchester
Country United Kingdom 
Sector Academic/University 
PI Contribution Provision of starting materials and some labour for production.
Collaborator Contribution Provision of facilities and expertise (and some labour) to produce milled materials.
Impact Many outcomes from the project have resulted due to the production of the milled materials, particularly publications and conference presentations.
Start Year 2010
 
Description Particle shape and size of chewed almonds 
Organisation Malvern Instruments
Country United Kingdom 
Sector Private 
PI Contribution Provision of samples and methodology for preparing samples for particle size measurement.
Collaborator Contribution Malvern provided guidance on the correct settings to use for their Mastersizer 2000. Sympatec measured particle size, shape and number using their QICPIC instrument.
Impact Data from the Malvern Mastersizer 2000 was used in a publication (DOI: 10.3945/ajcn.114.088328 ). Future publications will include data from this instrument.
Start Year 2010
 
Description Particle shape and size of chewed almonds 
Organisation Sympatec
Country Germany 
Sector Private 
PI Contribution Provision of samples and methodology for preparing samples for particle size measurement.
Collaborator Contribution Malvern provided guidance on the correct settings to use for their Mastersizer 2000. Sympatec measured particle size, shape and number using their QICPIC instrument.
Impact Data from the Malvern Mastersizer 2000 was used in a publication (DOI: 10.3945/ajcn.114.088328 ). Future publications will include data from this instrument.
Start Year 2010
 
Description Postprandial responses 
Organisation Imperial College London
Department Department of Medicine
Country United Kingdom 
Sector Academic/University 
PI Contribution The research team provided a novel material and intellectual input regarding the properties of this material and also provided gut hormone analysis kits which added value to interpretation of collaborative research findings.
Collaborator Contribution ICL collaborators included the novel material in a 3-meal randomized cross-over acute postprandial study in healthy subjects and collected samples for analysis of glucose, insulin and gut hormones. QIB provided expertise and specialist analysis of the test meals used (with and without novel material) in terms of starch digestibility and micro structure.
Impact Multidisciplinary collaboration: Disciplines of physiology and clinical nutrition/dietetics provided by collaborator; Biochemistry and food science provided by researchers at KCL and QIB.
Start Year 2016
 
Description Postprandial responses 
Organisation Quadram Institute Bioscience
Department Food & Health Programme
Country United Kingdom 
Sector Academic/University 
PI Contribution The research team provided a novel material and intellectual input regarding the properties of this material and also provided gut hormone analysis kits which added value to interpretation of collaborative research findings.
Collaborator Contribution ICL collaborators included the novel material in a 3-meal randomized cross-over acute postprandial study in healthy subjects and collected samples for analysis of glucose, insulin and gut hormones. QIB provided expertise and specialist analysis of the test meals used (with and without novel material) in terms of starch digestibility and micro structure.
Impact Multidisciplinary collaboration: Disciplines of physiology and clinical nutrition/dietetics provided by collaborator; Biochemistry and food science provided by researchers at KCL and QIB.
Start Year 2016
 
Description Starting materials 
Organisation Almond Board of California
Country United States 
Sector Private 
PI Contribution Intellectual input.
Collaborator Contribution Supply of starting materials for project.
Impact All outputs related to the project were dependent on starting materials.
Start Year 2010
 
Description Starting materials 
Organisation Millbo
Country Italy 
Sector Private 
PI Contribution Intellectual input.
Collaborator Contribution Supply of starting materials for project.
Impact All outputs related to the project were dependent on starting materials.
Start Year 2010
 
Description Starting materials 
Organisation Proudman Oceanographic Laboratory
Country United Kingdom 
Sector Academic/University 
PI Contribution Intellectual input.
Collaborator Contribution Supply of starting materials for project.
Impact All outputs related to the project were dependent on starting materials.
Start Year 2010
 
Title MEDIUM/LOW GLYCAEMIC INDEX PRODUCTS AND METHODS 
Description The invention relates to a process comprising (a) providing a quantity of plant material; (b) heating the material of (a) in aqueous medium to a temperature of 75 to 105 ºC; (c) physically disrupting the material of (b); (d) processing the physically disrupted material of (c) to enrich for cells and/or cell clusters; and (e) drying the material of (d). The invention also relates to a product, which comprises at least 30% or more intact plant cells, which comprises 15% or less water by weight, which has a particle size in the range 75 - 500 µm, characterised in that the product comprises at least 30% resistant starch as a proportion of total starch. The invention also relates to foodstuffs. 
IP Reference WO2019155190 
Protection Patent application published
Year Protection Granted 2019
Licensed No
Impact It is still too early to report on any impact, but progress has been made in identifying potential food products that could be developed using the novel legume powder ingredient.
 
Description Carbohydrate Quality (Texcoco) 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Postgraduate students
Results and Impact This activity was intended to raise awareness of nutritional assessment and quality of carbohydrates, and encourage interactions between breeders, food processing experts and nutritionists/clinicians to achieve healthier carbohydrate foods. Mainly the audience was from CIMMYT and many were unaware of some of the key concepts presented. This stimulated discussion and requests for further information and guidance regarding methods of carbohydrate quality assessment.
Year(s) Of Engagement Activity 2017
 
Description Food Industry 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Industry/Business
Results and Impact Discussion about research findings to audience of food industry members, which has led to continued discussions about possible applications of new functional food ingredients in the area of food structure and health. especially the role of oat beta-glucan.
Year(s) Of Engagement Activity 2018,2019,2020
 
Description PB gave a lecture on enzymology related to starch digestion and implications to health 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? Yes
Geographic Reach Regional
Primary Audience Schools
Results and Impact Generated a lively discussion about the research activities of our research group and other activities at KCL

None
Year(s) Of Engagement Activity 2013
 
Description Presentation at Food Matters Live 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Industry/Business
Results and Impact Presented application of research findings to a mixed audience of approximately 30 people. This stimulated questions and discussion with knowledge exchanged between audience members from different background.
Year(s) Of Engagement Activity 2016
 
Description Special Interest Group 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Undergraduate students
Results and Impact Discussion with nutritionists and dieticians (attendance, ~50) about the importance of food structure, including oats and behaviour of soluble dietary fibre, in influencing gut health, metabolism and health benefits.
Year(s) Of Engagement Activity 2017,2018,2019,2020
 
Description Youtube video on nutrient release from legumes 
Form Of Engagement Activity A broadcast e.g. TV/radio/film/podcast (other than news/press)
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Public/other audiences
Results and Impact Youtube video describing the importance and nutritional potential of legumes. 142 views and 8 likes so far.
Year(s) Of Engagement Activity 2018
URL https://www.youtube.com/watch?v=0J2gwKw5tkY