Effects of Changing Intestinal Transit Time on Gut Microbial Composition and Metabolism
- Conditions
- Diet, HealthyMetabolic Disease
- Interventions
- Drug: Diet + laxativeOther: Diet only
- Registration Number
- NCT06022302
- Lead Sponsor
- University of Copenhagen
- Brief Summary
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.
- Detailed Description
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:
* One week of run-in where participants consume the provided whole-meal diet.
* One week where participants either consume Movicol with the provided whole-meal diet or simply continue consuming the provided whole-meal diet (control).
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.
Recruitment & Eligibility
- Status
- COMPLETED
- Sex
- All
- Target Recruitment
- 22
- 18.5-30.0 kg/m2 BMI
- Self-reported ≤3.5 spontaneous bowel movements per week
- Willing to collect urine and stool samples at home and able to temporarily store them in their own freezer in a provided container.
- Willing to eat the foods provided.
- Owns a smartphone (iOS 11.0 and later or Android 5.0 and up) with access to the internet.
- Pregnant or lactating women.
- Diagnosis of irritable bowel syndrome (IBS), small intestinal bacterial overgrowth (SIBO), inflammatory bowel diseases (IBD), Gastrointestinal obstruction, or Ischemic colitis
- Diagnosed constipation according to the ROME IV criteria
- Intake of antibiotics ˂ 1month, or any medication that can affect the outcomes of the study
- Regular use of diarrhea inhibitors or laxatives
- Dysphagia
- Any chronic disease that can affect the outcomes of the study or pose a risk when consuming Movicol
- Intake of medications potentially altering gastric pH (proton pump inhibitors, histamine receptor antagonists, antacids)
- Intake of medications potentially altering the gastrointestinal motility (prokinetics, antiemetic agents, anti-cholinergic agents, narcotic analgetics, nonsteroidal anti-inflammatory drugs, and peroral glucocorticoids)
- Concurrent participation in another trial
- Any condition that makes the project responsible researcher to doubt the feasibility of the volunteer´s participation
Study & Design
- Study Type
- INTERVENTIONAL
- Study Design
- CROSSOVER
- Arm && Interventions
Group Intervention Description High-fiber diet Diet + laxative 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. High-fiber diet Diet only 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. Low-fiber diet Diet + laxative 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. Low-fiber diet Diet only 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.
- Primary Outcome Measures
Name Time Method Fecal butyrate over urine p-cresol sulfate ratio From visit 1 through to study completion, an average of 7 weeks Changes in ratio between fecal butyrate (reflecting saccharolytic fermentation) and urine p-cresol sulfate (reflecting proteolytic fermentation) between interventions.
- Secondary Outcome Measures
Name Time Method Fecal ammonia concentration From visit 1 through to study completion, an average of 7 weeks Change in ammonia content between interventions.
Concentration of fasting plasma short-chain fatty acids From visit 1 through to study completion, an average of 7 weeks Change in concentration of short-chain fatty acids between interventions.
Fasting plasma concentrations of bile acids From visit 1 through to study completion, an average of 7 weeks Change in concentration of bile acids in fasting blood between interventions.
Fecal metabolome as assessed by untargeted metabolomics From visit 1 through to study completion, an average of 7 weeks Changes in the fecal metabolome between interventions.
Gut microbiome assessed by 16S amplicon sequencing From visit 1 through to study completion, an average of 7 weeks Changes in gut microbiota composition between interventions.
Fasting breath methane and hydrogen levels in parts per million From visit 1 through to study completion, an average of 7 weeks Changes in fasting breath methane and hydrogen concentration measured in parts per million (PPM) in exhalations between interventions.
Change in bowel movement frequency From visit 1 through to study completion, an average of 7 weeks Changes in bowel movement frequency will be measured by the participants recording every bowel movement in a defecation diary during the study.
Whole gut transit time measured by sweet corn From visit 1 through to study completion, an average of 7 weeks Changes in whole gut transit time between interventions determined by the passage time of sweet corn.
Whole gut transit time measured by blue muffins From visit 1 through to study completion, an average of 7 weeks Changes in whole gut transit time between interventions determined by the passage time of muffins with blue dye.
Stool consistency From visit 1 through to study completion, an average of 7 weeks 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.
Fecal water content in percentage of stool weight From visit 1 through to study completion, an average of 7 weeks Change in fecal water content between interventions.
Fecal concentration of short-chain fatty acids From visit 1 through to study completion, an average of 7 weeks Change in concentration of short-chain fatty acids between interventions.
Fecal pH From visit 1 through to study completion, an average of 7 weeks Change in fecal pH level between interventions.
Gut microbiome assessed by shotgun sequencing From visit 1 through to study completion, an average of 7 weeks Changes in gut microbiota composition between interventions.
Microbial metabolites in urine from proteolytic fermentation as assessed by mass spectrometry From visit 1 through to study completion, an average of 7 weeks Changes in the urine concentration of metabolites of microbial proteolysis between interventions.
Microbial metabolites in blood from proteolytic fermentation as assessed by mass spectrometry From visit 1 through to study completion, an average of 7 weeks Changes in the blood concentration of metabolites of microbial proteolysis between interventions.
Trial Locations
- Locations (1)
University of Copenhagen, Department of Nutrition, Exercise and Sports
🇩🇰Copenhagen, Denmark
University of Copenhagen, Department of Nutrition, Exercise and Sports🇩🇰Copenhagen, Denmark