Effects of Changing Intestinal Transit Time on Gut Microbial Composition and Metabolism

NCT ID: NCT06022302

Last Updated: 2025-03-19

Basic Information

• Recruitment Status: COMPLETED
• Clinical Phase: NA
• Total Enrollment: 22 participants
• Study Classification: INTERVENTIONAL
• Study Start Date: 2023-10-03
• Study Completion Date: 2024-11-29

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.

Conditions

Diet, Healthy; Metabolic Disease

Study Design

• Allocation Method: RANDOMIZED
• Intervention Model: CROSSOVER
• Primary Study Purpose: BASIC_SCIENCE
• Blinding Strategy: NONE

Study Groups

High-fiber diet

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.

Group Type: EXPERIMENTAL

Diet + laxative

Intervention Type: 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.

Diet only

Intervention Type: OTHER

This is only a control and participants will not receive Movicol.

Low-fiber diet

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.

Group Type: EXPERIMENTAL

Diet + laxative

Intervention Type: 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.

Diet only

Intervention Type: OTHER

This is only a control and participants will not receive Movicol.

Interventions

Diet + laxative

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.

Intervention Type: DRUG

Diet only

This is only a control and participants will not receive Movicol.

Intervention Type: OTHER

Other Intervention Names

Control

Eligibility Criteria

Inclusion Criteria

• 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.

Exclusion Criteria

• 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

• Minimum Eligible Age: 18 Years
• Maximum Eligible Age: 75 Years
• Eligible Sex: ALL
• Accepts Healthy Volunteers: Yes

Sponsors

Technical University of Denmark

OTHER

Sponsor Role: collaborator

KU Leuven

OTHER

Sponsor Role: collaborator

University of Minnesota

OTHER

Sponsor Role: collaborator

University of Copenhagen

OTHER

Sponsor Role: lead

Responsible Party

Henrik Munch Roager

Associate Professor

Responsibility Role: PRINCIPAL_INVESTIGATOR

Locations

University of Copenhagen, Department of Nutrition, Exercise and Sports

Copenhagen, , Denmark

Countries

Denmark

Other Identifiers

M245

Identifier Type: -

Identifier Source: org_study_id