Microbial ColonizationGEEFomjebuikNCT05900609
Gut Health Enhancement by Eating Favourable Food
A study testing WholeFiber, Kombucha and Maltodextrin DE19/21 in people with Microbial Colonization, run by VU University of Amsterdam at 1 site in Netherlands.
Trial summary
Within the GEEF om je buik study the effects of an 8-week intervention with either a diet rich in fiber or fermented food on the gut microbiota will be investigated. Read more about this study
- Who is it for?
- Ages 18 to 70 yearsHealthy volunteers can take part
- Conditions the study is for
- Microbial Colonization
- What is being tested?
- WholeFiber, Kombucha and Maltodextrin DE19/21
- Could I receive a placebo?
- Yes, some participants may receive a placebo
- How many people
- 146 participants
- Where
- 1 siteNetherlands
- Study dates
- 22 May 2023to 6 Mar 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 70 years
- All sexes
- Healthy volunteers accepted
- Adult, Older adult
Who may be able to join
- Men and Women, aged ≥18 - ≤70 years;
- Being able to read and speak Dutch;
- Willing to keep a stable dietary pattern throughout the study, apart from the dietary advice in the study;
- Having a smartphone compatible with the Lifedata or PocketQ app to fill out the daily questionnaires.
Who cannot join
- Having a disease or medical condition which can influence the study results such as diabetes, cancer, diagnosed irritable bowel syndrome, renal disease, liver enzyme abnormality, malignant neoplasm, or a history of inflammatory diseases (such as multiple sclerosis, rheumatoid arthritis, and inflammatory bowel disease);
- Having a history of intestinal surgery that might interfere with study outcomes (this does not include an appendectomy or cholecystectomy);
- Average dietary fiber intake of ≥18 gram (women) or ≥22 gram (men) per day, according to the fiber screen questionnaire (see F1 questionnaires);
- More than 3 servings of fermented foods per day as assessed with the fermented food frequency questionnaire (see F1 questionnaires);
- Having a Body Mass Index (BMI) of ≥ 30 kg/m2 (self-reported);
- Currently following a strict diet and unwilling or unable to change; for example, a gluten free diet or a "crash diet" using meal substitutes;
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- Specific food allergies that interfere with dietary intervention (for example, gluten, lactose, etc);
- Use of prebiotics, probiotics and/or synbiotics (this should be stopped 4 weeks before the start of the study) and use of fiber supplements;
- Use of antibiotic treatment less than 3 months before start of the study and/or use of antibiotics during the study;
- Use of medication that can interfere with the study outcomes, as judged by the medical supervisor;
- Alcoholic use of ≥14 (women) or ≥28 (men) glasses of alcoholic beverages per week;
- Use of soft or hard drugs (should be stopped at least 4 weeks before start of the study);
- Being pregnant or lactating;
- Participation in another clinical trial at the same time;
- Student or employee working at either Food, Health and Consumer Research from Wageningen Food and Biobased Research, Microbiology at VU, the MLDS, at WholeFiber, Keep Food Simple or at Cidrani;
- Unable to follow or comply to study rules.
Trial locations and contacts
1 site in 1 country.
Netherlands1 site
Stichting Wageningen Research
Wageningen, Gelderland, 6708 WG
About this study
Within the GEEF om je buik study the effects of an 8-week intervention with either a diet rich in fiber or fermented food on the gut microbiota will be investigated.
Read the detailed description
This study is a randomized controlled trial (RCT) with three intervention groups (high dietary fiber group (HDF), high fermented foods group (HFF), and a control group (CG)). The total duration of the study is 5 months and consists of an 8-week intervention (2-week ramp up period with dietary guidelines, followed by 6-week period with dietary guidelines + additional consumption of study products) and a follow-up after 3 months. In total 147 subjects will be included.
- Conditions
- Microbial Colonization
- Being tested
- WholeFiber, Kombucha, Maltodextrin DE19/21
- Keywords
- Fiber, Fermented food, Immune system, Microbiota
- Medical subject headings
- Communicable Diseases
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
WholeFiberDietary supplement
Also called Chicory roots
WholeFiberTM is a product with high levels of prebiotic dietary fibers (~85%) mainly consisting of inulin, and some pectin, hemi-cellulose and cellulose that is derived from the root vegetable, chicory roots.
Fiber guidelines:
Subjects receive a booklet with recipes high in fiber. Subjects are recommended to use 2 recipes + 2 snacks per day. Estimated average intake via the recipes in the recipe booklet is 24 grams/day.
General guidelines on nutrition and microbiome:
Subjects receive a link to a website with general recommendations to positively alter the gut microbiome (website Voedingscentrum and Dutch Digestive Foundation).
KombuchaDietary supplement
Also called Fermented tea
The kombucha is produced by a minimum three-month long fermentation process. It is a live fermented herbal drink essence, without refined sugar, and an unpasteurized, organic product.
Fermented food guidelines:
Study participants in the fermented foods arm are asked to use 3 additional servings of fermented food per day, using the fermented food list / recipe booklet.
General guidelines on nutrition and microbiome:
Subjects receive a link to a website with general recommendations to positively alter the gut microbiome (website Voedingscentrum and Dutch Digestive Foundation).
Maltodextrin DE19/21Dietary supplement
Maltodextrin DE19/21 is a digestible carbohydrate, that is completely digested and does not reach the colon, which makes it a suitable placebo dietary compound and the reason why it is frequently used in comparable studies.
General guidelines on nutrition and microbiome:
Subjects receive a link to a website with general recommendations to positively alter the gut microbiome (website Voedingscentrum and Dutch Digestive Foundation).
| Study group | Role | What they receive |
|---|---|---|
| Fiber arm | Experimental | Subjects receive dietary guidelines, to increase their fiber intake. Additionally, during the last 6 weeks of the intervention period subjects receive a study product containing 8,5 grams fiber per day.
Additionally, subjects receive general guidelines about the effect of nutrition on the gut microbiome. Receives: Dietary Supplement: WholeFiber |
| Fermented food arm | Experimental | Subjects receive dietary guidelines, to increase their intake of fermented foods.
Additionally, during the last 6 weeks of the intervention period subjects receive a study product of 17 millilitres concentrated kombucha per day.
Additionally, subjects receive general guidelines about the effect of nutrition on the gut microbiome. Receives: Dietary Supplement: Kombucha |
| Control | Placebo comparator | Subjects receive general guidelines about the effect of nutrition on the gut microbiome.
Additionally, during the last 6 weeks of the intervention period subjects receive a placebo product of 10 grams maltodextrin per day. Receives: Dietary Supplement: Maltodextrin DE19/21 |
What is being measured
The primary outcome is the main question the study is designed to answer.
Microbiota diversity
Microbial richness (ASV) using 16s rRNA
Measured: Baseline (week 0)
Microbiota diversity
Microbial richness (ASV) using 16s rRNA
Measured: End ramp-up (week 2)
Microbiota diversity
Microbial richness (ASV) using 16s rRNA
Measured: End intervention (week 8)
Secondary outcomes (61)
Gut microbiota composition
16s rRNA
Measured: Baseline (week 0)
Gut microbiota composition
16s rRNA
Measured: End ramp-up (week 2)
Gut microbiota composition
16s rRNA
Measured: End intervention (week 8)
Carbohydrate Active Enzymes (CAZymes)
Relative abundance of CAZymes using shotgun metagenomic sequencing
Measured: Baseline (week 0)
Carbohydrate Active Enzymes (CAZymes)
Relative abundance of CAZymes using shotgun metagenomic sequencing
Measured: End ramp-up (week 2)
Carbohydrate Active Enzymes (CAZymes)
Relative abundance of CAZymes using shotgun metagenomic sequencing
Measured: End intervention (week 8)
92 inflammatory serum proteins
92 protein biomarkers proteins associated with inflammatory and immune response processes measured in dried blood spots using the Olink target 96 panels. Expressed as normalized protein expression (NPX).
Measured: Baseline (week 0)
92 inflammatory serum proteins
92 protein biomarkers proteins associated with inflammatory and immune response processes measured in dried blood spots using the Olink target 96 panels. Expressed as normalized protein expression (NPX).
Measured: End ramp-up (week 2)
92 inflammatory serum proteins
92 protein biomarkers proteins associated with inflammatory and immune response processes measured in dried blood spots using the Olink target 96 panels. Expressed as normalized protein expression (NPX).
Measured: End intervention (week 8)
Dietary intake
Average intake of fiber, fermented foods and macronutrients using the Traqq app
Measured: Baseline (week 0)
Dietary intake
Average intake of fiber, fermented foods and macronutrients using the Traqq app
Measured: End ramp-up (week 2)
Dietary intake
Average intake of fiber, fermented foods and macronutrients using the Traqq app
Measured: End intervention (week 8)
Dietary intake
Average intake of fiber, fermented foods and macronutrients using the Traqq app
Measured: End follow-up (5 months)
Gastrointestinal complaints
Likert-point scale (scores 0 - 10), for bloating, flatulence and abdominal pain. A higher score means more bloating, flatulence and abdominal pain.
Measured: Daily during intervention (week 0 - week 8)
Stool frequency
Frequency of bowel movement per day
Measured: Daily during intervention (week 0 - week 8)
Stool consistency
Consistency per stool, based on Bristol Stool Score (type 1 -7). Scores 1-7. A higher score means more loose / watery stool.
Measured: Daily during intervention (week 0 - week 8)
Abundance of Prevotella
Based on a faecal smear image, using MicrobeLink tool from HORAIZON (AI, machine learning).
Measured: Baseline (week 0)
Abundance of Prevotella
Based on a faecal smear image, using MicrobeLink tool from HORAIZON (AI, machine learning).
Measured: End ramp-up (week 2)
Abundance of Prevotella
Based on a faecal smear image, using MicrobeLink tool from HORAIZON (AI, machine learning).
Measured: End intervention (week 8)
Abundance of Bacteroides
Based on a faecal smear image, using MicrobeLink tool from HORAIZON (AI, machine learning).
Measured: Baseline (week 0)
Abundance of Bacteroides
Based on a faecal smear image, using MicrobeLink tool from HORAIZON (AI, machine learning).
Measured: End ramp-up (week 2)
Abundance of Bacteroides
Based on a faecal smear image, using MicrobeLink tool from HORAIZON (AI, machine learning).
Measured: End intervention (week 8)
Ratio of Prevotella/Bacteroides
Based on a faecal smear image, using MicrobeLink tool from HORAIZON (AI, machine learning).
Measured: Baseline (week 0)
Ratio of Prevotella/Bacteroides
Based on a faecal smear image, using MicrobeLink tool from HORAIZON (AI, machine learning).
Measured: End ramp-up (week 2)
Ratio of Prevotella/Bacteroides
Based on a faecal smear image, using MicrobeLink tool from HORAIZON (AI, machine learning).
Measured: End intervention (week 8)
Microbial alpha diversity
Based on a faecal smear image, using MicrobeLink tool from HORAIZON (AI, machine learning).
Measured: Baseline (week 0)
Microbial alpha diversity
Based on a faecal smear image, using MicrobeLink tool from HORAIZON (AI, machine learning).
Measured: End ramp-up (week 2)
Microbial alpha diversity
Based on a faecal smear image, using MicrobeLink tool from HORAIZON (AI, machine learning).
Measured: End intervention (week 8)
Transit time
Using blue dye method (two blue muffins)
Measured: Baseline (week 0)
Transit time
Using blue dye method (two blue muffins)
Measured: End ramp-up (week 2)
Transit time
Using blue dye method (two blue muffins)
Measured: End intervention (week 8)
Sleep quality
Athens insomnia scale. Score range: 0-28 points. Higher score means worse outcome.
Measured: Baseline (week 0)
Sleep quality
Athens insomnia scale. Score range: 0-28 points. Higher score indicates worse sleep quality.
Measured: End ramp-up (week 2)
Sleep quality
Athens insomnia scale. Score range: 0-28 points. Higher score indicates worse sleep quality.
Measured: End intervention (week 8)
Sleep quality
Athens insomnia scale. Score range: 0-28 points. Higher score indicates worse sleep quality.
Measured: End follow-up (5 months)
Digestion associated Quality of Life
Digestion associated Quality of Life (DQLQ) questionnaire. Score range: 0-9. Higher score indicates worse digestion associated quality of life.
Measured: Baseline (week 0)
Digestion associated Quality of Life
Digestion associated Quality of Life (DQLQ) questionnaire. Score range: 0-9. Higher score indicates worse digestion associated quality of life.
Measured: End ramp-up (week 2)
Digestion associated Quality of Life
Digestion associated Quality of Life (DQLQ) questionnaire. Score range: 0-9. Higher score indicates worse digestion associated quality of life.
Measured: End intervention (week 8)
Digestion associated Quality of Life
Digestion associated Quality of Life (DQLQ) questionnaire. Score range: 0-9. Higher score indicates worse digestion associated quality of life.
Measured: End follow-up (5 months)
Well-being
World Health Organisation (WHO)-Five Well-Being Index (WHO-5) questionnaire. Raw score ranges from 0-25. Final score is calculated by multiplying the raw score by 4. Final score range 0-100. Higher score indicates better well-being.
Measured: Baseline (week 0)
Well-being
World Health Organisation (WHO)-Five Well-Being Index (WHO-5) questionnaire. Raw score ranges from 0-25. Final score is calculated by multiplying the raw score by 4. Final score range 0-100. Higher score indicates better well-being.
Measured: End ramp-up (week 2)
Well-being
World Health Organisation (WHO)-Five Well-Being Index (WHO-5) questionnaire. Raw score ranges from 0-25. Final score is calculated by multiplying the raw score by 4. Final score range 0-100. Higher score indicates better well-being.
Measured: End intervention (week 8)
Well-being
World Health Organisation (WHO)-Five Well-Being Index (WHO-5) questionnaire. Raw score ranges from 0-25. Final score is calculated by multiplying the raw score by 4. Final score range 0-100. Higher score indicates better well-being.
Measured: End follow-up (5 months)
Subjective health (perception and awareness)
A 2-item questionnaire, which assesses how healthy participants perceive their own health and diet. Score range: 2 - 14, higher scores mean a higher subjective health
Measured: Baseline (week 0)
Subjective health (perception and awareness)
A 2-item questionnaire, which assesses how healthy participants perceive their own health and diet. Score range: 2 - 14, higher scores mean a higher subjective health
Measured: End intervention (week 8)
Subjective health (perception and awareness)
A 2-item questionnaire, which assesses how healthy participants perceive their own health and diet. Score range: 2 - 14, higher scores mean a higher subjective health
Measured: End follow-up (5 months)
Intention to stay healthy (perception + awareness)
A 3-item questionnaire, which assesses the extent to which participants have the intention to eat healthy. Score range: 3 - 21, higher scores mean more intention to stay healthy
Measured: Baseline (week 0)
Intention to stay healthy (perception + awareness)
A 3-item questionnaire, which assesses the extent to which participants have the intention to eat healthy. Score range: 3 - 21, higher scores mean more intention to stay healthy
Measured: End intervention (week 8)
Intention to stay healthy (perception + awareness)
A 3-item questionnaire, which assesses the extent to which participants have the intention to eat healthy. Score range: 3 - 21, higher scores mean more intention to stay healthy
Measured: End follow-up (5 months)
Dietary intrinsic motivation (perception + awareness)
A validated 6-item questionnaire, which assesses whether someone's motivation to eat healthy comes from within a person. Score range: 6 - 42, higher scores mean a higher intrinsic motivation.
Measured: Baseline (week 0)
Dietary intrinsic motivation (perception + awareness)
A validated 6-item questionnaire, which assesses whether someone's motivation to eat healthy comes from within a person. Score range: 6 - 42, higher scores mean a higher intrinsic motivation.
Measured: End intervention (week 8)
Dietary intrinsic motivation (perception + awareness)
A validated 6-item questionnaire, which assesses whether someone's motivation to eat healthy comes from within a person. Score range: 6 - 42, higher scores mean a higher intrinsic motivation.
Measured: End follow-up (5 months)
Dietary self-efficacy (perception + awareness)
A validated 8-item questionnaire, which assesses the extent to which one feels capable of eating healthy. Score range: 8 - 49, higher scores mean a higher self-efficacy
Measured: Baseline (week 0)
Dietary self-efficacy (perception + awareness)
A validated 8-item questionnaire, which assesses the extent to which one feels capable of eating healthy. Score range: 8 - 49, higher scores mean a higher self-efficacy
Measured: End intervention (week 8)
Dietary self-efficacy (perception + awareness)
A validated 8-item questionnaire, which assesses the extent to which one feels capable of eating healthy. Score range: 8 - 49, higher scores mean a higher self-efficacy
Measured: End follow-up (5 months)
Self-regulation (perception + awareness)
A 5-item questionnaire, which assesses the ability to plan and monitor actions. Score range: 5 - 35, higher scores mean a higher self-regulation
Measured: Baseline (week 0)
Self-regulation (perception + awareness)
A 5-item questionnaire, which assesses the ability to plan and monitor actions. Score range: 5 - 35, higher scores mean a higher self-regulation
Measured: End intervention (week 8)
Self-regulation (perception + awareness)
A 5-item questionnaire, which assesses the ability to plan and monitor actions. Score range: 5 - 35, higher scores mean a higher self-regulation
Measured: End follow-up (5 months)
Subjective knowledge (perception + awareness)
A validated 5-item questionnaire, which assesses how knowledgeable someone feels about nutrition and gut microbiota. Score range: 5 - 35, higher scores mean a higher subjective knowledge
Measured: Baseline (week 0)
Subjective knowledge (perception + awareness)
A validated 5-item questionnaire, which assesses how knowledgeable someone feels about nutrition and gut microbiota. Score range: 5 - 35, higher scores mean a higher subjective knowledge
Measured: End intervention (week 8)
Subjective knowledge (perception + awareness)
A validated 5-item questionnaire, which assesses how knowledgeable someone feels about nutrition and gut microbiota. Score range: 5 - 35, higher scores mean a higher subjective knowledge
Measured: End follow-up (5 months)
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted12 Jun 2023
- Study start22 May 2023
- Primary completion26 Nov 2023
- Study completion6 Mar 2024
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Publications (4)Papers the sponsor has linked to this study.
- 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
- Prevention
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Model description
- The study applies a randomized, parallel design of 8 weeks (+ follow-up after 3 months)
- Masking
- None (open label)
- Enrolment
- 146 participants (actual)
Sponsor and investigators
- Lead sponsor
- VU University of Amsterdam
- Sponsor type
- University, hospital or other
- Collaborators
- Wageningen University and Research, Maag Lever Darm Stichting, Cidrani, WholeFiber, Keep Food Simple
- Responsible party
- Principal investigator, Remco Kort, VU University of Amsterdam
- Investigators
- Nicole de Wit, PhD, Principal investigator, Wageningen Food and Biobased ResearchRemco Kort, PhD, Principal investigator, VU University of Amsterdam
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT05900609
- Sponsor's protocol ID
- NL83652.028.23
- Acronym
- GEEFomjebuik
- Status last verified
- Jul 2025
- First submitted
- 3 Apr 2023
- Last updated
- 8 Jul 2025
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No
Publications
Myhrstad MCW, Tunsjo H, Charnock C, Telle-Hansen VH. Dietary Fiber, Gut Microbiota, and Metabolic Regulation-Current Status in Human Randomized Trials. Nutrients. 2020 Mar 23;12(3):859. doi: 10.3390/nu12030859.
PubMed 32210176Stiemsma LT, Nakamura RE, Nguyen JG, Michels KB. Does Consumption of Fermented Foods Modify the Human Gut Microbiota? J Nutr. 2020 Jul 1;150(7):1680-1692. doi: 10.1093/jn/nxaa077.
PubMed 32232406Wastyk HC, Fragiadakis GK, Perelman D, Dahan D, Merrill BD, Yu FB, Topf M, Gonzalez CG, Van Treuren W, Han S, Robinson JL, Elias JE, Sonnenburg ED, Gardner CD, Sonnenburg JL. Gut-microbiota-targeted diets modulate human immune status. Cell. 2021 Aug 5;184(16):4137-4153.e14. doi: 10.1016/j.cell.2021.06.019. Epub 2021 Jul 12.
PubMed 34256014David LA, Maurice CF, Carmody RN, Gootenberg DB, Button JE, Wolfe BE, Ling AV, Devlin AS, Varma Y, Fischbach MA, Biddinger SB, Dutton RJ, Turnbaugh PJ. Diet rapidly and reproducibly alters the human gut microbiome. Nature. 2014 Jan 23;505(7484):559-63. doi: 10.1038/nature12820. Epub 2013 Dec 11.
PubMed 24336217
Study at a glance
From the registry record, last updated by the sponsor on 8 Jul 2025. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Gut Health Enhancement by Eating Favourable Food
- ClinicalTrials.gov ID
- NCT05900609
- Acronym / sponsor ID
- GEEFomjebuik / NL83652.028.23
- Conditions
- Microbial Colonization
- Keywords
- Fiber, Fermented food, Immune system, Microbiota
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 146 participants (actual)
- Lead sponsor
- VU University of AmsterdamUniversity, hospital or other
- Collaborators
- Wageningen University and Research, Maag Lever Darm Stichting, Cidrani, WholeFiber, Keep Food Simple
- Study start
- 22 May 2023 (actual)
- Primary completion
- 26 Nov 2023 (actual)
- Study completion
- 6 Mar 2024 (actual)
- First posted
- 12 Jun 2023 (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.
Within the GEEF om je buik study the effects of an 8-week intervention with either a diet rich in fiber or fermented food on the gut microbiota will be investigated.
Detailed description
This study is a randomized controlled trial (RCT) with three intervention groups (high dietary fiber group (HDF), high fermented foods group (HFF), and a control group (CG)). The total duration of the study is 5 months and consists of an 8-week intervention (2-week ramp up period with dietary guidelines, followed by 6-week period with dietary guidelines + additional consumption of study products) and a follow-up after 3 months. In total 147 subjects will be included.
Study design
- Primary purpose
- Prevention
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- None (open label)
- Number of arms
- 3
- Model description
- The study applies a randomized, parallel design of 8 weeks (+ follow-up after 3 months)
| Arm | Type | Receives |
|---|---|---|
| Fiber arm | Experimental | Dietary Supplement: WholeFiberSubjects receive dietary guidelines, to increase their fiber intake. Additionally, during the last 6 weeks of the intervention period subjects receive a study product containing 8,5 grams fiber per day. Additionally, subjects receive general guidelines about the effect of nutrition on the gut microbiome. |
| Fermented food arm | Experimental | Dietary Supplement: KombuchaSubjects receive dietary guidelines, to increase their intake of fermented foods. Additionally, during the last 6 weeks of the intervention period subjects receive a study product of 17 millilitres concentrated kombucha per day. Additionally, subjects receive general guidelines about the effect of nutrition on the gut microbiome. |
| Control | Placebo comparator | Dietary Supplement: Maltodextrin DE19/21Subjects receive general guidelines about the effect of nutrition on the gut microbiome. Additionally, during the last 6 weeks of the intervention period subjects receive a placebo product of 10 grams maltodextrin per day. |
Who may qualify
- Ages
- 18 to 70 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (4 listed)
- Men and Women, aged ≥18 - ≤70 years;
- Being able to read and speak Dutch;
- Willing to keep a stable dietary pattern throughout the study, apart from the dietary advice in the study;
- Having a smartphone compatible with the Lifedata or PocketQ app to fill out the daily questionnaires.
Key exclusion criteria (16 listed)
- Having a disease or medical condition which can influence the study results such as diabetes, cancer, diagnosed irritable bowel syndrome, renal disease, liver enzyme abnormality, malignant neoplasm, or a history of inflammatory diseases (such as multiple sclerosis, rheumatoid arthritis, and inflammatory bowel disease);
- Having a history of intestinal surgery that might interfere with study outcomes (this does not include an appendectomy or cholecystectomy);
- Average dietary fiber intake of ≥18 gram (women) or ≥22 gram (men) per day, according to the fiber screen questionnaire (see F1 questionnaires);
- More than 3 servings of fermented foods per day as assessed with the fermented food frequency questionnaire (see F1 questionnaires);
- Having a Body Mass Index (BMI) of ≥ 30 kg/m2 (self-reported);
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 |
|---|---|---|
| WholeFiberAlso: Chicory rootsWholeFiberTM is a product with high levels of prebiotic dietary fibers (~85%) mainly consisting of inulin, and some pectin, hemi-cellulose and cellulose that is derived from the root vegetable, chicory roots. Fiber guidelines: Subjects receive a booklet with recipes high in fiber. Subjects are recommended to use 2 recipes + 2 snacks per day. Estimated average intake via the recipes in the recipe booklet is 24 grams/day. General guidelines on nutrition and microbiome: Subjects receive a link to a website with general recommendations to positively alter the gut microbiome (website Voedingscentrum and Dutch Digestive Foundation). | Dietary supplement | Fiber arm |
| KombuchaAlso: Fermented teaThe kombucha is produced by a minimum three-month long fermentation process. It is a live fermented herbal drink essence, without refined sugar, and an unpasteurized, organic product. Fermented food guidelines: Study participants in the fermented foods arm are asked to use 3 additional servings of fermented food per day, using the fermented food list / recipe booklet. General guidelines on nutrition and microbiome: Subjects receive a link to a website with general recommendations to positively alter the gut microbiome (website Voedingscentrum and Dutch Digestive Foundation). | Dietary supplement | Fermented food arm |
| Maltodextrin DE19/21Maltodextrin DE19/21 is a digestible carbohydrate, that is completely digested and does not reach the colon, which makes it a suitable placebo dietary compound and the reason why it is frequently used in comparable studies. General guidelines on nutrition and microbiome: Subjects receive a link to a website with general recommendations to positively alter the gut microbiome (website Voedingscentrum and Dutch Digestive Foundation). | Dietary supplement | Control |
Primary outcome
Microbiota diversity
Time frame: Baseline (week 0)
Microbial richness (ASV) using 16s rRNA
Microbiota diversity
Time frame: End ramp-up (week 2)
Microbial richness (ASV) using 16s rRNA
Microbiota diversity
Time frame: End intervention (week 8)
Microbial richness (ASV) using 16s rRNA
61 secondary outcomes
Gut microbiota composition
Time frame: Baseline (week 0)
Gut microbiota composition
Time frame: End ramp-up (week 2)
Gut microbiota composition
Time frame: End intervention (week 8)
Carbohydrate Active Enzymes (CAZymes)
Time frame: Baseline (week 0)
Carbohydrate Active Enzymes (CAZymes)
Time frame: End ramp-up (week 2)
Carbohydrate Active Enzymes (CAZymes)
Time frame: End intervention (week 8)
92 inflammatory serum proteins
Time frame: Baseline (week 0)
92 inflammatory serum proteins
Time frame: End ramp-up (week 2)
92 inflammatory serum proteins
Time frame: End intervention (week 8)
Dietary intake
Time frame: Baseline (week 0)
Dietary intake
Time frame: End ramp-up (week 2)
Dietary intake
Time frame: End intervention (week 8)
Dietary intake
Time frame: End follow-up (5 months)
Gastrointestinal complaints
Time frame: Daily during intervention (week 0 - week 8)
Stool frequency
Time frame: Daily during intervention (week 0 - week 8)
Stool consistency
Time frame: Daily during intervention (week 0 - week 8)
Abundance of Prevotella
Time frame: Baseline (week 0)
Abundance of Prevotella
Time frame: End ramp-up (week 2)
Abundance of Prevotella
Time frame: End intervention (week 8)
Abundance of Bacteroides
Time frame: Baseline (week 0)
Abundance of Bacteroides
Time frame: End ramp-up (week 2)
Abundance of Bacteroides
Time frame: End intervention (week 8)
Ratio of Prevotella/Bacteroides
Time frame: Baseline (week 0)
Ratio of Prevotella/Bacteroides
Time frame: End ramp-up (week 2)
Ratio of Prevotella/Bacteroides
Time frame: End intervention (week 8)
Microbial alpha diversity
Time frame: Baseline (week 0)
Microbial alpha diversity
Time frame: End ramp-up (week 2)
Microbial alpha diversity
Time frame: End intervention (week 8)
Transit time
Time frame: Baseline (week 0)
Transit time
Time frame: End ramp-up (week 2)
Transit time
Time frame: End intervention (week 8)
Sleep quality
Time frame: Baseline (week 0)
Sleep quality
Time frame: End ramp-up (week 2)
Sleep quality
Time frame: End intervention (week 8)
Sleep quality
Time frame: End follow-up (5 months)
Digestion associated Quality of Life
Time frame: Baseline (week 0)
Digestion associated Quality of Life
Time frame: End ramp-up (week 2)
Digestion associated Quality of Life
Time frame: End intervention (week 8)
Digestion associated Quality of Life
Time frame: End follow-up (5 months)
Well-being
Time frame: Baseline (week 0)
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 8 Jul 2025.
- Background: PubMed 32210176Myhrstad MCW, Tunsjo H, Charnock C, Telle-Hansen VH. Dietary Fiber, Gut Microbiota, and Metabolic Regulation-Current Status in Human Randomized Trials. Nutrients. 2020 Mar 23;12(3):859. doi: 10.3390/nu12030859.
- Background: PubMed 32232406Stiemsma LT, Nakamura RE, Nguyen JG, Michels KB. Does Consumption of Fermented Foods Modify the Human Gut Microbiota? J Nutr. 2020 Jul 1;150(7):1680-1692. doi: 10.1093/jn/nxaa077.
- Results publication: PubMed 34256014Wastyk HC, Fragiadakis GK, Perelman D, Dahan D, Merrill BD, Yu FB, Topf M, Gonzalez CG, Van Treuren W, Han S, Robinson JL, Elias JE, Sonnenburg ED, Gardner CD, Sonnenburg JL. Gut-microbiota-targeted diets modulate human immune status. Cell. 2021 Aug 5;184(16):4137-4153.e14. doi: 10.1016/j.cell.2021.06.019. Epub 2021 Jul 12.
- Results publication: PubMed 24336217David LA, Maurice CF, Carmody RN, Gootenberg DB, Button JE, Wolfe BE, Ling AV, Devlin AS, Varma Y, Fischbach MA, Biddinger SB, Dutton RJ, Turnbaugh PJ. Diet rapidly and reproducibly alters the human gut microbiome. Nature. 2014 Jan 23;505(7484):559-63. doi: 10.1038/nature12820. Epub 2013 Dec 11.
- Individual participant dataSharing planned: No
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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.
Nicole de Wit, PhD principal investigator
Wageningen Food and Biobased Research
Remco Kort, PhD principal investigator
VU University of Amsterdam
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing WholeFiber, Kombucha and Maltodextrin DE19/21 in people with Microbial Colonization, run by VU University of Amsterdam at 1 site in Netherlands.
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 4 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 8 Jul 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 Netherlands. 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. Some participants in this study may receive a placebo. 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?
Microbiota diversity (time frame: Baseline (week 0)). The study lists 3 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
On the ClinicalTrials.gov record for NCT05900609, which also lists 4 linked publications.
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 8 Jul 2025.