Microbial ColonizationFATBOMNCT07019142
High-fat Diet (HFD) and Small Intestinal Microbiome
A study testing HFD in people with Microbial Colonization and Small Intestinal Bacterial Overgrowth, run by Insel Gruppe AG, University Hospital Bern at 1 site in Switzerland.
Trial summary
The investigators aim to characterize the upper small intestinal microbiome in healthy conditions in dependency on feeding condition (starved vs. high-fat-challenged) and diet (before and after 3 day high-fat-diet) Primary outcome will be the maximum culturable bacteria (aerobic and anaerobic) in small intestinal… Read more about this study
- Who is it for?
- Ages 18 to 80 yearsHealthy volunteers can take part
- Conditions the study is for
- Microbial Colonization, Small Intestinal Bacterial Overgrowth
- What is being tested?
- HFD
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 10 participants
- Where
- 1 siteSwitzerland
- Study dates
- 1 Mar 2021to 1 Nov 2024
- Phase
- Interventional
- Are there results?
- None posted in the registry
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 to 80 years
- All sexes
- Healthy volunteers accepted
- Adult, Older adult
Who may be able to join
- Informed Consent as documented by signature (Appendix Informed Consent Form)
- Adults ≥18 years of age
- BMI between 18.5 and 25 kg/m2
Who cannot join
- Contraindications to the class of drugs under study, e.g. known hypersensitivity or allergy to class of drugs or the investigational product,
- Define drugs not allowed during the study or for specific periods of time prior to the administration of the test dose,
- Women who are pregnant or breast feeding,
- Intention to become pregnant during the course of the study,
- Other clinically significant concomitant disease states (e.g., renal failure, hepatic dysfunction, cardiovascular disease, etc.),
- Known or suspected non-compliance, drug or alcohol abuse,
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- Inability to follow the procedures of the study, e.g. due to language problems, psychological disorders, dementia, etc. of the participant,
- Participation in another study with investigational drug within the 30 days preceding and during the present study,
- Previous enrolment into the current study,
- Enrolment of the investigator, his/her family members, employees and other dependent persons,
- inability or unwillingness to provide blood samples and tissue samples (biopsies),
- Participants taking oral anticoagulant or with bleeding disorders who would be at much higher risk of bleeding after biopsy samples or who are contraindicated for an endoscopic examination,
- Uncertain diagnosis, non-resident patients and patients unable to give informed consent
- Patients that undergo chemotherapeutic treatment,
- Patients that have been under antibiotic therapy in the last 4 weeks,
- Pre-existing conditions that would distort results (e.g. SIBO, IBD, obesity, etc.).
Trial locations and contacts
1 site in 1 country.
About this study
Official title: Effects of High-fat Diet (HFD) on Small Intestinal Microbiome in Healthy Volunteers
The investigators aim to characterize the upper small intestinal microbiome in healthy conditions in dependency on feeding condition (starved vs. high-fat-challenged) and diet (before and after 3 day high-fat-diet)
Primary outcome will be the maximum culturable bacteria (aerobic and anaerobic) in small intestinal luminal content during acute liquid-fat challenge before vs. after a short-term (3 day) high-fat-diet
Read more
In this pilot study, healthy volunteers will undergo i) an upper endoscopy for harvesting of small intestinal juice, mucosal biopsies and ii) blood withdrawal at baseline (starved) as well as during acute one-time high-fat luminal stimulation (within 3 hours after baseline) utilizing microbiological culture and 16S-RNA sequencing. The same procedure will be performed after 3 day high-fat-diet.
During endoscopy an acute luminal high-fat challenge which will be repeated after a short-term (3 day) high-fat diet
Read the detailed description
Background: The small intestine represents the major site of lipid metabolism and absorption. Its microbiome has recently been demonstrated to regulate adaptive digestive and absorptive responses to dietary lipids in mice. The microbiome was thereby demonstrated to be a culprit to obesity development. In fact, high-fat diet (HFD) induced changes in the microbiome are most pronounced in the small intestine and transplantation of small bowel microbes from HFD conditions increased lipid absorption compared with low-fat-diet-derived microbes. In humans, HFD induced microbiota alterations has been demonstrated as dysbiosis in colonic and fecal flora9 but changes in the small intestinal microbiome before the onset of obesity have not been addressed so far. In HFD-associated obesity, an increased frequency of small intestinal bacterial overgrowth (SIBO)38 is observed in humans. SIBO so far has been defined as the presence of more than 105 CFU/ml of luminal aspirate or presence of colonic type bacteria determined by microbiological culture techniques5. Therefore, the current definition of SIBO has severe limitations. Specifically, this definition of SIBO is arbitrary, limited to luminal aspirate, aerobic bacteria and assessment in starved conditions. In clinical practice, SIBO is virtually never tested according to this definition. Therefore, it would be of great interest to investigate whether SIBO can be re-defined by investigating the dynamic behavior of the microbiota in the upper small intestine i) before (starved) and after HFD-stimulation and ii) by deep sequencing of 16S-RNA in luminal aspirate as well as biopsies (mucosa-associated compartment). The investigators will perform an observational case-control study in lean healthy volunteers applying an acute (one-time exposure) and short-term (3 day) HFD-challenge assessing duodenal juice and biopsies for quantity and quality of microbial consortia. This will help to define the acute response of the small intestinal microbiome to HFD and ultimately set the stage for a new definition of SIBO.
Moreover, HFD is known to modulate a) the bile-acid-pool and b) gut-derived hormones such as incretins as well as c) thyroid-hormone-status. Thus, impact of acute (one-time exposure) and short-term (3 day) high-fat-stimulation on serum concentration and composition of bile-acids, incretins and thyroid-stimulating-hormone (TSH) plus peripheral thyroid hormones will be assessed.
- Being tested
- HFD
- Medical subject headings
- Communicable Diseases
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
HFDDietary supplement
Luminal challenge with standardized volume, amount, calories of fat
| Study group | Role | What they receive |
|---|---|---|
| HFD-challenge | Other | Luminal application of liquid fat Receives: Dietary Supplement: HFD |
What is being measured
The primary outcome is the main question the study is designed to answer.
Culturable bacteria
Maximum culturable bacteria (aerobic and anaerobic) in small intestinal luminal content during acute liquid-fat challenge before vs. after a short-term (3 day) high-fat-diet
Measured: 3 days
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted13 Jun 2025
- Study start1 Mar 2021
- Primary completion31 May 2024
- Study completion1 Nov 2024
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Microbial ColonizationStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Basic science
- Allocation
- Not applicable
- Intervention model
- Single group
- Model description
- 10 healthy volunteers with descriptive assessment of Primary endpoint
- Masking
- None (open label)
- Enrolment
- 10 participants (actual)
Sponsor and investigators
- Lead sponsor
- Insel Gruppe AG, University Hospital Bern
- Sponsor type
- University, hospital or other
- Responsible party
- Sponsor
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07019142
- Sponsor's protocol ID
- 2020-02116
- Acronym
- FATBOM
- Status last verified
- Jun 2025
- First submitted
- 16 Oct 2020
- Last updated
- 13 Jun 2025
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No: undecided
Study at a glance
From the registry record, last updated by the sponsor on 13 Jun 2025. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Effects of High-fat Diet (HFD) on Small Intestinal Microbiome in Healthy Volunteers
- ClinicalTrials.gov ID
- NCT07019142
- Acronym / sponsor ID
- FATBOM / 2020-02116
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 10 participants (actual)
- Lead sponsor
- Insel Gruppe AG, University Hospital BernUniversity, hospital or other
- Study start
- 1 Mar 2021 (actual)
- Primary completion
- 31 May 2024 (actual)
- Study completion
- 1 Nov 2024 (actual)
- First posted
- 13 Jun 2025 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
The investigators aim to characterize the upper small intestinal microbiome in healthy conditions in dependency on feeding condition (starved vs. high-fat-challenged) and diet (before and after 3 day high-fat-diet)
Primary outcome will be the maximum culturable bacteria (aerobic and anaerobic) in small intestinal luminal content during acute liquid-fat challenge before vs. after a short-term (3 day) high-fat-diet
In this pilot study, healthy volunteers will undergo i) an upper endoscopy for harvesting of small intestinal juice, mucosal biopsies and ii) blood withdrawal at baseline (starved) as well as during acute one-time high-fat luminal stimulation (within 3 hours after baseline) utilizing microbiological culture and 16S-RNA sequencing. The same procedure will be performed after 3 day high-fat-diet.
During endoscopy an acute luminal high-fat challenge which will be repeated after a short-term (3 day) high-fat diet
Detailed description
Background: The small intestine represents the major site of lipid metabolism and absorption. Its microbiome has recently been demonstrated to regulate adaptive digestive and absorptive responses to dietary lipids in mice. The microbiome was thereby demonstrated to be a culprit to obesity development. In fact, high-fat diet (HFD) induced changes in the microbiome are most pronounced in the small intestine and transplantation of small bowel microbes from HFD conditions increased lipid absorption compared with low-fat-diet-derived microbes. In humans, HFD induced microbiota alterations has been demonstrated as dysbiosis in colonic and fecal flora9 but changes in the small intestinal microbiome before the onset of obesity have not been addressed so far. In HFD-associated obesity, an increased frequency of small intestinal bacterial overgrowth (SIBO)38 is observed in humans. SIBO so far has been defined as the presence of more than 105 CFU/ml of luminal aspirate or presence of colonic type bacteria determined by microbiological culture techniques5. Therefore, the current definition of SIBO has severe limitations. Specifically, this definition of SIBO is arbitrary, limited to luminal aspirate, aerobic bacteria and assessment in starved conditions. In clinical practice, SIBO is virtually never tested according to this definition. Therefore, it would be of great interest to investigate whether SIBO can be re-defined by investigating the dynamic behavior of the microbiota in the upper small intestine i) before (starved) and after HFD-stimulation and ii) by deep sequencing of 16S-RNA in luminal aspirate as well as biopsies (mucosa-associated compartment). The investigators will perform an observational case-control study in lean healthy volunteers applying an acute (one-time exposure) and short-term (3 day) HFD-challenge assessing duodenal juice and biopsies for quantity and quality of microbial consortia. This will help to define the acute response of the small intestinal microbiome to HFD and ultimately set the stage for a new definition of SIBO.
Moreover, HFD is known to modulate a) the bile-acid-pool and b) gut-derived hormones such as incretins as well as c) thyroid-hormone-status. Thus, impact of acute (one-time exposure) and short-term (3 day) high-fat-stimulation on serum concentration and composition of bile-acids, incretins and thyroid-stimulating-hormone (TSH) plus peripheral thyroid hormones will be assessed.
Study design
- Primary purpose
- Basic science
- Allocation
- Not applicable
- Intervention model
- Single group
- Masking
- None (open label)
- Number of arms
- 1
- Model description
- 10 healthy volunteers with descriptive assessment of Primary endpoint
| Arm | Type | Receives |
|---|---|---|
| HFD-challenge | Other | Dietary Supplement: HFDLuminal application of liquid fat |
Who may qualify
- Ages
- 18 to 80 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (3 listed)
- Informed Consent as documented by signature (Appendix Informed Consent Form)
- Adults ≥18 years of age
- BMI between 18.5 and 25 kg/m2
Key exclusion criteria (16 listed)
- Contraindications to the class of drugs under study, e.g. known hypersensitivity or allergy to class of drugs or the investigational product,
- Define drugs not allowed during the study or for specific periods of time prior to the administration of the test dose,
- Women who are pregnant or breast feeding,
- Intention to become pregnant during the course of the study,
- Other clinically significant concomitant disease states (e.g., renal failure, hepatic dysfunction, cardiovascular disease, etc.),
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| HFDLuminal challenge with standardized volume, amount, calories of fat | Dietary supplement | HFD-challenge |
Primary outcome
Culturable bacteria
Time frame: 3 days
Maximum culturable bacteria (aerobic and anaerobic) in small intestinal luminal content during acute liquid-fat challenge before vs. after a short-term (3 day) high-fat-diet
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 13 Jun 2025.
- Individual participant dataSharing planned: No. undecided
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
The record lists no contact. Use the official record to reach the sponsor.
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing HFD in people with Microbial Colonization and Small Intestinal Bacterial Overgrowth, run by Insel Gruppe AG, University Hospital Bern at 1 site in Switzerland.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 3 inclusion and 16 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: finished, as of the sponsor's last update on 13 Jun 2025. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in Switzerland. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Culturable bacteria (time frame: 3 days). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 13 Jun 2025.