Dietary Fibres on Gut Fermentation
ConditionHealthy Adult
Trial statusRecruiting
Trial phaseNot applicable
Trial typeInterventional
Biological sexAll
Age18-85
SponsorUniversity of Bath
About this trial
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.
Eligibility criteria
This trial accepts healthy volunteersQualifiers
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.
Disqualifiers
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.
Trial design
Design model
Crossover
Treatments tested in this trial
SCF Alone
Dietary supplementAdministration of SCF with breakfast.
SCF and FOS (Single Dose)
Dietary supplementAdministration of FOS as a single dose over-and-above SCF with breakfast.
SCF and FOS (Split Dose)
Dietary supplementAdministration of FOS at breakfast and at lunch, over-and-above SCF at breakfast.
Treatment groups
20 Participants
are divided into 3 treatment groupsGroup A: SCF AloneActive comparator 1 intervention
Group B: Single Combined Dose (SCF + FOS)Experimental treatment 1 intervention
Group C: Split-Dosed Combination (SCF + FOS)Experimental treatment 1 intervention
Trial outcomes
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.
Time frame
Baseline (fasting) and every 30 minutes up to 8 hours on each acute test daySecondary outcomes
1
Fermentation Kinetic Parameters: Maximum Peak Concentration (Cmax) of Breath Gases
The dynamic temporal characteristics of gut fermentation are evaluated by determining the maximum peak concentration (Cmax) for both breath hydrogen and methane. Data is extracted from continuous breath samples collected using Omed breath analysers.
Time frame
Baseline (fasting) and every 30 minutes up to 8 hours on each acute test day.2
Fermentation Kinetic Parameters: Time to Peak (Tmax) of Breath Gases
The dynamic temporal characteristics of gut fermentation are evaluated by determining the time required to reach this peak concentration (Tmax) for both breath hydrogen and methane. Data is extracted from continuous breath samples collected using Omed breath analysers.
Time frame
Baseline (fasting) and every 30 minutes up to 8 hours on each acute test day.3
Acute Gastrointestinal (GI) Tolerability Composite Score
The incidence and severity of subjective GI symptoms (bloating, abdominal cramping, stomach noises/borborygmi, and flatulence) are rated by participants on a scale from 0 (absent) to 10 (extremely severe). Any bowel movements are logged and converted into a stool score from 0 (normal transit) to 10 (diarrhoea). These are summed to calculate a total composite score ranging from 0 to 50, with higher scores indicating worse GI tolerability.
Time frame
Baseline (fasting) and every 30 minutes up to 8 hours on each acute test day.4
Lower Gastrointestinal Response Assessed by the Bristol Stool Scale (BSS)
Participants monitor and log their daily bowel movement frequency and utilise the Bristol Stool Scale (BSS) to objectively assess stool consistency and appearance. This tracks delayed lower gastrointestinal responses beyond the immediate acute testing window.
Time frame
Baseline (fasting) and every 30 minutes up to 8 hours on each acute test day.Sponsors and contacts
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Source ClinicalTrials.gov