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Completed

NCT Number: NCT06022302

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

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.

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Key information

Conditions

Diet, Healthy Metabolic Disease Metabolic Diseases Nutritional and Metabolic Diseases

Age range

18 year–75 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

University of Copenhagen, Department of Nutrition, Exercise and Sports

Copenhagen, 1958, Denmark

About this study

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.

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

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

Treatment and study plan

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.

Diet only

Other

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

Other names: Control

Primary outcomes

  1. Fecal butyrate over urine p-cresol sulfate ratio

    Time frame: 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 outcomes

  1. Whole gut transit time measured by sweet corn

    Time frame: 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.

  2. Whole gut transit time measured by blue muffins

    Time frame: 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.

  3. Stool consistency

    Time frame: 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.

  4. Change in bowel movement frequency

    Time frame: 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.

  5. Fecal water content in percentage of stool weight

    Time frame: From visit 1 through to study completion, an average of 7 weeks

    Change in fecal water content between interventions.

  6. Fecal concentration of short-chain fatty acids

    Time frame: From visit 1 through to study completion, an average of 7 weeks

    Change in concentration of short-chain fatty acids between interventions.

  7. Fecal pH

    Time frame: From visit 1 through to study completion, an average of 7 weeks

    Change in fecal pH level between interventions.

  8. Fecal ammonia concentration

    Time frame: From visit 1 through to study completion, an average of 7 weeks

    Change in ammonia content between interventions.

  9. Concentration of fasting plasma short-chain fatty acids

    Time frame: From visit 1 through to study completion, an average of 7 weeks

    Change in concentration of short-chain fatty acids between interventions.

  10. Fasting plasma concentrations of bile acids

    Time frame: From visit 1 through to study completion, an average of 7 weeks

    Change in concentration of bile acids in fasting blood between interventions.

  11. Fasting breath methane and hydrogen levels in parts per million

    Time frame: 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.

  12. Microbial metabolites in urine from proteolytic fermentation as assessed by mass spectrometry

    Time frame: From visit 1 through to study completion, an average of 7 weeks

    Changes in the urine concentration of metabolites of microbial proteolysis between interventions.

  13. Microbial metabolites in blood from proteolytic fermentation as assessed by mass spectrometry

    Time frame: From visit 1 through to study completion, an average of 7 weeks

    Changes in the blood concentration of metabolites of microbial proteolysis between interventions.

  14. Fecal metabolome as assessed by untargeted metabolomics

    Time frame: From visit 1 through to study completion, an average of 7 weeks

    Changes in the fecal metabolome between interventions.

  15. Gut microbiome assessed by shotgun sequencing

    Time frame: From visit 1 through to study completion, an average of 7 weeks

    Changes in gut microbiota composition between interventions.

  16. Gut microbiome assessed by 16S amplicon sequencing

    Time frame: From visit 1 through to study completion, an average of 7 weeks

    Changes in gut microbiota composition between interventions.

Other outcomes

  1. Urine metabolome as assessed by untargeted metabolomics

    Time frame: From visit 1 through to study completion, an average of 7 weeks

    Changes in the urine metabolome between interventions.

  2. Blood metabolome as assessed by untargeted metabolomics

    Time frame: From visit 1 through to study completion, an average of 7 weeks

    Changes in the blood metabolome between interventions.

  3. Fecal microbial metabolites of proteolytic fermentation measured by mass spectrometry

    Time frame: From visit 1 through to study completion, an average of 7 weeks

    Assessment of changes in fecal microbial metabolites of proteolytic fermentation (amino acid-derived metabolites).

  4. Fecal enzymatic activities

    Time frame: From visit 1 through to study completion, an average of 7 weeks

    Assessment of changes in enzymatic activities measured in fecal samples between interventions.

  5. Fecal residual carbohydrate concentration

    Time frame: From visit 1 through to study completion, an average of 7 weeks

    Change in residual carbohydrate concentration measured in fecal samples between interventions.

  6. Fecal energy density

    Time frame: From visit 1 through to study completion, an average of 7 weeks

    Change in fecal energy density measured by bomb calorimetry in fecal samples between interventions.

  7. Fecal redox potential measured in mV

    Time frame: From visit 1 through to study completion, an average of 7 weeks

    Change in redox potential measured in fecal samples between interventions.

  8. Fecal carbon:nitrogen (C:N) ratio

    Time frame: From visit 1 through to study completion, an average of 7 weeks

    Change in C:N ratio measured in fecal samples between interventions.

  9. Fecal microbial load (cells per gram)

    Time frame: From visit 1 through to study completion, an average of 7 weeks

    Change in microbial load in fecal samples between interventions.

  10. Fecal calprotectin concentration

    Time frame: From visit 1 through to study completion, an average of 7 weeks

    Change in concentration of calprotectin measured in fecal samples between interventions. Used as a measure of intestinal inflammation.

  11. Change in various markers related to glucose metabolism

    Time frame: From visit 1 through to study completion, an average of 7 weeks

    Changes in the concentration of various standard markers of glucose metabolism in fasting blood samples between interventions.

  12. Change in various markers related to lipid metabolism

    Time frame: From visit 1 through to study completion, an average of 7 weeks

    Changes in concentration of various standard biochemical markers of lipid metabolism in fasting blood samples between interventions.

  13. Change in various markers of inflammation

    Time frame: From visit 1 through to study completion, an average of 7 weeks

    Change in concentration of various inflammatory markers in fasting blood between interventions.

  14. Change in various appetite hormones

    Time frame: From visit 1 through to study completion, an average of 7 weeks

    Change in concentration of various appetite hormones in fasting blood between interventions.

  15. Urinary creatinine concentration

    Time frame: From visit 1 through to study completion, an average of 7 weeks

    Measurement of urinary levels of creatinine from spot urine samples between interventions.

  16. Amylase gene copy number

    Time frame: At visit 1

    Measurement of amylase gene copy numbers from blood samples at visit 1 to determine the phenotype of the participants.

  17. Change in body weight

    Time frame: From baseline through to study completion, an average of 8 weeks

    Change in body weight is measured using a calibrated digital scale to ensure/monitor weight stability throughout the study.

  18. Measurement of breath hydrogen and methane profiles in parts per million (Area under the curve)

    Time frame: From baseline through to study completion, an average of 8 weeks

    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.

  19. Habitual dietary intake

    Time frame: Before each intervention, 6 days in total

    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.

  20. Change in self-perceived stress level

    Time frame: At visit 1 and after each intervention

    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.

  21. Change in subjective gastrointestinal symptoms

    Time frame: From visit 1 through to study completion, an average of 7 weeks

    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.

  22. Physical activity level

    Time frame: At baseline

    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.

  23. Change in sleep quality

    Time frame: At visit 1 and after each intervention

    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.

Sponsors and collaborators

Lead sponsor

University of Copenhagen

Other

Collaborators

  • KU Leuven
  • Technical University of Denmark
  • University of Minnesota

Registry information

Official study title

Effects of Changing Intestinal Transit Time on Gut Microbial Composition and Metabolism During a Dietary Intervention with Low and High Fiber.

Acronym: PRIMA-KOST

Important dates

Study start
2023
Primary completion
2024
Study completion
2024
First posted
Sep 1, 2023
Registry last updated
Mar 19, 2025

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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