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Dietary Fibres on Gut Fermentation

19 septembre 2026 mis à jour par: Kuan-Yu Lin, University of Bath

Acute Effects of Different Dietary Fibres on Gut Fermentation: A Pilot Study

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.

Aperçu de l'étude

Description détaillée

This study aims to investigate the effect of rapidly fermenting FOS over-and-above slowly fermenting SCF and whether this supports a "spatio-temporal fermentation profile" spanning the entire colonic tract. By balancing fermentation speeds, this strategy holds the potential to maximise total colonic fermentation yield whilst mitigating the adverse symptoms typically associated with isolated high-dose FOS intake. Furthermore, the study explores a split-dosing regimen as an additional temporal strategy; dividing the FOS intake may limit the peak rate of gas production, preventing it from exceeding the gut's natural gas clearance mechanisms, while ensuring a sustained delivery of fermentable substrates.

To evaluate these physiological dynamics, healthy adult participants will complete a randomised, double-blind, crossover trial comprising three distinct acute testing days, separated by 7-day washout periods. Under strict dietary standardisation and overnight fasting conditions, participants will consume meals containing specific dietary fibres. The acute physiological responses will be continuously monitored via non-invasive breath hydrogen and methane analysis to objectively map fermentation kinetics, alongside regular self-reported assessments of gastrointestinal tolerability throughout the testing window.

Type d'étude

Interventionnel

Inscription (Estimé)

20

Phase

  • N'est pas applicable

Contacts et emplacements

Cette section fournit les coordonnées de ceux qui mènent l'étude et des informations sur le lieu où cette étude est menée.

Coordonnées de l'étude

Lieux d'étude

    • Somerset
      • Bath, Somerset, Royaume-Uni, BA2 7AY
        • Recrutement
        • University of Bath
        • Contact:

Critères de participation

Les chercheurs recherchent des personnes qui correspondent à une certaine description, appelée critères d'éligibilité. Certains exemples de ces critères sont l'état de santé général d'une personne ou des traitements antérieurs.

Critère d'éligibilité

Âges éligibles pour étudier

18 ans à 85 ans (Adulte, Adulte plus âgé)

Accepte les volontaires sains

Oui

Sexes éligibles pour l'étude

Tout

La description

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.

Plan d'étude

Cette section fournit des détails sur le plan d'étude, y compris la façon dont l'étude est conçue et ce que l'étude mesure.

Comment l'étude est-elle conçue ?

Détails de conception

  • Objectif principal: Science basique
  • Répartition: Randomisé
  • Modèle interventionnel: Affectation croisée
  • Masquage: Double

Armes et Interventions

Groupe de participants / Bras
Intervention / Traitement
Comparateur actif: SCF Alone

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

Administration of SCF with breakfast.

Expérimental: Single Combined Dose (SCF + FOS)

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.

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

Expérimental: Split-Dosed Combination (SCF + FOS)

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.

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

Que mesure l'étude ?

Principaux critères de jugement

Mesure des résultats
Description de la mesure
Délai
Area Under the Curve (AUC) of Breath Hydrogen and Methane Production
Délai: Baseline (fasting) and every 30 minutes up to 8 hours on each acute test day

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

Mesures de résultats secondaires

Mesure des résultats
Description de la mesure
Délai
Fermentation Kinetic Parameters: Maximum Peak Concentration (Cmax) of Breath Gases
Délai: Baseline (fasting) and every 30 minutes up to 8 hours on each acute test day.

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.

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

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.

Baseline (fasting) and every 30 minutes up to 8 hours on each acute test day.
Acute Gastrointestinal (GI) Tolerability Composite Score
Délai: Baseline (fasting) and every 30 minutes up to 8 hours on each acute test day.

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.

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

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.

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

Collaborateurs et enquêteurs

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Les enquêteurs

  • Chercheur principal: Dylan Thompson, Dr., University of Bath
  • Chercheur principal: Oly Perkin, Dr., University of Bath

Dates d'enregistrement des études

Ces dates suivent la progression des dossiers d'étude et des soumissions de résultats sommaires à ClinicalTrials.gov. Les dossiers d'étude et les résultats rapportés sont examinés par la Bibliothèque nationale de médecine (NLM) pour s'assurer qu'ils répondent à des normes de contrôle de qualité spécifiques avant d'être publiés sur le site Web public.

Dates principales de l'étude

Début de l'étude (Estimé)

26 août 2026

Achèvement primaire (Estimé)

27 août 2027

Achèvement de l'étude (Estimé)

27 août 2027

Dates d'inscription aux études

Première soumission

15 septembre 2026

Première soumission répondant aux critères de contrôle qualité

19 septembre 2026

Première publication (Réel)

23 septembre 2026

Mises à jour des dossiers d'étude

Dernière mise à jour publiée (Réel)

23 septembre 2026

Dernière mise à jour soumise répondant aux critères de contrôle qualité

19 septembre 2026

Dernière vérification

1 septembre 2026

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