Impact of Whole Grain Rye Bread on Health (FBS)

Impact of Whole Grain Rye Bread on Modulating Microbiota-gut-brain Axis in Healthy Subjects

This randomized controlled trial aims to study how a high intake of a fibre-rich bread affects the composition and functioning of the gut microbiota in healthy subjects, and how this, in turn, impacts on the release of gut peptides, intestinal permeability, stress and cognitive performance.

Study Overview

• Status: Completed
• Conditions: Healthy Diet
• Intervention / Treatment: Dietary supplement: Whole grain bread; Dietary supplement: Control bread

Detailed Description

Healthy subjects will be recruited for a 3-week, randomized, parallel-controlled study. Subjects that are eligible to take part in the study will be blinded and randomly allocated to consume a fibre-rich bread or a control bread daily for 3 weeks. Measurements of biomarkers related to the gut-brain axis, microbiota composition and functioning, intestinal permeability, stress and cognitive functioning will be conducted on two separate test days, at baseline and after the 3 weeks intervention. On both test days (day 0 and day 21) subjects will come to the study centre after a 10 hours overnight fast and will deliver faecal samples collected at home. At the study centre, blood samples will be collected and a device for continuous assessment of autonomic nervous system response (Biopac) will be placed. Subjects will drink a multisugar solution and urine samples will be collected for gut permeability analysis. Sugar solution intake will be followed by a baseline period during which participants will rest for 30 minutes to adapt to the laboratory setting. After the baseline period, subjects will conduct a stress test and cognitive tests. Visual analogue scales (VAS) to assess momentary perceived stress levels and saliva samples will be collected before and after the stress test. The study subjects will also complete questionnaires at both visits (food frequency questionnaire, food diary, physical activity, gastrointestinal symptom rating scale, Euro Quality of Life).

• Study Type: Interventional
• Enrollment (Actual): 33
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Sweden
  • Örebro, Sweden
    • Örebro University

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

• Age 18-44 years
• Body mass index (BMI) 18,5-30 kg/m2 (normal weight or overweight)

Exclusion Criteria:

• Significant acute or chronic illness, including an inflammatory or a functional disease of gastrointestinal track and psychiatric and psychological disorders
• Anxiety or depression (according to Hospital Anxiety and Depression Scale (HADS score) and Depression Anxiety Stress Scale (DASS-21 score))
• Use of a medication that may interfere with the study (e.g. cannabis, antipsychotics, anxiolytics, antidepressants, proton-pump inhibitors)
• Abuse of alcohol or drugs (according to AUDIT score)
• Use of antibiotic medication within the past 3 months before the study
• Use of laxative or anti-diarrhoea medication within the past 3 months before the study
• Regular consumption of probiotic or prebiotic product for the past 6 weeks before the study
• A diet that may interfere with the study (such as gluten free or low-carb diet)
• Smoking
• Pregnancy or breastfeeding
• Premenopausal female with irregular or short menstruation cycle and not using hormonal contraception
• Colour blindness, dyslexia or dyscalculia
• Unable to absent from caffeine, alcohol or intense exercise for 12 hours prior measurements.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Prevention
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Double

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: High-fibre bread; Six slices (180 g) of whole grain rye bread divided over the meals during the day for 3 weeks	Dietary supplement: Whole grain bread; Consumption of high-fibre bread as a dietary supplementation
Placebo Comparator: Control bread; Six slices (180 g) of control bread containing refined wheat and oat flour divided over the meals during the day for 3 weeks	Dietary supplement: Control bread; Consumption of control bread as a dietary supplementation

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Microbiota composition baseline vs after intervention using 16S RNA gene sequencing	Difference in gut microbiota composition in faecal samples before (baseline) and after intake of six slices of bread for 3 weeks (after intervention) using 16S RNA gene sequencing	faecal samples collected before and after intake of bread for 3 weeks

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Microbiota composition whole grain rye bread vs control bread using 16S RNA gene sequencing	Difference in gut microbiota composition in faecal samples between the study arms using 16S RNA gene sequencing	faecal samples collected before and after intake of bread for 3 weeks
Concentrations of circulatory short-chain fatty acids SCFA	Difference in blood levels of SCFA between and within intervention groups after intake of bread for 3 weeks	blood samples collected before and after intake of bread for 3 weeks
Concentrations of faecal SCFA	Difference in faecal levels of SCFA between and within intervention groups after intake of bread for 3 weeks	faecal samples collected before and after intake of bread for 3 weeks
Concentrations of blood glucagon like peptide-1 (GLP-1)	Difference in blood levels of GLP-1 between and within intervention groups after intake of bread for 3 weeks	blood samples collected before and after intake of bread for 3 weeks
Concentrations of blood glucagon like peptide-2 (GLP-2)	Difference in blood levels of GLP-2 between and within intervention groups after intake of bread for 3 weeks	blood samples collected before and after intake of bread for 3 weeks
Concentrations of blood peptide YY (PYY)	Difference in blood levels of PYY between and within intervention groups after intake of bread for 3 weeks	blood samples collected before and after intake of bread for 3 weeks
Concentrations of blood gastric inhibitory polypeptide (GIP)	Difference in blood levels of GIP between and within intervention groups after intake of bread for 3 weeks	blood samples collected before and after intake of bread for 3 weeks
Concentrations of blood neuroactive peptide Y (NPY)	Difference in blood levels of NPY between and within intervention groups after intake of bread for 3 weeks	blood samples collected before and after intake of bread for 3 weeks
Concentrations of blood brain-derived neurotrophic factor (BDNF)	Difference in blood levels of BDNF between and within intervention groups after intake of bread for 3 weeks	blood samples collected before and after intake of bread for 3 weeks
Concentrations of blood cytokines	Difference in blood levels of cytokines between and within intervention groups after intake of bread for 3 weeks	blood samples collected before and after intake of bread for 3 weeks
Concentrations of blood alkylresorcinols	Difference in blood levels of alkylresorcinols between and within intervention groups after intake of bread for 3 weeks	blood samples collected before and after intake of bread for 3 weeks
Concentrations of blood lipopolysaccharide-binding protein (LBP)	Difference in blood levels of LBP between and within intervention groups after intake of bread for 3 weeks	blood samples collected before and after intake of bread for 3 weeks
Concentrations of blood soluble CD-14 (sCD-14)	Difference in blood levels of sCD-14 between and within intervention groups after intake of bread for 3 weeks	blood samples collected before and after intake of bread for 3 weeks
Concentrations of sugars in urine	Difference on intestinal permeability between and within intervention groups after intake of bread for 3 weeks measured by the excretion of sugars contained in a multi-sugar solution	urine samples collected before and after intake of bread for 3 weeks
Concentrations of saliva cortisol during stress test	Difference in saliva levels of cortisol produced during stress test between and within intervention groups after intake of bread for 3 weeks	Saliva samples collected before the stress test, after the introduction phase, directly after the acute stress phase, 5 minutes, 10-15 minutes, 60 minutes, and 75 minutes after the stress test
Concentrations of saliva alpha-amylase during stress test	Difference in saliva levels of a-amylase produced during stress test between and within intervention groups after intake of bread for 3 weeks	Saliva samples collected before the stress test, after the introduction phase, directly after the acute stress phase, 5 minutes, 10-15 minutes, 60 minutes, and 75 minutes after the stress test

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
Gastrointestinal symptoms measured by Gastrointestinal Symptom Rating Scale in Irritable Bowel Syndrome (GSRS-IBS)	Difference in the frequency and severity of gastrointestinal symptoms between and within intervention groups after the intake of bread for 3 weeks. The GSRS-IBS contains 13 self-report items rated on a 6-point Likert scale ranging from 1 (no discomfort at all) to 7 (very severe discomfort). Total scores range from 0 to 78.	3 weeks
Food habits measured by an electronic food frequency questionnaire Mealq	Survey of participants' food habits before and during the intake of bread for 3 weeks	3 weeks
Food habits measured by a Food diary	Survey of participants' food habits before and during the intake of bread for 3 weeks	3 days
Physical activity measured by the International Physical Activity Questionnaire (IPAQ)	Survey of participants' physical activities before and during the intake of bread for 3 weeks. The IPAQ contains 7 self-report questions and the categorical score is divided into 3 levels: low (less than 600 metabolic equivalent-minutes/week), moderate (at least 600 metabolic equivalent-minutes/week) or high (at least 1500 metabolic equivalent-minutes/week).	3 days
Quality of life measured by the Euro Quality of Life questionnaire	Survey of participants' well-being before and during the intake of bread for 3 weeks. It records the patient's self-rated health on a vertical visual analogue scale where the endpoints are labelled from 0 (worst imaginable health state) to 100 (best imaginable health state).	once before and after intake of bread for 3 weeks
Perceived stress measured by a Visual analog scale questionnaire	Difference in the perceived stress during a stress test between and within intervention groups after the intake of bread for 3 weeks	before the stress test, after the introduction phase, directly after the acute stress phase, 5 minutes, 10-15 minutes, 60 minutes, and 75 minutes after the stress test
Cognitive control using Eriksen flanker task (Flanker task)	Difference in cognitive control between and within intervention groups after the intake of bread for 3 weeks	once before and after intake of bread for 3 weeks
Working memory performance using a modified N-back task combined with recent-probes item-recognition task (Sternberg task)	Difference in working memory between and within intervention groups after the intake of bread for 3 weeks	once before and after intake of bread for 3 weeks
Electrocardiogram (ECG) using the Biopac system	Difference in heart rate variability during a stress test between and within intervention groups after the intake of bread for 3 weeks	once before and after intake of bread for 3 weeks
Electrodermal activity (EDA) using the Biopac system	Difference in skin conductivity during a stress test between and within intervention groups after the intake of bread for 3 weeks. Electrodes to measure EDA will be placed on the subjects' left palm. Skin conductivity measures will include skin conductivity level (SCL), the number of skin conductivity responses (SCR), and the amplitude of SCR.	once before and after intake of bread for 3 weeks

Collaborators and Investigators

• Sponsor: Örebro University, Sweden
• Investigators: Principal Investigator: Rebecca Wall, PhD, Örebro University, Sweden

Study record dates

Study Major Dates

• Study Start (Actual): March 3, 2021
• Primary Completion (Actual): March 3, 2021
• Study Completion (Actual): November 5, 2021

Study Registration Dates

• First Submitted: February 28, 2024
• First Submitted That Met QC Criteria: March 20, 2024
• First Posted (Actual): March 27, 2024

Study Record Updates

• Last Update Posted (Actual): March 27, 2024
• Last Update Submitted That Met QC Criteria: March 20, 2024
• Last Verified: March 1, 2024

More Information

Terms related to this study

• Keywords: microbiota; dietary fibre; gut-brain axis
• Other Study ID Numbers: Dnr 2020-03709

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No