Dietary Fibres on Gut Fermentation

NCT07837297 | Recruiting

• 1 other identifier: 16901-21733
• Study Type: interventional
• Target: 20
• Locations: 1 country
• Sites: 1

Brief Summary

The goal of this clinical trial is to learn if adding a rapidly fermenting fibre to a meal containing a slow fermenting fibre affects gut bacterial fermentation and digestive comfort in healthy adults aged 18 to 85 years. The main questions it aims to answer are:

• Does the addition of a fast fermenting fibre to a meal containing a slow fermenting fibre change the timing and amount of gas produced by gut bacterial fermentation?
• Does the addition of a fast fermenting fibre as a split dose effectively reduce the digestive discomfort typically caused by consuming a high dose of fibre all at once? Researchers will compare the effect of adding fructo-oligosaccharides (FOS) over-and-above a single dietary fibre (soluble corn fibre). They will also compare whether taking FOS either all at once versus splitting it into two smaller doses affects gut bacterial fermentation and digestive comfort. Participants will:
• Visit the research laboratory for 3 test days, with a 1-week break between visits.
• Avoid certain foods and fast overnight before each test day.
• Eat a test breakfast and lunch containing the dietary fibres in different parts of the meal.
• Provide breath samples every 30 minutes to measure gas produced by gut bacteria.
• Answer survey questions about their digestive comfort every 30 minutes.
• Keep a diary of their bowel movements for 5 days during each test cycle. Short-chain fatty acids (SCFAs) produced through dietary fibre fermentation are essential for maintaining intestinal barrier integrity and regulating systemic metabolism; however, average daily fibre intake frequently remains below recommended levels. While supplementing with highly fermentable fibres, such as fructo-oligosaccharides (FOS), effectively stimulates beneficial microbial activity in the proximal colon, their rapid breakdown often triggers acute gastrointestinal discomfort, including bloating and flatulence. Conversely, soluble corn fibre (SCF) possesses a highly branched structure that ferments slowly and reaches the distal colon, exhibiting excellent gastrointestinal tolerability but yielding a lower initial peak of SCFA production.

Conditions

Healthy Adult

Keywords

Dietary Fibre; Fructo-oligosaccharides; Gastrointestinal Tolerability; Short-Chain Fatty Acids; Soluble Corn Fibre

Outcome Measures

Primary Outcomes (1)

• Area Under the Curve (AUC) of Breath Hydrogen and Methane Production

  Total colonic fermentation yield is evaluated by measuring breath hydrogen and methane concentrations. Breath samples are collected at 30-minute intervals post-intervention using Omed breath analysers. The total production for both gases is quantified independently by calculating their respective AUC values from the averaged concentration-time profiles.

  Baseline (fasting) and every 30 minutes up to 8 hours on each acute test day

Secondary Outcomes (4)

• Fermentation Kinetic Parameters: Maximum Peak Concentration (Cmax) of Breath Gases

  Baseline (fasting) and every 30 minutes up to 8 hours on each acute test day.

• Fermentation Kinetic Parameters: Time to Peak (Tmax) of Breath Gases

  Baseline (fasting) and every 30 minutes up to 8 hours on each acute test day.

• Acute Gastrointestinal (GI) Tolerability Composite Score

  Baseline (fasting) and every 30 minutes up to 8 hours on each acute test day.

• Lower Gastrointestinal Response Assessed by the Bristol Stool Scale (BSS)

  Baseline (fasting) and every 30 minutes up to 8 hours on each acute test day.

Study Arms (3)

SCF Alone

ACTIVE COMPARATOR

Participants will consume a standardised breakfast containing SCF in the drink component. Three hours later, they will consume a standardised low-fibre lunch.

Dietary Supplement: SCF Alone

Single Combined Dose (SCF + FOS)

EXPERIMENTAL

Participants will consume a standardised breakfast containing SCF in the drink component. They will also consume a meal containing a full dose of FOS. Three hours later, they will consume a standardized low-fibre lunch.

Dietary Supplement: SCF and FOS (Single Dose)

Split-Dosed Combination (SCF + FOS)

EXPERIMENTAL

Participants will consume a standardised breakfast containing SCF in the drink component. They will also consume a meal containing half the dose of FOS. Three hours later, they will consume a standardized low-fibre lunch containing the other half of the dose of FOS.

Dietary Supplement: SCF and FOS (Split Dose)

Interventions

SCF and FOS (Split Dose) DIETARY_SUPPLEMENT

Administration of FOS at breakfast and at lunch, over-and-above SCF at breakfast.

Split-Dosed Combination (SCF + FOS)

SCF and FOS (Single Dose) DIETARY_SUPPLEMENT

Administration of FOS as a single dose over-and-above SCF with breakfast.

Single Combined Dose (SCF + FOS)

SCF Alone DIETARY_SUPPLEMENT

Administration of SCF with breakfast.

SCF Alone

Eligibility Criteria

• Age: 18 Years - 85 Years
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• Healthy males and females, aged between 18 and 85 years at the start of the study.
• Self-reported regular bowel habits, defined as an average frequency of between 3 and 21 bowel movements per week (Mitsuhashi et al., 2018). This weekly average accounts for normal daily fluctuations while ensuring an overall healthy baseline.
• Willing and able to comply with all study protocols, including pre-test dietary restrictions (avoiding highly fermentable foods), a 12-hour overnight fast, and consumption of the prescribed dietary fibre test meals.
• Willing to accurately record gastrointestinal symptoms using the Visual Analogue Scale (VAS) and complete the Bristol Stool Scale (BSS) logs over the specified periods.
• Able to understand the study procedures and provide written informed consent.

You may not qualify if:

• History or current diagnosis of chronic gastrointestinal diseases or conditions (e.g., Irritable Bowel Syndrome \[IBS\], Inflammatory Bowel Disease \[IBD\], coeliac disease, chronic constipation, or history of major gastrointestinal surgery).
• Use of systemic antibiotics, prebiotics, probiotics, or medications known to significantly alter gastrointestinal motility within the 3 months prior to the commencement of, or during the study period.
• Known food allergies or severe intolerances to any ingredients present in the test meals (e.g., soluble corn fibre, fructo-oligosaccharides).
• Females who are currently pregnant, planning to become pregnant during the study period, or lactating.
• Currently following a highly restrictive or extreme diet (e.g., strict ketogenic, extreme high-fibre, or medically prescribed diets) that could significantly confound the baseline gut microbiota or fermentation profile.

Sponsors & Collaborators

• University of Bath: lead

Study Sites (1)

University of Bath

Bath, Somerset, BA2 7AY, United Kingdom

RECRUITING

Study Officials

• Dylan Thompson, Dr.

  University of Bath

  PRINCIPAL INVESTIGATOR

• Oly Perkin, Dr.

  University of Bath

  PRINCIPAL INVESTIGATOR

Central Study Contacts

Kuan-Yu Lin

CONTACT

+44 7799056885; kyl205@bath.ac.uk

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: DOUBLE
• Who Masked: PARTICIPANT, INVESTIGATOR
• Purpose: BASIC SCIENCE
• Intervention Model: CROSSOVER
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: PhD researcher

Study Record Dates

• First Submitted: September 15, 2026
• First Posted: September 23, 2026
• Study Start: August 26, 2026
• Primary Completion (Estimated): August 27, 2027
• Study Completion (Estimated): August 27, 2027
• Last Updated: September 23, 2026

Record last verified: 2026-09

Data Sharing

• IPD Sharing: Will not share

Locations

GB (1)