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| Name | Class |
|---|---|
| Technical University of Denmark | OTHER |
| KU Leuven | OTHER |
| University of Minnesota | OTHER |
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The aim of this study is to investigate how a short versus a long transit time impacts the gut microbiome's response to a high-fiber and a low-fiber diet, respectively. Such insights could help us understand personal responses to diets and be a first step towards personalized dietary recommendations targeting the gut microbiome.
The study consists of two parallel arms of whole-meal diets, a low-fiber diet, and a high-fiber diet, respectively. Each arm is designed as a cross-over where participants, in random order, are administered a laxative (Movicol) along with the provided diet to shorten their intestinal transit time or simply consume the provided whole-meal diet (control).
The two intervention periods both involve the following:
Both arms begin with a screening visit and one week where participants consume and record their habitual diets. Subsequently, the first intervention period follows with one visit before and after each of the two weeks (visit 1-3) followed by the second intervention period with one visit before and after each of the two weeks (visit 4-6). The two cross-over periods are split by a washout of at least two weeks.
The study thus runs for approximately 7-8 weeks depending on the length of the washout and consists of seven visits (one screening visit and six regular visits) in total.
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| Label | Type | Description | Intervention Names |
|---|---|---|---|
| High-fiber diet | Experimental | The high-fiber diet will consist of foods rich in dietary fiber such as coarse vegetables, wholegrain bread, and fruits representing a broad range of dietary fibers aiming for ≈40 g of fiber/10 MJ. |
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| Low-fiber diet | Experimental | The low-fiber diet will consist of foods poor in fiber such as white bread and refined foods aiming for ≈10 g of fiber/10 MJ. |
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| Name | Type | Description | Arm Group Labels | Other Names |
|---|---|---|---|---|
| Diet + laxative | Drug | The participants will start by consuming one sacket of Movicol powder (13 g macrogol 3350) on the first day. On day 2, the participants will consume two sackets of Movicol powder (26 g macrogol 3350), one with breakfast in the morning and one before sleep in the evening. The participants will continue consuming two sackets per day (one morning, one evening) until the following study visit, day 8 (seven days in total). If the participants have a very loose stomach (recorded as Bristol stool scale ≥6), they will be instructed to reduce Movicol by one sacket/day. In case the participants have not passed a stool on day 2 or in the morning of day 3, the participants will increase the dose to a maximum of three sackets of Movicol powder (39 g macrogol 3350) per day (morning, noon, and evening) and continue this until the following study visit at day 8. If three sackets cause very loose stomach the participants will decrease the number of sackets consumed. |
| Measure | Description | Time Frame |
|---|---|---|
| Fecal butyrate over urine p-cresol sulfate ratio | Changes in ratio between fecal butyrate (reflecting saccharolytic fermentation) and urine p-cresol sulfate (reflecting proteolytic fermentation) between interventions. | From visit 1 through to study completion, an average of 7 weeks |
| Measure | Description | Time Frame |
|---|---|---|
| Whole gut transit time measured by sweet corn | Changes in whole gut transit time between interventions determined by the passage time of sweet corn. | From visit 1 through to study completion, an average of 7 weeks |
| Whole gut transit time measured by blue muffins |
| Measure | Description | Time Frame |
|---|---|---|
| Urine metabolome as assessed by untargeted metabolomics | Changes in the urine metabolome between interventions. | From visit 1 through to study completion, an average of 7 weeks |
| Blood metabolome as assessed by untargeted metabolomics |
Inclusion Criteria:
Exclusion Criteria:
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| Facility | Status | City | State | ZIP | Country | Contacts |
|---|---|---|---|---|---|---|
| University of Copenhagen, Department of Nutrition, Exercise and Sports | Copenhagen | 1958 | Denmark |
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| ID | Term |
|---|---|
| D008659 | Metabolic Diseases |
| ID | Term |
|---|---|
| D009750 | Nutritional and Metabolic Diseases |
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| ID | Term |
|---|---|
| D004032 | Diet |
| D054368 | Laxatives |
| ID | Term |
|---|---|
| D009747 | Nutritional Physiological Phenomena |
| D000066888 | Diet, Food, and Nutrition |
| D010829 | Physiological Phenomena |
| D005765 | Gastrointestinal Agents |
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Overall, there are two parallel arms (low- and high-fiber diet) to which the participants will be randomized with an allocation ratio 1:1. In each arm participants will be exposed to a crossover design where participants in random order will continue on the meal intervention alone (control) or receive Movicol (a laxative) along with the meal intervention to shorten intestinal transit time.
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| Diet only | Other | This is only a control and participants will not receive Movicol. |
|
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Changes in whole gut transit time between interventions determined by the passage time of muffins with blue dye. |
| From visit 1 through to study completion, an average of 7 weeks |
| Stool consistency | Changes in stool consistency determined by Bristol Stool Scale. The Bristol Stool Scale measures stool consistency on a scale from 1-7 with high numbers reflecting loose stool. | From visit 1 through to study completion, an average of 7 weeks |
| Change in bowel movement frequency | Changes in bowel movement frequency will be measured by the participants recording every bowel movement in a defecation diary during the study. | From visit 1 through to study completion, an average of 7 weeks |
| Fecal water content in percentage of stool weight | Change in fecal water content between interventions. | From visit 1 through to study completion, an average of 7 weeks |
| Fecal concentration of short-chain fatty acids | Change in concentration of short-chain fatty acids between interventions. | From visit 1 through to study completion, an average of 7 weeks |
| Fecal pH | Change in fecal pH level between interventions. | From visit 1 through to study completion, an average of 7 weeks |
| Fecal ammonia concentration | Change in ammonia content between interventions. | From visit 1 through to study completion, an average of 7 weeks |
| Concentration of fasting plasma short-chain fatty acids | Change in concentration of short-chain fatty acids between interventions. | From visit 1 through to study completion, an average of 7 weeks |
| Fasting plasma concentrations of bile acids | Change in concentration of bile acids in fasting blood between interventions. | From visit 1 through to study completion, an average of 7 weeks |
| Fasting breath methane and hydrogen levels in parts per million | Changes in fasting breath methane and hydrogen concentration measured in parts per million (PPM) in exhalations between interventions. | From visit 1 through to study completion, an average of 7 weeks |
| Microbial metabolites in urine from proteolytic fermentation as assessed by mass spectrometry | Changes in the urine concentration of metabolites of microbial proteolysis between interventions. | From visit 1 through to study completion, an average of 7 weeks |
| Microbial metabolites in blood from proteolytic fermentation as assessed by mass spectrometry | Changes in the blood concentration of metabolites of microbial proteolysis between interventions. | From visit 1 through to study completion, an average of 7 weeks |
| Fecal metabolome as assessed by untargeted metabolomics | Changes in the fecal metabolome between interventions. | From visit 1 through to study completion, an average of 7 weeks |
| Gut microbiome assessed by shotgun sequencing | Changes in gut microbiota composition between interventions. | From visit 1 through to study completion, an average of 7 weeks |
| Gut microbiome assessed by 16S amplicon sequencing | Changes in gut microbiota composition between interventions. | From visit 1 through to study completion, an average of 7 weeks |
Changes in the blood metabolome between interventions.
| From visit 1 through to study completion, an average of 7 weeks |
| Fecal microbial metabolites of proteolytic fermentation measured by mass spectrometry | Assessment of changes in fecal microbial metabolites of proteolytic fermentation (amino acid-derived metabolites). | From visit 1 through to study completion, an average of 7 weeks |
| Fecal enzymatic activities | Assessment of changes in enzymatic activities measured in fecal samples between interventions. | From visit 1 through to study completion, an average of 7 weeks |
| Fecal residual carbohydrate concentration | Change in residual carbohydrate concentration measured in fecal samples between interventions. | From visit 1 through to study completion, an average of 7 weeks |
| Fecal energy density | Change in fecal energy density measured by bomb calorimetry in fecal samples between interventions. | From visit 1 through to study completion, an average of 7 weeks |
| Fecal redox potential measured in mV | Change in redox potential measured in fecal samples between interventions. | From visit 1 through to study completion, an average of 7 weeks |
| Fecal carbon:nitrogen (C:N) ratio | Change in C:N ratio measured in fecal samples between interventions. | From visit 1 through to study completion, an average of 7 weeks |
| Fecal microbial load (cells per gram) | Change in microbial load in fecal samples between interventions. | From visit 1 through to study completion, an average of 7 weeks |
| Fecal calprotectin concentration | Change in concentration of calprotectin measured in fecal samples between interventions. Used as a measure of intestinal inflammation. | From visit 1 through to study completion, an average of 7 weeks |
| Change in various markers related to glucose metabolism | Changes in the concentration of various standard markers of glucose metabolism in fasting blood samples between interventions. | From visit 1 through to study completion, an average of 7 weeks |
| Change in various markers related to lipid metabolism | Changes in concentration of various standard biochemical markers of lipid metabolism in fasting blood samples between interventions. | From visit 1 through to study completion, an average of 7 weeks |
| Change in various markers of inflammation | Change in concentration of various inflammatory markers in fasting blood between interventions. | From visit 1 through to study completion, an average of 7 weeks |
| Change in various appetite hormones | Change in concentration of various appetite hormones in fasting blood between interventions. | From visit 1 through to study completion, an average of 7 weeks |
| Urinary creatinine concentration | Measurement of urinary levels of creatinine from spot urine samples between interventions. | From visit 1 through to study completion, an average of 7 weeks |
| Amylase gene copy number | Measurement of amylase gene copy numbers from blood samples at visit 1 to determine the phenotype of the participants. | At visit 1 |
| Change in body weight | Change in body weight is measured using a calibrated digital scale to ensure/monitor weight stability throughout the study. | From baseline through to study completion, an average of 8 weeks |
| Measurement of breath hydrogen and methane profiles in parts per million (Area under the curve) | Measurement of the hydrogen and methane concentrations, in parts per million (PPM), in morning, noon, and evening breath exhalations every day during the study using a portable breath analyzer. | From baseline through to study completion, an average of 8 weeks |
| Habitual dietary intake | Habitual dietary intake will be measured two times over 3 days each using an online 24h dietary record MyFood24 prior to visit 1 and 4. | Before each intervention, 6 days in total |
| Change in self-perceived stress level | Participants' stress levels will be assessed using Cohen's 10-item Perceived Stress Scale (PSS) at visits 1, 3, and 6. Each item is scored on a scale from 1-5 where higher values represent a higher level of self-perceived stress. | At visit 1 and after each intervention |
| Change in subjective gastrointestinal symptoms | Changes in subjective gastrointestinal symptoms reported by participants on a visual analog scale from 0 to 10, where 0 means no symptoms and 10 means the worst possible symptoms. The questionnaire includes the following symptoms: overall stomach and intestinal symptoms, stomachache, flatulence, bloating, constipation, and diarrhea. | From visit 1 through to study completion, an average of 7 weeks |
| Physical activity level | Physical activity will be measured by the International Physical Activity Questionnaire short form (IPAQ-s) at the screening visit. The IPAQ-s consists of 7 items asking about the amount of physical activity (in minutes) at different intensities. The score is the sum of minutes of activity at each intensity level given as metabolic equivalents (METs). The higher the MET score, the more physically active the participant is. | At baseline |
| Change in sleep quality | Changes in sleep pattern and quality will be measured by the Pittsburg Sleep Quality Index (PSQI) at visits 1, 3, and 6. The PSQI consists of 19 items, summed into seven component scores and one overall composite score. Each item is rated on a scale from 0-3 with lower scores reflecting healthier sleep quality. | At visit 1 and after each intervention |
| D045506 | Therapeutic Uses |
| D020228 | Pharmacologic Actions |
| D020164 | Chemical Actions and Uses |