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.
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
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
Parallel
Butter
Other interventionParticipants will consume approximately 65 g/day of butter as their primary dietary fat for 14 days, replacing most habitual dietary fat intake.
Coconut oil
Other interventionParticipants will consume approximately 55 g/day of coconut oil as their primary dietary fat for 14 days, replacing most habitual dietary fat intake.
Extra Virgin Olive Oil
Other interventionParticipants will consume 60 mL/day of olive oil as their primary dietary fat for 14 days, replacing most habitual dietary fat intake.
Sunflower Oil
Other interventionParticipants will consume 60 mL/day of sunflower oil as their primary dietary fat for 14 days, replacing most habitual dietary fat intake.
Change in faecal short-chain fatty acid (SCFA) concentrations
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
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.
Change in blood lipid profile
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
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
Faecal pH will be measured to assess changes in the gut environment associated with microbial fermentation.
Change in fasting glucose concentrations
Fasting blood glucose concentrations will be measured to assess changes in glucose metabolism in response to dietary fat intake.
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University of Glasgow
Lead sponsor
Dr Dalia Malkova
Collaborator
Professor Konstantinos Gerasimidis
Collaborator
