Short Chain Fatty Acids Concentration in Stools, Gut Microbiota Diversity and Composition, Blood Lipid Profiles, Inflammation Biomarkers
Conditions
Keywords
Gut microbiome, Gut microbiota, Dietary fat, Short-chain fatty acids, SCFA, Saturated fat, Monounsaturated fat, Polyunsaturated fat, Butter, Olive oil, Coconut oil, Sunflower oil, MUFA, PUFA
Brief summary
This study will investigate how adding a specific type of dietary fat to daily meals for two weeks affects the gut bacteria and their activity. Participants will be randomly assigned to consume one of four types of fat: butter, coconut oil, olive oil, or sunflower oil (60 mL each day for 2 weeks). Stool and blood samples (after an overnight fast) will be collected at 3 time points during the study (Days 1, 7, and 22). These samples will be used to measure metabolites produced by gut bacteria, the types of bacteria present in the gut, blood lipids, and inflammatory markers. The study, based on previous in vitro findings, aims to understand whether different types of fats (based on their structure and level of saturation) have different effects on gut bacteria and their activity in healthy subjects.
Detailed description
This is a pilot, parallel, randomised controlled dietary intervention trial investigating the effects of dietary fat composition on gut microbiota and metabolic activity in healthy adults. Participants will be randomised to one of four intervention groups (butter, coconut oil, extra virgin olive oil, or sunflower oil), representing commonly consumed dietary fats that differ in fatty acid structure. This study builds on prior in vitro findings demonstrating that fatty acid chain length and degree of saturation influence microbial fermentation pathways and short-chain fatty acid (SCFA) production. The primary objective is to determine whether structurally distinct dietary fats differentially influence gut microbial activity and composition in vivo. Secondary objectives include assessing the effects on cardiometabolic and inflammatory markers. It is hypothesised that dietary fats differing in chain length and degree of saturation will differentially modulate gut microbiota metabolism, with potential systemic effects on circulating cardiometabolic and inflammatory markers. A total of 64 healthy adults aged 20-50 years will be recruited from the Glasgow area. All study visits will take place at the New Lister Building, University of Glasgow. Participants will attend three study visits over a three-week period. The study includes a one-week run-in period (normal habitual diet) followed by a two-week dietary intervention. During the intervention, participants will replace the majority of their habitual dietary fat intake with their allocated fat while maintaining their usual diet and lifestyle. Biological samples (blood and stool) will be collected at each study visit (Day 1, 7 and 22) to assess study outcomes. Anthropometric measurements will also be recorded. Dietary intake, gastrointestinal symptoms, and compliance will be monitored using food diaries, symptom questionnaires, and adherence logs. The sample size is based on anticipated changes in faecal SCFA concentrations. Based on prior data, 14 participants per group provides 80% power (P=0.05) to detect a mean change of 30 μmol/g (SD: 28 μmol/g). Allowing for a 10% drop-out rate, 16 participants per group (64 total) will be recruited. As this is a pilot study, this calculation is intended to inform a reasonable sample size rather than to ensure definitive hypothesis testing.
Interventions
OTHERButter
Participants will consume approximately 65 g/day of butter as their primary dietary fat for 14 days, replacing most habitual dietary fat intake.
OTHERCoconut oil
Participants will consume approximately 55 g/day of coconut oil as their primary dietary fat for 14 days, replacing most habitual dietary fat intake.
Participants will consume 60 mL/day of olive oil as their primary dietary fat for 14 days, replacing most habitual dietary fat intake.
OTHERSunflower Oil
Participants will consume 60 mL/day of sunflower oil as their primary dietary fat for 14 days, replacing most habitual dietary fat intake.
Sponsors
University of Glasgow
Dr Dalia Malkova
Professor Konstantinos Gerasimidis
Study design
Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
BASIC_SCIENCE
Masking
NONE
Eligibility
Sex/Gender
ALL
Age
20 Years to 50 Years
Healthy volunteers
Yes
Inclusion criteria
* Adults aged 20-50 years * Body mass index (BMI) between 20 and 30 kg/m² * Generally healthy * Stable body weight (±2 kg) over the past 2 months * Living in the Glasgow area * Non-smoker
Exclusion criteria
* Use of antibiotics within the past 3 months * Current use of medications affecting gut microbiota or cardiometabolic health * Regular use of dietary supplements that may influence study outcomes (e.g. probiotics, prebiotics, vitamins, minerals, fish oil), unless willing to discontinue prior to study start * Presence of chronic gastrointestinal, metabolic, cardiovascular, hepatobiliary, or pancreatic disease * History of major gastrointestinal surgery * Diagnosed diabetes or use of lipid-lowering therapy * Known fat malabsorption disorders * Pregnant or lactating women * Post-menopausal women * Following a restrictive or specific diet (e.g. vegan, ketogenic diet) * Food allergies or intolerances relevant to study interventions (e.g. dairy, coconut) * Recent significant weight change (±2 kg in the past month) * High reliance on ready meals or takeaway foods (\>7 main meals per week) * Participation in another research study that may interfere with this study
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Change in faecal short-chain fatty acid (SCFA) concentrations | Day 1 (pre run-in), Day 7 (baseline, post run-in), and Day 22 (post-intervention) | Faecal concentrations of short-chain fatty acids (acetate, propionate, and butyrate) will be measured using gas chromatography to assess changes in gut microbial metabolic activity in response to dietary fat intervention. |
| Change in gut microbiota composition | Day 1 (pre run-in), Day 7 (baseline, post run-in), and Day 22 (post-intervention) | Gut microbiota composition will be assessed using 16S rRNA gene amplicon sequencing to evaluate changes in bacterial diversity and relative abundance following the dietary fat intervention. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Change in blood lipid profile | Day 1 (pre run-in), Day 7 (baseline, post run-in), and Day 22 (post-intervention) | Fasting blood concentrations of total cholesterol, LDL-cholesterol, HDL-cholesterol, and triglycerides will be measured using standard enzymatic assays to assess cardiometabolic responses to the dietary fat intervention. |
| Change in inflammatory markers | Day 1 (pre run-in), Day 7 (baseline, post run-in), and Day 22 (post-intervention) | Circulating inflammatory markers (e.g., C-reactive protein (CRP), interleukin-6 (IL-6)) will be measured using ELISA or multiplex assays to assess systemic inflammatory responses to the dietary fat intervention. |
| Change in faecal pH | Day 1 (pre run-in), Day 7 (baseline, post run-in), and Day 22 (post-intervention) | Faecal pH will be measured to assess changes in the gut environment associated with microbial fermentation. |
| Change in fasting glucose concentrations | Day 1 (pre run-in), Day 7 (baseline, post run-in), and Day 22 (post-intervention) | Fasting blood glucose concentrations will be measured to assess changes in glucose metabolism in response to dietary fat intake. |
| Change in faecal fat content | Day 1 (pre run-in), Day 7 (baseline, post run-in), and Day 22 (post-intervention) | Faecal fat content will be measured to assess fat excretion and potential differences in fat digestion and absorption across intervention groups. |
Countries
United Kingdom
Contacts
CONTACTLinah Alhomidan
CONTACTAthanasios Koutsos
PRINCIPAL_INVESTIGATORAthanasios Koutsos
University of Glasgow
PRINCIPAL_INVESTIGATORDalia Malkova, PhD
University of Glasgow
PRINCIPAL_INVESTIGATORKonstantinos Gerasimidis, PhD
University of Glasgow
Outcome results
None listed