The Mouth - Gut - Brain Model

Lead Research Organisation: University of Reading
Department Name: Food and Nutritional Sciences

Abstract

Obesity and associated conditions such as type 2 diabetes and cardiovascular disease are major global health concerns. A contributing factor is overconsumption of energy dense foods, rich in fat and sugar, driven by our hedonic and physiological desire to consume energy rich foods. One approach has been to reduce the energy content of foods whilst retaining the sensorial quality. The food industry has developed a wide range of healthier products. In order for these products to be successful, consumers must continue to purchase and consume them. However, recent studies have suggested that reducing the energy content of a food may have unintended consequences. Specifically, if a food looks, and tastes like it is rich in nutrients, the gut and brain systems prepare to expect a high energy intake. If this does not happen, as in the case of a reduced calorie food, the brain appears to induce hunger signals that drive the individual to overconsume at subsequent meals (rebound hunger), resulting in an increased calorie intake, thus negating the whole effect of consuming the reduced calorie food. This leads to consumer dissatisfaction with these products, and potentially to imbalances in appetite and hunger hormones that often cause rapid weight gain following periods of dieting.
Therefore we need to rethink how reduced calorie foods can be used more effectively to control energy intake. To do this, we need to understand the relationship between how we sense foods, how we digest and absorb the nutrients and how the brain responds to these processes and controls subsequent appetite signalling. This Mouth-Gut-Brain system is key to controlling our appetite and energy intake.

The aim of this project is to understand how the mismatch between sensory properties and nutrient intake of food controls our appetite and rebound hunger. The key question we aim to address is, by how much can the energy content of a food be reduced before rebound hunger and overconsumption occurs? The key impact will be our ability to modify reformulated foods to reduce the gap between sensory and nutrient signals in order for reduced-energy alternatives to satisfying and not result in subsequent over-consumption.
This project will focus on fat, as fat has the highest energy content, and the sensory properties of low fat foods are challenging for both consumers and the food industry. We will investigate the impact of reducing the fat content of foods by determining how the sensory properties control consumer expectations of satiety (feeling of "fullness"), and measure how much we can reduce fat content before consumers develop rebound hunger and overconsume at a subsequent meal.
Using this information we will design a more realistic food where the structure, physical behaviour and sensory properties are closely matched, but with a range of fat contents and fat type, to carefully control how much fat is "sensed" and how much is absorbed. We will measure how the appetite response of these foods controls the consumption of food in a following meal; and study differences between individuals who are sensitive or insensitive to fat content in foods. This will determine how much we can alter the sensory and fat content of food and still maintain an overall reduction in energy across subsequent meals.
Results will provide valuable information on how mouth-gut-brain signalling fundamentally controls appetite, and begin to unravel why different individuals may be more susceptible to rebound hunger following the consumption of reduced calorie foods. The research will also enable us to define a broader research programme to investigate mouth-gut-brain interface that will study in more detail variations between individual responses, and the biological mechanisms behind our behavioural measures (such as gut hormone levels).
Knowledge generated will enable better approaches to reduced calorie foods that are more effective at reducing energy intake in the longer term.

Technical Summary

There is emerging evidence that reduced energy foods with a high sensory quality have limited effectiveness at reducing long term energy intake and weight management. This is thought to be due to the disparity between the sensory expectation of energy content / satiety and the actual physiological nutrient / energy uptake. This disparity in mouth-gut-brain signalling has been shown to result in rebound hunger and overcompensation of energy intake at subsequent meals. This study aims to combine sensory science, food structure and materials, consumer psychology and behaviour to determine the mechanisms that underpin this disparity and to determine the level by which the organoleptic properties and nutrient content can be altered to avoid rebound hunger and overcompensation of energy intake.
Initial experiments will measure the tolerance for fat reduction in a model food between sensory attributes and expected satiety; and determine the mouth-gut discordance by measuring subsequent appetite response. These results will inform the rational design of realistic foods, using the interfacial and colloidal properties of the emulsions and biopolymer microgels to closely match physical and sensory properties but with reduced fat content. The in vitro release and digestion of fat from the matrix will be used to finely control the difference between sensory expectation and actual nutrient delivery. Further human studies will determine the impact of controlled fat reduction on rebound hunger and overcompensation; both in individuals who are hypo- and hyper-sensitive to fat perception.
The outputs will inform the design of future projects to unravel the role of gut hormone signalling, as well as phenotypic /genotypic effects in consumer behaviour toward low energy foods. This will provide nutritionists, academics and the food industry with tools to develop effective dietary and weight management strategies to help combat of obesity, type 2 diabetes and cardiovascular disease.

Planned Impact

We envisage the main long term vision for this work will be a programme of research projects aiming to improve the repeat consumption of healthier foods by rational design of foods with a defined relationship between the sensory perception, nutritional delivery, and psychological response that will minimize the consequences of sensory discordance in reduced energy foods. This priming project will have quantified the discordance between sensory signals and nutrient feedback in reduced fat food matrices, and designed snack food models that rebalance these signals leading to satisfying and satiating reduced fat foods. This model approach can then be rolled out to low sugar foods. However it will also enable subsequent projects to address the following research objectives:
Define inter-individual differences in the mouth-gut-brain relationship, and explore whether these are driven by phenotype or genotype.
Define the impact of reduced fat foods on GI hormone release and endocannabinoid response to further understand mechanisms underpinning the interrelationship between mouth, gut and brain. This will lead to predictive models through a systems biology approach.
Develop novel technological approaches to develop foods that can target and balance the delivery of sensory and nutrient signals.
Extend these approaches into developing real foods and determine the effect in whole meal scenarios. Long term dietary intervention and consumer behaviour studies will determine the long term impact on health in different population groups.
In addition to the academic research community, the outputs of this research will benefit a range of stakeholders. The research will address key questions that will help BBSRC deliver on its Food, Nutrition and Health research priority, as described above under academic beneficiaries. The food industry will be a key beneficiary through a fundamental understanding of how reduced energy foods impact on satiety, consumption and energy intake. This will lead to the development of food design strategies that will be more effective in achieving fat and sugar reduction goals. More effective food products will be more popular with consumers and therefore lead to improved satisfaction and repeat purchase. Consumers will ultimately benefit from this research through the development and availability of improved quality and more effective reduced energy foods. This strategy will not only benefit consumers who are actively seeking to control energy intake, but we envisage that these energy reduction strategies will become a standard approach in a wide range of standard, commonly consumed foods, that will an impart appropriate level of expected satiety, and thus should have a more widespread impact on energy intake. Following further work on different population groups, individuals who would benefit from these types of interventions will be more easily identified, and matched with appropriate solutions. The government and health care providers will benefit from this knowledge through the improvement of health and nutrition policies. These policies will not simply recommend reductions in dietary energy intake, but rather a tailored dietary advice that accounts for individual phenotype that will result in a more effective sustainable diet for improved weight control. As most cases of obesity are the result of lifelong moderate overconsumption, this research should ultimately help contribute to a reduction in incidence of obesity, by moderating dietary intake over the lifecourse. This will eventually lead to better control over the incidence of related metabolic diseases such as type 2 diabetes and cardiovascular disease.
The project provides excellent training opportunity for staff and students. It will expose them to a broad yet integrated multidisciplinary approach to solving an important diet and health issue; vital experience for future researchers working in this field.

Publications

10 25 50
 
Description One of our main objectives was to establish that Mouth-Gut Discordance existed. We aimed to use a fat reduced emulsion model and quantify the discrepancy between expected satiety from sensory signals and measured satiety through a preload consumption study. We now have the data to confirm this key finding. We developed a mayonnaise-model served on a crispbread as a preload snack where all volunteers consumed the full 35 g portion size. A 3-way study design was conducted where the products were the positive control (31% fat) and two 60% fat reduced samples both containing 12 % fat, one where the mouthfeel was matched using a water-oil-water (WOW) double emulsion system and one where it was not (negative control). Volunteers rated expected satiety of all 3 products to be the same, despite finding a perceptual difference where they rated the negative control to be significantly less thick and less mouthcoating than both the positive control and the WOW reduced fat sample. However, consumption of the ad-libitum lunch one hour later demonstrated that there was a significant difference in post-ingestive satiety between the samples. The mean intake of the ad-libitum meal following the high fat positive control snack was significantly higher than the consumption following the low fat negative control, proving mouth-gut discordance between expected and post-ingestive satiety. Furthermore, although the sensory mouthfeel perception of the WOW low fat mayonnaise matched the positive control, the mean intake of the ad-libitum meal following consumption of this snack was almost identical to that following the negative control. This implies that matching the sensory mouthfeel characteristics of high fat products when reformulating as low fat products could still lead to a difference in post-ingestive satiety and compensation at the subsequent meal. Interestingly, we also asked our volunteers to rate desire for fatty foods at three time points following consumption of the preload snack and before serving the ad-libitum lunch, this desire was significantly less following the positive control whereas ratings following the mouthfeel matched preload mirrored the negative control. Therefore, this is further evidence to suggest that in reformulating high fat products we should consider factors other than sensory mouthfeel. Our second study within this grant is progressing to understand the impact of changing the oral free fatty acid gustatory signal on post-ingestive satiety, and measuring biomarkers within the preload study design.
The multiple emulsions developed and used in the project have been demonstrated to be a useful research tool in terms of optimising sensory perception of fat content in a range of model foods with a range of fat contents. These systems have been utilised through the human trials to understand the interplay between the sensory perception of fat content, expected satiety and actual changes in appetite following consumption of a test meal.
Together with the findings from the human trials, we are planning to develop further funding applications to determine in more detail the mechanisms underpinning this effect, and ultimately how the sensory properties and energy content of foods can be manipulated in a rational way to help develop foods with more effective appetite control to aid the management of energy intake and weight gain.
Exploitation Route Our current results on expected satiety, which also include understanding of individual differences in sensory perception, are of use to product developers in the food industry.
We intend that the results of this intial pliot study will lead to a fully powered study aiming to design sensory and nutrient signals within a reformulated low fat product that will lead to the same post-injestive satiety as the standard full fat product. Evidence from this study should then be instrumental in designing reduced fat / reduced energy food products.
Sectors Agriculture, Food and Drink

 
Description Outputs planned will describe the relationship between expected satiety, the mismatch between sensory expectation and nutrient delivery and actual satiety. New knowledge is anticipated regarding the relationship between expected satiety, the mismatch between sensory expectation and nutrient delivery and actual satiety. This will lead to the development of more rationally designed lower energy foods. Potentially impact with policy makers, providing evidence that moderate reductions in energy content in foods may be more effective than the wholesale reductions required to achieve labelling claims for reduced fat or sugar.
First Year Of Impact 2018
Sector Agriculture, Food and Drink
Impact Types Societal,Policy & public services

 
Title Battery of sensory tests to characterise differences between consumers in fat perception 
Description Battery of sensory tests to characterise differences between consumers in fat perception which combines mouthfeel perception as well as gustatory fat perception. 
Type Of Material Physiological assessment or outcome measure 
Year Produced 2017 
Provided To Others? No  
Impact Once published we suggest that this method will become the accepted method by which to characterise differences between consumers in fat perception. 
 
Description Industry Partners PepsiCo 
Organisation PepsiCo
Country United States 
Sector Private 
PI Contribution We (University of Reading and Quadram) have worked with Pepsico to enable the spraying of fat reduced emulsions onto expanded snacks - snacks that are needed in the Mouth Gut Brain research project.
Collaborator Contribution PepsiCo have modified and manufactured snacks for use in the Mouth Gut Brain research project and carried out testing of the snacks (micro testing, fat and salt content). They contribute to monthly Skype meetings as well as the quarterly project meetings. They have contributed to the design of the project.
Impact No output to date, however the materials supplied for testing are integral to the project and hence will directly contribute to later outputs..
Start Year 2017
 
Description Industry Partners Unilever 
Organisation Unilever
Department Unilever Research and Development
Country United Kingdom 
Sector Private 
PI Contribution We have demonstrated our consumer sensory characterisation methods to the Unilever collaboorators.
Collaborator Contribution Unilever have input to the design of the research and contributed to monthly skype meetings as well as quarterly project team meetings.
Impact None to date.
Start Year 2017
 
Description Industry Stakeholder Arla 
Organisation Arla Foods
Country United Kingdom 
Sector Private 
PI Contribution The Arla team have visited Reading to go through the consumer sensory characterisation methods. We have shared results and stakeholder meetings.
Collaborator Contribution Arla contribute to quarterly stakeholder meetings. Although a financial figure has not been assigned to this in-kind contribution, it has to date involved two members of Arla staff for 3 full days.
Impact None to date
Start Year 2017
 
Description Industry Stakeholder Mars 
Organisation Mars Wrigley Confectionery UK Ltd
PI Contribution We have shared all results to date at stakeholder meetings.
Collaborator Contribution Mars contribute to quarterly stakeholder meetings and have agreed to host the September 2018 meeting on their Slough site. Although a financial figure has not been assigned to this in-kind contribution, it has to date involved one member of Mars staff for 3 full days.
Impact none to date
Start Year 2017
 
Description Industry Stakeholder Mondelez 
Organisation Mondelez International
Country United States 
Sector Public 
PI Contribution Results shared at stakeholder meetings.
Collaborator Contribution Mondelez contribute to quarterly stakeholder meetings and have hosted one meeting on their Reading site. Although a financial figure has not been assigned to this in-kind contribution, it has to date involved one member of Mondelez staff for 3 full days plus the costs associated with the on site meeting.
Impact note to date
Start Year 2017
 
Description Industry Stakeholder Pladis 
Organisation Pladis
PI Contribution Results have been shared at stakeholder meetings.
Collaborator Contribution Pladis contribute to quarterly stakeholder meetings. Although a financial figure has not been assigned to this in-kind contribution, it has to date involved one member of pladis staff for 2 full days.
Impact note to date
Start Year 2017
 
Description Industry Stakeholder Premier Foods 
Organisation Premier Foods Group Ltd
Country United Kingdom 
Sector Private 
PI Contribution Results shared at stakeholder meetings.
Collaborator Contribution Premier Foods contribute to quarterly stakeholder meetings and have hosted one meeting on their Worksop site. Although a financial figure has not been assigned to this in-kind contribution, it has to date involved two members of Premier staff for 3 full days, plus the costs of hosting one meeting.
Impact note to date
Start Year 2017
 
Description Eurosense 2018 (Eighth European Conference on Sensory and Consumer Research) 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Third sector organisations
Results and Impact Oral Presentation entitled "Exploring the influence of sensorial cues of fat perception on expected satiety and post-ingestive satiety of a model food matrix varying in fat content" given by our postdoctoral researcher, Dr Xirui Zhou.
Year(s) Of Engagement Activity 2018
 
Description Food the vital Ingredient launch 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Professional Practitioners
Results and Impact Presented and discussed the role of the physical chemistry of food as part of the launch of the book "Food the Vital Ingredient" to member of the Royal Society of Chemistry
Year(s) Of Engagement Activity 2019
URL http://www.rsc.org/Membership/Networking/InterestGroups/Food/index.asp?e=1
 
Description IFST Sensory Science Groups workshop on the 14th November 2018 "Celebrating Individuality" 
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 Oral presentation entitled " Individual difference in oral fat perception, its impact on fat consumption and preference and the potential factors resulting in such individual difference"; given by our postdoctoral researcher, Dr Xirui Zhou.
Year(s) Of Engagement Activity 2018
 
Description Project Stakeholder meeting 
Form Of Engagement Activity A formal working group, expert panel or dialogue
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Industry/Business
Results and Impact First stakeholder meeting to discuss the project potential for impact and determine the key priorities
Year(s) Of Engagement Activity 2017
 
Description Project Stakeholder meeting 2 
Form Of Engagement Activity A formal working group, expert panel or dialogue
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Industry/Business
Results and Impact Consultation with stakeholders to review progress, gain expert advice / input to the project and agree next steps
Year(s) Of Engagement Activity 2017
 
Description Project Stakeholder meeting 3 
Form Of Engagement Activity A formal working group, expert panel or dialogue
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Industry/Business
Results and Impact Stakeholder consultation meeting to review progress, gain expert input and contributions and agree next steps
Year(s) Of Engagement Activity 2018
 
Description Public lecture and Discussion Eaton Summer Programme 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Public/other audiences
Results and Impact Public lecture and discussion session as part of the Eaton Summer Programme in Norwich in August 2018. Talk entitled "Are your eyes bigger than your belly? The science behind controlling digestion and reducing appetite"
Aimed to educate the public on the role of food structure on digestion and health outcomes. To inform of the developments with the new Quadram Institute aims and research objectives. Enter into a discussion with the audience regarding the health benefits of certain foods and the role of processing, preparation and structure on nutrient availability.
Year(s) Of Engagement Activity 2018
 
Description Stakeholder Meetings 
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 Stakeholder meetings held quarterly with the industry stakeholders and industry partners: May 4th 2017, November 3rd 2017, February 19th 2018, 1st May 2018 and 6th December 2018. One final meeting will be held on 12th June 2019.
Year(s) Of Engagement Activity 2017,2018
 
Description Talk given 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 Talk given on Mouth Gut Brain project, focusing on fat perception and obesity, at Food Matters Live.
Year(s) Of Engagement Activity 2017