How fast and slow dietary fibres affect gut fermentation and comfort in adults

Is this trial a fit for you?

A plain-English reading of the study's rules. Only the study team can confirm whether you qualify.

What this trial studies

Researchers will use a randomized, double-blind, crossover design in healthy adults to compare three conditions: soluble corn fibre alone, soluble corn fibre with FOS given as a single dose, and soluble corn fibre with FOS given as a split dose. Participants will complete three acute testing days per visit, with a one-week washout between sessions, under standardized meals and overnight fasting. Gas production will be monitored non-invasively via breath hydrogen and methane, while participants report GI symptoms and Bristol Stool Scores to map fermentation timing and tolerability. The goal is to see if balancing fast and slow fermenting fibres can maximize fermentation benefits across the colon while minimizing gas-related discomfort.

Why it matters

Who can join: the full rules

Inclusion Criteria:

* 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.

Exclusion Criteria:

* 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.

Where it's running

• University of Bath
  Bath, Somerset, United Kingdom Recruiting

Study contacts

• Principal investigator: Dylan Thompson, Dr. — University of Bath
• Study coordinator: Kuan-Yu Lin
• Email: kyl205@bath.ac.uk
• Phone: +44 7799056885

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How to take part

1. Review the eligibility criteria above with your treating physician.
2. Check the official listing on ClinicalTrials.gov for the latest contact details and recruitment status.
3. Contact the study coordinator or principal investigator to ask for pre-screening. Pre-screening is free and never obligates you to enroll.