NCT07594600

Brief Summary

The aim of this crossover intervention study is to evaluate the volatile organic compounds (VOCs) present in participants at baseline and how these levels change after consuming either a low- or high-dietary fiber diet for three days. This study will involve adults, 18-65 years old, without any gastrointestinal diseases. The primary objectives are to characterize baseline VOC profiles, assess changes in these profiles after a short-term dietary fiber intervention, determine if specific VOC patterns correlate with dietary fiber intake, and identify the time points at which VOC levels peak. This information will help establish the optimal timing for breath sampling and potentially help us understand how VOC patterns relate to dietary fiber consumption and degradation. We expect that the high-dietary fiber diet will lead to a more significant increase in VOC levels and potentially a distinct VOC profile compared to the low-dietary fiber diet. Each participant will serve as their own control, allowing for within-subject comparisons of VOC levels at baseline and after both dietary fiber interventions. Participants will receive a whole-food product that is rich in dietary fiber and will consume either a low-fiber diet (10 g/day) or a high-fiber diet (40 g/day) for three days. On the first day of each intervention, participants will also ingest a pH capsule to monitor gastrointestinal pH continuously throughout the three days. After a three-week washout period, participants will cross over to the other intervention arm and undergo another round of gastrointestinal pH monitoring. In addition to the dietary intervention, participants will complete food and health questionnaires to assess their habitual fiber intake and dietary habits. Fecal samples will be collected for in vitro fermentation to functionally profile the gut microbiota by assessing fecal VOCs, short-chain fatty acids (SCFA), and the microbial enzymatic activity and their pH-dependent modulation.

Trial Health

65
Monitor

Trial Health Score

Automated assessment based on enrollment pace, timeline, and geographic reach

Enrollment
20

participants targeted

Target at below P25 for not_applicable

Timeline
9mo left

Started May 2026

Shorter than P25 for not_applicable

Status
not yet recruiting

Health score is calculated from publicly available data and should be used for screening purposes only.

Trial Relationships

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Study Timeline

Key milestones and dates

Study Progress7%
May 2026Mar 2027

Study Start

First participant enrolled

May 1, 2026

Completed
12 days until next milestone

First Submitted

Initial submission to the registry

May 13, 2026

Completed
6 days until next milestone

First Posted

Study publicly available on registry

May 19, 2026

Completed
6 months until next milestone

Primary Completion

Last participant's last visit for primary outcome

November 1, 2026

Expected
4 months until next milestone

Study Completion

Last participant's last visit for all outcomes

March 1, 2027

Last Updated

May 19, 2026

Status Verified

May 1, 2026

Enrollment Period

6 months

First QC Date

May 13, 2026

Last Update Submit

May 13, 2026

Conditions

Healthy Adult ParticipantsAssociation Between Dietary Fiber Intake and Volatile Organic Compound Profiles in Exhaled Breath

Keywords

Volatile Organic CompoundsFood InterventionHealthy participantsNo gastrointestinal diseasesWithout gastrointestinal diseasesDietary Fiber

Outcome Measures

Primary Outcomes (1)

  • Effect of a 3-day low fiber diet compared to a 3-day high fiber diet on the Volatile Organic Compound profiles in exhaled breath

    Volatile Organic Compound profiles in produced by the 3-day low fiber diet intervention compared to the profiles produced by the 3-day high fiber diet, with a 3-week washout inbetween

    5 weeks

Secondary Outcomes (8)

  • Effect of a low fiber diet on Volatile Organic Compound profiles after 4 hours

    4 hours

  • Effect of a low fiber diet on Volatile Organic Compound profiles after 6 hours

    6 hours

  • Effect of a low fiber diet on Volatile Organic Compound profiles after 8 hours

    8 hours

  • Effect of a high fiber diet on Volatile Organic Compound profiles after 4 hours

    4 hours

  • Effect of a high fiber diet on Volatile Organic Compound profiles after 6 hours

    6 hours

  • +3 more secondary outcomes

Other Outcomes (2)

  • Fecal Volatile Organic Compound profiles

    1 week

  • SCFA

    1 Week

Study Arms (2)

Low Fiber Diet, Then High Fiber Diet

EXPERIMENTAL

Participants will receive a whole food dietary fiber product to consume 10g of dietary fiber per day over a total of 3 days, equal to a high fiber diet. After a washout period of 3 weeks, they then receive the same whole food dietary fiber product, to consume 40g of dietary fiber per day in a total of 3 days, equal to a high fiber diet.

Other: Low, High Fiber Diet

High Fiber Diet, Then Low Fiber Diet

EXPERIMENTAL

Participants will receive a whole food dietary fiber product to consume 40g of dietary fiber per day over a total of 3 days, equal to a high fiber diet. After a washout period of 3 weeks, they then receive the same whole food dietary fiber product, to consume 10g of dietary fiber per day in a total of 3 days, equal to a high fiber diet.

Other: High, Low Fiber Diet

Interventions

Low, High Fiber DietOTHER

Dietary Intervention: Low Fiber Diet Whole food dietary fiber product, 10g of dietary fiber consumed per day for 3 days Dietary Intervention: High Fiber Diet Whole food dietary fiber product, 40g of dietary fiber consumed per day for 3 days

Low Fiber Diet, Then High Fiber Diet
High, Low Fiber DietOTHER

Dietary Intervention: High Fiber Diet Whole food dietary fiber product, 40g of dietary fiber consumed per day for 3 days Dietary Intervention: Low Fiber Diet Whole food dietary fiber product, 10g of dietary fiber consumed per day for 3 days

High Fiber Diet, Then Low Fiber Diet

Eligibility Criteria

Age18 Years - 65 Years
Sexall
Healthy VolunteersYes
Age GroupsAdult (18-64), Older Adult (65+)

You may qualify if:

  • Signed informed consent obtained prior to any study-related procedures.
  • Willingness to refrain from regular consumption of prebiotic or probiotic products, as well as medications known to affect gastrointestinal function, for at least four weeks prior to the study visits.

You may not qualify if:

  • History of complicated gastrointestinal surgery.
  • Presence of a gastrointestinal diagnosis or any condition that, in the opinion of the principal investigator, may influence the study outcomes.
  • Current diagnosis of a psychiatric disorder.
  • Systemic use of antibiotics or steroid medications within the past 3 months.
  • Frequent use of NSAIDs (non-steroidal anti-inflammatory drugs) within the 2 months preceding the study visit.
  • Regular consumption of prebiotic or probiotic products within the past 4 weeks.
  • Alcohol or substance abuse.
  • Current smoking or use of nicotine pouches.
  • Frequent use of laxatives, antidiarrheal agents, or anticholinergic medications within the 12 weeks preceding the study visit.
  • Pregnancy or breastfeeding.
  • Respiratory disease or infection.

Contact the study team to confirm eligibility.

Sponsors & Collaborators

Study Officials

  • Robert Brummer, Professor

    Örebro University, Sweden

    STUDY DIRECTOR

Central Study Contacts

Natalie Sundberg PhD Student

CONTACT

+46 704670585natalie.sundberg@oru.se

Robert Brummer, Professor

CONTACT

+46 738426600Robert.Brummer@oru.se

Study Design

Study Type
interventional
Phase
not applicable
Allocation
RANDOMIZED
Masking
DOUBLE
Who Masked
INVESTIGATOR, OUTCOMES ASSESSOR
Purpose
BASIC SCIENCE
Intervention Model
CROSSOVER
Sponsor Type
OTHER
Responsible Party
SPONSOR

Study Record Dates

First Submitted

May 13, 2026

First Posted

May 19, 2026

Study Start

May 1, 2026

Primary Completion (Estimated)

November 1, 2026

Study Completion (Estimated)

March 1, 2027

Last Updated

May 19, 2026

Record last verified: 2026-05