Tolerance to an Artisanal Bread in a Population Intolerant of the Conventional Bread and Study of Associated Markers (TOLERBREAD)

May 4, 2026 updated by: Institut National de Recherche pour l'Agriculture, l'Alimentation et l'Environnement

The objective of this study is to evaluate the effect of consuming an "artisanal" bread for 15 days on gastrointestinal symptoms in individuals intolerant to "conventional" bread.

"Conventional bread" refers to bread made with refined wheat flour (ash = 0.55% of dry matter), containing gluten, and leavened with baker's yeast (Saccharomyces cerevisiae). "Artisanal bread" refers to bread made with whole wheat flour (ash = 1.50% of dry matter) from an ancient durum wheat variety (Russello) and leavened with sourdough.

Study Overview

Status

Recruiting

Conditions

Intervention / Treatment

Detailed Description

Abbreviations:

  • GSRS-IBS: Gastrointestinal Symptom Rating Scale for Irritable Bowel Syndrome
  • GIQLI: Gastrointestinal Quality of Life Index
  • HADS: Hospital Anxiety and Depression Scale
  • FSS: Fatigue Severity Scale
  • LBP: Lipopolysaccharide-Binding Protein

Inclusion Visit (visit 0 [V0])

At the inclusion visit (V0) at Avicenne Hospital (Bobigny), participants will receive study instructions and materials. They will have up to 15 days to:

  • Complete questionnaires (modified GSRS-IBS, Bristol Stool Scale, GIQLI, HADS, FSS)
  • Collect a baseline stool sample, stored at -18°C at home until their first hospital visit (V1).

Wash-out phase (Day-15 [D-15] to Day 0 [D0]):

Participants will follow a gluten-free and low-fructan diet for 15 days. During this period:

  • Daily food intake will be recorded in a diary, with meal photos sent to the research team via a dedicated email
  • On D-8, participants will complete the modified GSRS-IBS and Bristol Stool Scale.
  • On D-1, participants will perform a 24-hour urine collection after ingestion of lactulose (10g) and mannitol (10g) in 200 mL water, divided into three containers:
  • First morning urine
  • 0-5 h collection after sugar ingestion (fasting except water)
  • 5-24 h collection Stool will also be collected on D-1 and stored at 4°C until V1.

First investigation day (Day 0 [D0] - V1):

At 9 a.m., participants arrive the Clinical Research Center (at Avicenne Hospital) with their stool and urine samples.

After completing the questionnaires (modified GSRS-IBS, GIQLI, HADS, FSS, and Bristol Stool Scale), a venous catheter will be inserted for blood sampling.

A 10 mL blood sample will be collected before the test meal. Participants will then consume the test meal (105 g of "artisanal" bread with water).

Postprandial blood samples (2 mL each) will be collected every 30 minutes for 3 hours (total blood volume: 22 mL) The modified GSRS-IBS questionnaire will be completed every hour during the postprandial period If a bowel movement occurs during the visit, the stool sample collected at that time may be used to replace the one collected the previous day.

Intervention phase (D1 to D14):

Participants will continue the same gluten-free, low-fructan diet, with the addition of the "artisanal" bread, which will serve as the sole source of gluten source and the main source of fructans.

  • D1: 75 g of bread
  • D2: 100 g of bread
  • D3-14: 125 g of bread daily (≈ 8.5 g gluten, <1.2 g fructans) Bread consumption may be distributed throughout the day. On D8, participants will again complete the modified GSRS-IBS and Bristol Stool Scale.

Second investigation day (D15 - V2):

On D14, participants will repeat the 24-hour urine and stool collection as previously described. On D15, they will return to the research center and undergo the same procedures as V1.

Measurements:

  • Questionnaires: modified GSRS-IBS (gastrointestinal symptoms), GIQLI, HADS, FSS.
  • Blood: LBP (marker of inflammation), zonulin (marker of intestinal permeability), glucose, insulin.
  • Urine: lactulose and mannitol, with calculation of the lactulose/mannitol ratio as a marker of intestinal permeability.
  • Stool: microbial community analysis (microbiota) and fecal calprotectin (marker of inflammation). Baseline stool samples (before wash-out phase) will also be used to inoculate an artificial colon model for later investigation of the effects of bread on the microbiota.

Study Type

Interventional

Enrollment (Estimated)

40

Phase

  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact Backup

Study Locations

  • France
    • Île-de-France Region
      • Bobigny, Île-de-France Region, France, 93000
        • Not yet recruiting
        • Centre de Recherche sur Volontaires (CRV)
        • Contact:
        • Principal Investigator:
          • Fabien Wuestenberghs

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

Yes

Description

Inclusion Criteria:

  • Normal weight (18 < BMI < 25 kg.m-2)
  • Male or female
  • 18 to 65 years old
  • Adults reporting intolerance to "conventional" bread
  • Absence of celiac disease
  • Affiliated to a social security scheme
  • Free, informed and express consent

Exclusion Criteria:

  • People under protective supervision: legal guardianship, tutorship or curatorship
  • People with eating disorders (anorexia, bulimia, binge eating)
  • Any known food allergy
  • Women who are pregnant or potentially pregnant (based on a positive urine pregnancy test at inclusion)
  • Breastfeeding women
  • Alcohol abuse (>2 drinks/day). At the time of inclusion, the investigator will assess whether the participant exhibits harmful alcohol consumption
  • Untreated hypertension, uncontrolled diabetes, or diseases of the digestive tract (excluding functional intestinal disorders), liver, kidneys, or severe heart disease. The investigator will assess the presence of these conditions on standard clinical criteria and the participants' self-reported medical history at the time of inclusion
  • Participation in a clinical study in the three months preceding the study
  • Absence of express consent

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: N/A
  • Interventional Model: Single Group Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: Artisanal Bread

"Artisanal" bread is made with wholemeal flour (ash = 1.50% of dry matter) from an ancient durum wheat (Russello variety) and leavened with sourdough.

"Artisanal" bread contains 6.8g of gluten and less than 1g of frutans per 100g.
Dietary supplement: Artisanal Bread

During the second part of the study (from Day 1 [D1] to Day 14 [D14]), participants will consume the "artisanal" bread on a daily basis.

Dose: D1 = 75g; D2 = 100g; from D3 to D14: 125g/day On D0 and D15, volunteers will come to the hospital for 3 hours of postprandial testing.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Intensity of gastrointestinal symptoms
Time Frame: Scores at Day 0 [D0] and Day 15 [D15]

The severity of gastrointestinal symptoms will be assessed using a score from the modified GSRS-IBS questionnaire used in this study.

This score consists of 13 questions ranging from 1 (Not at all) to 7 (Very severely) on a Likert scale. Thus, the total score can range from 13 to 91, with higher scores indicating more severe gastrointestinal symptoms and, consequently, lower tolerance.

The scores obtained before and after the diet including the "artisanal" bread will be compared.
Scores at Day 0 [D0] and Day 15 [D15]

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Intensity of gastrointestinal and extraintestinal symptoms
Time Frame: Scores at Day 0 [D0] and Day 15 [D15]

The intensity of gastrointestinal and extra-intestinal symptoms will be assessed using the total score of the modified version of the GSRS-IBS questionnaire.

Scores obtained before and after the diet including the "artisanal" bread will be compared.

The score is measured on a 7-point Likert scale, ranging from 1 (Not at all) to 7 (Very severely). The questionnaire consists of 28 questions, so total scores can range from 28 to 196, with higher scores indicating more severe gastrointestinal and extra-intestinal symptoms and, therefore, lower tolerance.
Scores at Day 0 [D0] and Day 15 [D15]
Validity of the modified GSRS-IBS
Time Frame: Scores of the two questionnaires at Day [D0] and Day [D15]

Correlations between the scores from the GSRS-IBS and the modified GSRS-IBS used in this study will be analyzed.

The GSRS-IBS score can be obtained from the modified GSRS-IBS questionnaire. This questionnaire consists of 7-point Likert scale ranging from 1 (No discomfort at all) to 7 (Very severe discomfort) for 13 items. The total score therefore ranges from 13 to 91. An increase in this score indicates greater gastrointestinal discomfort and, consequently, lower tolerance.

The modified GSRS-IBS questionnaire comprises 28 items scored on a 7-point Likert scale, ranging from 1 (Not at all) to 7 (Very severely). Thus, the total score of this questionnaire ranges from 28 to 196. An increase in this score indicates greater gastrointestinal symptoms and, consequently, lower tolerance.

These two scores will be compared, and their correlation analyzed.
Scores of the two questionnaires at Day [D0] and Day [D15]
Comparison between volunteers' perceived tolerance of "artisanal" bread and measured tolerance
Time Frame: Scores at Day 0 [D0] and Day 15 [D15]
In addition to the intensity scores calculated for each symptom (the sum of which constitutes an objective total score), participants will give a global subjective assessment of their tolerance to the "artisanal" bread using a scale from 0 (absence of symptoms) to 10 (extremely intense symptoms). The objective and subjective scores will then be compared, and their correlation analyzed.
Scores at Day 0 [D0] and Day 15 [D15]
Clinical profile of response to the "artisanal" bread
Time Frame: These scores are measured at Day 0 [D0], Day 8 [D8] and Day 15 [D15].
Individual symptoms will be grouped into symptom groups (pain, reflux, indigestion, diarrhea and constipation). A score will be calculated for each groupe, and these scores will be compared.
These scores are measured at Day 0 [D0], Day 8 [D8] and Day 15 [D15].
Evaluation of intestinal permeability
Time Frame: Measured on Day D0 [D0] and Day 15 [D15]
Intestinal permeability will be assessed by measuring serum zonulin levels and the urinary lactulose/mannitol ratio.
Measured on Day D0 [D0] and Day 15 [D15]
Evaluation of intestinal inflammation
Time Frame: Serum LBP : measured on Day 0 [D0] and Day D15 [D15] Fecal calprotectin : measured in stool samples collected at Day-1 [D-1] and Day 14 [D14].
Intestinal inflammation will be assessed by measuring serum LBP and faecal calprotectin.
Serum LBP : measured on Day 0 [D0] and Day D15 [D15] Fecal calprotectin : measured in stool samples collected at Day-1 [D-1] and Day 14 [D14].
Microbiota composition
Time Frame: Determined in stool samples collected at visit 0 [V0], on Day -1 [D-1] and Day 14 [D14]

The relative abundance of bacterial genera in stool samples at the end of each diet (with and without bread) will be compared.

Stool samples will also be collected at inclusion (visit 0 [V0]) to determine the baseline microbiota and to inoculate an in vitro artificial colon model.
Determined in stool samples collected at visit 0 [V0], on Day -1 [D-1] and Day 14 [D14]
Tolerance profiles for "artisanal" bread
Time Frame: From the enrollment (visit 0 [V0]) to the end of the study (Day 15 [D15])
Exploration of tolerance profiles to "artisanal" bread without a priori, and their characterization based on clinical data (questionnaires) and biological markers (inflammation, intestinal permeability, and microbiota).
From the enrollment (visit 0 [V0]) to the end of the study (Day 15 [D15])
Postprandial glucose responses measured after consumption of the test meal ("artisanal bread")
Time Frame: Measured at 0; 0.5; 1; 1.5; 2; 2.5 and 3 hours after test meal
Blood glucose levels measured every 30 minutes for 3 hours after the test meal
Measured at 0; 0.5; 1; 1.5; 2; 2.5 and 3 hours after test meal
Postprandial insulin responses measured after consumption of the test meal ("artisanal bread")
Time Frame: Measured at 0; 0.5; 1; 1.5; 2; 2.5 and 3 hours after test meal
Blood insulin levels measured every 30 minutes for 3 hours after the test meal
Measured at 0; 0.5; 1; 1.5; 2; 2.5 and 3 hours after test meal
Substrate oxidation rates
Time Frame: Measured at 0; 0.5; 1.5 and 2.5 hours after test meal
Fat and glucose oxidation assessed by measuring respiratory exchanges using indirect calorimetry
Measured at 0; 0.5; 1.5 and 2.5 hours after test meal
H2 concentrations in exhaled air
Time Frame: Measured at 0; 0.5; 1; 1.5; 2; 2.5 and 3 hours after test meal
H2 concentration in air measured every 30 minutes for 3 hours after test meal
Measured at 0; 0.5; 1; 1.5; 2; 2.5 and 3 hours after test meal

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Institut National de Recherche pour l'Agriculture, l'Alimentation et l'Environnement

Collaborators

UMR 914 PNCA - AgroParisTech, INRA, Université Paris-Saclay

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

January 28, 2026

Primary Completion (Estimated)

December 1, 2026

Study Completion (Estimated)

June 1, 2027

Study Registration Dates

First Submitted

January 21, 2026

First Submitted That Met QC Criteria

May 4, 2026

First Posted (Actual)

May 5, 2026

Study Record Updates

Last Update Posted (Actual)

May 5, 2026

Last Update Submitted That Met QC Criteria

May 4, 2026

Last Verified

May 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • TOLERBREAD

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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