The health impact of industrial interesterification of dietary fats

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

Abstract

Dietary fat forms an important part of our diet, however, trans and saturated fats are associated with increased risk of cardiovascular disease. Certain foods, such as spreads and bakery products need solid fat in order to produce desirable taste and texture. However, the health risks associated with trans and saturated fats mean that different approaches to create solid fats are required. One method is to incorporate interesterified fats into foods. Interesterification is an industrial process used for blends of vegetable oils that changes the structure of the fat without changing the overall fatty acid composition in the total fat. This results in a harder fat than the original structure of the vegetable oils, which can be used in place of butter and lard (both high in saturated fat) and partially hydrogenated fats (high in trans fat).

Despite the global use of interesterified fats in a wide range of foods, their health effects have not been investigated. Initial research from our group found that one of the most commonly consumed interesterified fats leads to differences in blood fat levels after consumption compared to the same fat that has not been interesterified. Large rises in blood fats after meals are an important risk factor for cardiovascular disease. This project will investigate the cardiovascular health effects of typically consumed interesterified fats to address this crucial gap in scientific evidence. The project is organised into 3 objectives. Firstly, we will use an existing UK database of dietary intakes in a large, nationally representative study population, together with information on interesterified fat contents of foods provided by a leading food company, to estimate dietary intakes of interesterified fats in the UK. We will use this information to predict what would happen to blood fats if current dietary intakes of interesterified fats were replaced by fats like butter and lard. This will provide the first ever data set on the potential public health impact of including these fats in the UK food supply. We will then undertake a detailed human study to assess the effects of the most commonly consumed interesterified fat, compared to the non-interesterified equivalent fat, and the vegetable oil that the interesterified fat is normally blended with. We will explore the biological reasons why the amount of fat in the blood may differ after consuming these fats. Cutting edge methods will be employed to assess differences in gut handling, fat absorption and the fate of the fats once they are in the blood stream. Finally, we will run a second human study to determine whether blends of different proportions of these fats, i.e. the proportions that are most commonly consumed in products such as "healthier" spreads and bakery fats, have any effects on the factors that influence risk of cardiovascular disease, compared to a control oil that does not contain any interesterified fat, and a second control fat that is entirely interesterified fat. Model digestion methods will be used to understand the mechanisms underpinning the results of the human studies.

The overall aim is to gain a fuller understanding of what contribution these interesterified fats make to the UK diet, why they might lead to differences in blood fat levels and whether this influences known risk factors for cardiovascular disease. Our hypothesis is that the overall effect of consuming these fats, in the quantities available in commercial food products, will reduce cardiovascular disease risk when compared to alternative fats with the same functional properties. The study's findings will provide valuable information to the food industry and will arm nutritionists, dietitians, other health professionals and government policy makers with robust scientific evidence for the potential health impact of consuming interesterified fats which will help, in the longer term, formulate dietary advice for the general public.

Technical Summary

Interesterification (IE) of dietary fats results in the re-esterification of fatty acids across the sn-1, sn-2 and sn-3 positions of the glycerol backbone of triacylglycerol molecules, thereby changing the proportion of saturated fatty acids in the sn-2 position and the solid fat content of the blend. It is now extensively used by the food industry, in place of trans fats, to create fats with desirable functional characteristics. Research into the health effects of IE fats has been sparse and has focused primarily on fats that are rarely used commercially. This project will investigate the potential cardiovascular health effects of commonly consumed IE fats by: 1) combining observational data from the UK National Diet and Nutrition Survey and technical data from the UK's leading IE fat supplier to estimate UK dietary consumption, and to provide model estimates of predicted cardiovascular health effects of their consumption vs. application-appropriate alternatives; 2) investigating the effect of interesterification of a typical blend of palm stearin/palm kernel (PSt/PK) fat, compared to a non-interesterified equivalent, on digestion and postprandial lipid metabolism, using in vivo postprandial studies (single-meal randomised crossover study), stable isotope tracer techniques and in vitro gut modelling; 3) evaluating the acute cardio-metabolic health effects of the different ratios of the most commonly consumed blend ratios compared to reference fats (100% IE PSt/PK and 100% vegetable oil), in a sequential-meal, randomised, crossover, double-blind design. These studies are also designed to unravel the molecular (e.g. sn-2 composition) and physico-chemical (e.g. solid fat content) mechanisms underpinning any differential postprandial lipaemic responses. Outcomes will facilitate an understanding of prevalence of IE fats in the UK diet and potential cardio-metabolic health effects, arming the food industry with knowledge that can be used to maximise health benefits.

Planned Impact

Incorporating interesterified (IE) fats into certain foods yields desirable functional characteristics whilst negating the need for trans fats and reducing the saturated fatty acid (SFA) content by about 10-20%, thereby forming a functional fat with improved predicted health benefits. IE fat blends are estimated to supply between 4-10 % of average daily energy intake (unpublished industry sources), thus there is a pressing need to understand their health effects. Systematically assessing current IE fat intakes in the UK will provide the food industry with valuable data for estimates of typical dietary intakes in the general population and subgroups (sexes, age groups and socio-economic groups etc.). This data, together with model estimates of changes in blood lipids as a result of replacing IE fats with functional alternatives such as traditional fats (butter, lard), or trans fats (now abandoned by the UK food industry due to deleterious health effects), will provide the government with essential public nutrition information on national trends in dietary intakes and potential health implications.

A detailed examination of potential physiological adaptations occurring during digestion, absorption and metabolism of the most commonly consumed IE palm-derived fat blend will bridge the knowledge gap in this neglected area of food and health research. Results will significantly advance the knowledge of food scientists working in the food industry and academia at an international level as to the biological consequences of interesterification. A clearer understanding of the gastrointestinal and metabolic fate of the most commonly consumed IE fat may also inform the design of other IE fats that might be developed in the future for broader food applications.

A full comprehension of the effects of consuming IE fat blends on lipoprotein metabolism, inflammation and endothelial function will help to ensure a safe and sustainable supply of fat with desirable functional characteristics. The outcomes of these studies will contribute a robust body of evidence to support potential claims that could be made by manufacturers regarding the physiological effects of IE fats compared to other application-appropriate fats with the same functionality. This will ultimately contribute to the development of other new products containing variations of IE fat blends which may help to reduce the risk of developing cardiovascular/metabolic disease. In the longer term the study will improve marketing of IE fat-containing products with information about health effects compared to earlier-generation fats (e.g. margarine) with similar functionality, and will lead to a deeper understanding of how delivering different combinations of IE fats with vegetable oils, such as rapeseed and linseed can affect health outcomes.

In addition to the distinct impact on the food industry, and the clear benefit to authorities who advise and formulate nutrition policy, the other direct beneficiary group is the UK population. With an ageing, largely sedentary society and alarming forecasts for trends in type 2 diabetes (T2D), evidence on cardio-metabolic health effects of widely consumed food ingredients such as IE fats will be relevant to most of the population. Treating CVD and T2D currently costs the NHS around £20bn p.a. (approx. 20 % of total budget) and CVD is responsible for over a quarter of all deaths in the UK. The groundswell of popular opinion that traditional fats, such as butter, are healthier than spreads will be tempered by the provision of authoritative consumer information on the influence of IE fat-containing spreads/cooking fats on health outcomes as a specific output of this project. This will empower the general public to make an informed choice when purchasing fats for home-baking, cooking and general consumption. In addition, consumers will benefit from a wider choice of high quality, desirable foods with more clearly defined health benefits.

Publications

10 25 50
 
Description Interesterification of fats changes the melting properties, texture and stability of the fat in foods. Interesterified fats are widely used by the food industry to change the solid fat content of food products at room temperature and body temperature for optimum mouthfeel and functional properties. They have been used to replace trans fats which are no longer used due to their harmful effects on health. If interesterified fats were not used, then food manufacturers would need to use other fat formulations that are higher in saturated fat, which we know increases blood cholesterol concentrations.

The most significant findings were that commonly-consumed interesterified fats, widely used in commercially available spreads, had no adverse effects on the rise in blood fats following a meal. This was true when we compared an interesterified palm-based fat with another fat that was identical in fatty acid composition but had not been interesterified, and it was also the case when we compared a typical commercially available spread containing interesterified fat with functionally-equivalent alternatives (spreadable butter, and another spread that had not been interesterified but differed in the fatty acid composition). This was supported by experiments using an artificial gastric and intestinal digestion model, showing that the digestive handling of the same fat that has either been interesterified or not did not differ. We also found no acute adverse effects on markers of cardiovascular function. Atlhough this project did not address long-term effects, these results suggest that there is no reason to be concerned about using interesterified fats in place of trans fats.

Another significant achievement was that the project estimated intakes of interesterified fats in a representative UK population. This has not been done before as there is no publicly available information on interesterified fat contents of foods (spreads, bakery, biscuits, confectionery, other) and specialist knowledge from a food technologist in the fats and oils industry was needed to estimate content for all the relevant foods in the National Diet and Nutrition Survey Y1-4 database. Once this was done we were able to model the expected increase in saturated fat intake if interesterified fats were no longer used, and also the expected changes to blood cholesterol. Our results showed 1) on average intakes were low (about 1% of total energy intake), but higher in certain subpopulations (older, lower income, white males), 2) certain foods like biscuits could have quite big reductions in saturated fat content by using interesterified fats, 3) on average the effects of replacing interesterified fats with functional equivalents (higher in saturated fatty acids) would have no significant effect on average blood cholesterol levels at the adult population level. In summary, if interesterified fats were no longer used and replaced by functionally equivalent fats with higher saturated fatty acids, it would have minimal effects on intakes of saturated fat and blood cholesterol on average, but certain sectors of the population could be disproportionately adversely affected.
Exploitation Route This project has generated novel and valuable scientific data for a broad range of stakeholders. The findings provide the government (e.g. SACN) with essential public nutrition information on national dietary intakes and potential health implications. The results will advance knowledge of food scientists and academia at an international level and provide the food industry with confidence to reformulate products with interesterified fats to lower saturated fatty acid intake. The evidence showing no differential effect of IE fat on cardiovascular risk factors will provide confidence in a safe supply of industrially processed fat with desirable functional characteristics. This will ultimately contribute to the development of other new products containing variations of IE fat blends which, as a small component of total combined efforts by the food industry to reformulate foods for better health, may help to reduce the risk of developing cardiometabolic diseases. In the longer term the study will lead to a deeper understanding of how delivering different combinations of IE fats with vegetable oils can affect health outcomes. The other direct beneficiary group is the UK population. Consumers will benefit from a wider choice of high quality, desirable foods with more clearly defined health benefits.
Sectors Agriculture, Food and Drink,Healthcare,Manufacturing, including Industrial Biotechology

 
Description This project has resulted in a number of non-academic impacts with industry, non-governmental organisations and the general public. This has been achieved through a number of outputs including: 1. A Matter of Fat: An interactive modular learning tool in collaboration with the British Nutrition Foundation which can be used by the public to learn about fats in general with a section on interesterified fats. There have currently been 18,685 visits to the site since it was launched last year. Many of the users have been schools who have used this as a teaching resource. 2. A Webinar: Fats Forward - exploring the use of fats in our food, today and beyond. This webinar was produced in collaboration with the British Nutrition Foundation and aimed at the general public, industry and health professionals. Since it was aired in Feb 2020 it has had 1002 viewers. The webinar included a section on industrial processes used by the food industry to create functional fats and highlighted our research on interesterified fats. 3. A Pint of Science Event: Processing the Nutribabble - Is natural always best? This Pint of Science event aimed at the general public was a huge success and also resulted in a publicly available video of the event. The event included a discussion of the industrial processes used by the food industry to create functional fats and highlighted our research on interesterified fats. 4. BBC Horizon piece: Sarah Berry was filmed discussing the use of Palm Oil and its versatility in food products due to the different processes that the food industry can use to confer suitable functionality for a variety of applications. 5. The RoundTable on Interesterified Fats in Food (RIFF) was held as a 1 day meeting to inform key stakeholders on 1) the current use of interesterified (IE) fats in the UK food supply; 2) to discuss the latest evidence relating to the health effects of IE fats; 3) to gather valuable insights and research recommendations from a food industry and public health perspective in the context of government advice to reduce saturated fat. Data collected as part of our grant was used as the background for discussions. A Nutrition Bulletin Publication was published in Dec 2019 as a briefing report of the meeting which has been widely disseminated. The participants consisted of: Academia, Food and Drink Federation, British Dietetic Association, Dairy Crest, Tesco, Public Health England, British Nutrition Foundation and Nestle. 6. The findings have also been communicated to a diverse audience through the researchers many communication and dissemination opportunities including: 1) An invited talk at Nestle (Lausanne; 2019) to discuss their position on IE fats: 2) Annual talks at the Cordon Bleu Culinary School on functionality of fats and IE fats: 3) Talk on IE fats to the Institute of Shortening and Edible Oils (ISEO) Technical Committee; 4) Meetings with key stakeholders in the food industry; 5) Talk and discussions at a Campden BRI event for industry members. These various non-academic impacts have resulted in joined up discussions between industry, food service providers, academia and non-governmental organisations with the outcome of a more transparent discussion of the necessity for different industrial processes in the creation of functionally suitable fats and communication of the neutral effect of IE fats on health based on our current evidence. For example, the research has led to discussions with large food companies and in one instance has led to a change in company policy towards using interesterified fats in their biscuits which would lead to a reduction in saturated fat content. This illustrates how the findings may eventually contribute towards reducing UK population saturated fat intakes.
First Year Of Impact 2018
Sector Agriculture, Food and Drink,Education,Healthcare
Impact Types Societal,Policy & public services

 
Description BBSRC Diet and Health Seeding Award
Amount £95,600 (GBP)
Organisation King's College London 
Sector Academic/University
Country United Kingdom
Start 10/2019 
End 02/2020
 
Description Endotoxemia analysis 
Organisation French National Institute of Agricultural Research
Country France 
Sector Academic/University 
PI Contribution Endotoxemia analysis
Collaborator Contribution Endotoxemia analysis of samples from a clinical study
Impact Future work and papers
Start Year 2019
 
Description Lipidomic Analysis 
Organisation King's College London
Country United Kingdom 
Sector Academic/University 
PI Contribution Lipidomic analysis of clilnical trial samples
Collaborator Contribution Analysis of lipidomic samples from a clinical study by Manyl Mayr
Impact Future paper
Start Year 2018
 
Description Microparticle analysis 
Organisation University of Reading
Country United Kingdom 
Sector Academic/University 
PI Contribution Collection of Extracellular vesicles from our postprandial study which Prof. Parveen Yaqoob, at Reading University, will be analysing as part of her DRINC project
Collaborator Contribution Analysis of extracellular vesicles from an acute postprandial lipaemic response.
Impact Future publications from PhD student analysis
Start Year 2018
 
Description Stable Isotope Measurement 
Organisation University of Surrey
Country United Kingdom 
Sector Academic/University 
PI Contribution Dr Barbara Fielding helped analyse the stable isotope samples from the first clinical trial from this grant. In addition, this collaboration lead to a BBSRC equipment award for Dr. Fielding at the University of Surrey.
Collaborator Contribution Analysis of stable isotope samples
Impact Paper in progress
Start Year 2018
 
Description BBC Horizon broadcast on dietary fats 
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 Media (as a channel to the public)
Results and Impact Sarah Berry featured in BBC Horizon discussing the use of palm oil in foods and industrial processes used to make it suitable for a wide variety of applications.
Year(s) Of Engagement Activity 2019
 
Description BNF on-line training course; 'A Matter of Fat' 
Form Of Engagement Activity Engagement focused website, blog or social media channel
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Public/other audiences
Results and Impact The 'Matter of Fat' on-line training course was a mutli-module course consisting of slide presentations, videos and a quiz.
Year(s) Of Engagement Activity 2019
URL https://www.nutrition.training/courses/healthy-eating/a-matter-of-fat/
 
Description Fats Forward - exploring the use of fats in our food, today and beyond 
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 1002 registrants world wide attended the webinar on 23rd Jan 2020.
Year(s) Of Engagement Activity 2020
URL https://www.nutrition.org.uk/component/rseventspro/event/61-free-bnf-webinar-fats-forward-exploring-...
 
Description Processing the Nutribabble - Is Natural Always Best? 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Public/other audiences
Results and Impact Food is important - for life, for health and for enjoyment! In "Processing the Nutribabble" we explored some of the myths around processing and healthy eating through two important nutrients: fat and iron.

70 members of the public joined the KCL research teams for interesterified fats and iron in a fun, pub based seminar with a practical experiment to look at processing foods and how this can benefit health with particular respect to interesterified fats and iron absorption and fortification.
Year(s) Of Engagement Activity 2019
URL https://pintofscience.co.uk/event/processing-the-nutribabble-is-natural-always-best
 
Description RoundTable on Interesterified Fats in Food 
Form Of Engagement Activity A formal working group, expert panel or dialogue
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Industry/Business
Results and Impact The Roundtable on Interesterified Fats in Foods aimed:
- To inform key stakeholders on the current use of interesterified (IE) fats in the UK food supply
- To discuss the latest evidence relating to the health effects of IE fats
- To gather valuable insights and research recommendations from a food industry and public health perspective in the context of government advice to reduce saturated fat

A Nutrition Bulletin Publication was published in Dec 2019 as a briefing report of the meeting.

The participants consisted of:
Academic
Food and Drink Federation
British Dietetic Association
Dairy Crest
Tesco
Public Health England
Nestle
Year(s) Of Engagement Activity 2019
 
Description School visits (London) 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Schools
Results and Impact Both Drs Sarah Berry and Wendy Hall have delivered workshops/ lessons on 'facts about fats' at local primary schools and carried out activities on the fundamental of dietary fat.
Year(s) Of Engagement Activity 2017,2018
 
Description Workshop on Microparticle analysis organised by Reading University 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Other audiences
Results and Impact This workshop was held by the University of Reading (Prof Parveen Yaqoob) to discuss the application of new analysis techniques to measure microparticles. Our research was presented and a new collaboration formed which has resulted int he analysis of samples from the InterMet study.
Year(s) Of Engagement Activity 2018