Plain English Summary
Background and study aims
Dietary fibre is anything that we eat that our body is unable to breakdown or digest. However, in our guts we have trillions of bacteria, collectively known as the gut microbiota, that are able to ‘eat’ the fibre in our food. This process allows the gut microbiota to produce energy to survive and grow. The main ‘end-products’ of this process are called short chain fatty acids (SCFA) and scientific work is continuing to link these SCFA with improvements in human health. An increased production of SCFA in the gut has been linked to reductions in body weight and improvements in blood glucose levels. We have developed a novel dietary supplement called a propionate-ester that increases the amounts of a SCFA called propionate produced in the gut. Our previous work has shown the feeding the propionate-ester to overweight and obese humans prevented further gains in body weight and reduced the amount of fat in the liver. The current project has two separate studies. The aim of study one is to investigate the effect of the propionate-ester on blood glucose levels in overweight adults. The aim of study two is to look at the effect of the propionate-ester on the amounts of liver fat in individuals with a previous diagnosis of non-alcoholic fatty liver disease (a condition where individuals have higher levels of liver fat).
Who can participate?
Adults aged 18 to 65 who have a BMI between 25-41 kg/m2.
What does the study involve?
If you participate in Study 1, you will be asked to complete three supplementation periods lasting 42 days. During each supplementation period you will be provided with a different dietary fibre to add to your diet. The dietary fibres are all in a powder form that mixes easily into your normal food and drink. At the end of each 42 day period you will be asked to attend our Clinical Research Facility where we will collect blood samples to look at the effects of each dietary fibre on your blood glucose levels. If you participate in Study 2, you will be asked to complete a single 42 day supplementation period. You will be provided with a dietary fibre to mix into your normal diet. Before and at the end of the 42 day period you will be asked to attend our Clinical Research Facility where we will conduct a liver scan to look at the effects of the dietary fibre on liver fat levels.
What are the possible benefits and risks of participating?
There are no direct benefits or risks of taking part in either study.
Where is the study run from?
Imperial College London (UK)
When is the study starting and how long is it expected to run for?
February 2014 to July 2017
Who is funding the study?
Biotechnology and Biological Sciences Research Council (BBSRC) (UK)
Who is the main contact?
Dr Edward Chambers (Scientific)
Dr Edward Chambers
Du Cane Road
Effect of increased propionate in the colon on appetite and glucose homeostasis
Increased intake of dietary fibre has been associated with reduced appetite and weight loss. In particular, evidence suggests that the fermentable component of dietary fibre is critical in mediating these satiating effects. The short chain fatty acids (SCFAs) produced by microbial fermentation of dietary fibre in the colon have been shown to stimulate the release of appetite suppressing hormones peptide YY (PYY) and glucagon like peptide-1 (GLP-1). Increasing colonic SCFA levels is therefore an attractive target for appetite modulation. To overcome the unpalatably high levels of fermentable dietary fibre needed to significantly increase colonic SCFA levels, we have developed a novel delivery system targeting the release of gram quantities of the SCFA propionate in the human colon. A propionate ester has been produced whereby propionate is chemically bound by an ester bond to inulin, a natural dietary fibre composed mainly of fructose. The majority of propionate bound to inulin should only be released when the inulin polymer is fermented by the colonic microbiota, thus providing targeted colonic delivery. Our previous studies (Effect of Fibre Products on Appetite and Weight; REC Reference: 08/H0707/99) have found that acute ingestion of propionate ester increases plasma PYY and GLP-1 concentrations and reduces food intake. Furthermore, long-term (24 weeks) ingestion of propionate ester significantly reduced body weight gain and the development of abdominal adipose tissue, major risk factors in the development of insulin resistance and diabetes. The current protocol comprises two follow-on studies which have the following aims:
1. Confirm the appetite suppressing effects of propionate ester when incorporated into a food product.
2. Assess the effects of propionate ester on glucose and lipid metabolism.
3. Investigate the impact of propionate ester on hepatic steatosis in adults with non-alcoholic fatty liver disease (NAFLD).
London – Brent, 19/05/2014, ref: 14/LO/0645
Randomised; Interventional; Design type: Not specified
Primary study design
Secondary study design
Randomised controlled trial
Patient information sheet
Not available in web format, please use contact details to request a participant information sheet
Topic: Primary Care, Metabolic and endocrine disorders; Subtopic: Metabolic and Endocrine (all Subtopics), Metabolic and endocrine disorders; Disease: Metabolic & Endocrine (not diabetes), All Diseases
Study 1: Cellulose, Control; Inulin, Control; Inulin-propionate ester, Inulin-propionate ester; Study Entry : Single Randomisation only
Study 2: Inulin, Control; Inulin-propionate ester, Inulin-propionate ester; Study Entry : Single Randomisation only
Primary outcome measures
Study 1: Glucose homeostasis; Timepoint(s): End of each 6 week intervention
Study 2: Intrahepatocellular lipid content
Secondary outcome measures
Study 1: Body composition; Timepoint(s): End of each 6 week intervention
Overall trial start date
Overall trial end date
Participant inclusion criteria
1. Healthy volunteers aged 18-65
2. Male or female
3. Body mass index (weight in kg divided by height in metre squared) of 25-40 kg/m2
1. Male or female aged 18-65 years
2. Body mass index (weight in kg divided by height in metre squared) of BMI of 20-40 kg/m2
3. Histological confirmation of NAFLD in previous 5 years.
4. Controlled blood glucose levels (HbA1c <48 mmol/mol)
Target number of participants
Planned Sample Size: 40; UK Sample Size: 40
Participant exclusion criteria
Study 1 and Study 2:
1. Weight change of more than 3kg in the preceding 3 months
2. Current smokers
3. Substance abuse
4. Excess alcohol intake
7. Cardiovascular disease
9. Gastrointestinal disease e.g. inflammatory bowel disease or irritable bowel syndrome
10. Kidney disease
11. Liver disease
13. Use of medications including: antiinflammatory drugs or steroids, androgens, phenytoin, erythromycin or thyroid hormones
Study 2 has the additional exclusion criteria:
14. Metallic or magnetic implants such as pacemakers
Recruitment start date
Recruitment end date
Countries of recruitment
Trial participating centre
Imperial College London
Biotechnology and Biological Sciences Research Council (BBSRC); Grant Codes: BB/L004259/1
Funding Body Type
Funding Body Subtype
Results and Publications
Publication and dissemination plan
Planned publication in a high-impact peer reviewed journal. Intention to publish in 2018.
IPD sharing statement:
The datasets generated and/or analysed during the current study during this study will be included in the subsequent results publication. The anonymised datasets will be provided as supplementary material in planned publications.
Intention to publish date
Participant level data
Results - basic reporting