Investigation of the Mechanisms of the Gut-brain Axis in Binge Eating and Obesity. (Gut2Brain)

Gut2Brain: Investigation of the Mechanisms of the Gut-brain Axis in Binge Eating and Obesity

Binge Eating Disorder (BED) is a recently recognized eating disorder, characterized by recurrent episodes of overeating with a loss of control. Highly comorbid with obesity, BED is associated with poor outcomes in weight loss treatments and presents unique challenges due to its distinct neuro-psycho-biological mechanisms, which remain poorly understood. The Microbiota-Gut-Brain Axis (MGBA) is a bidirectional communication system linking the gut microbiota with the central nervous system, that plays a critical role in regulating appetite, mood, and eating behavior. Dysregulations in MGBA may contribute to the development and maintenance of BED, offering a novel framework for understanding its complex mechanisms and identifying new therapeutic targets. Psychobiotics -pre-, pro-, or symbiotics that modulate the microbiota- emerge as a promising treatment strategy to address BED symptoms by influencing MGBA activity.

The goal of this randomized clinical trial (RCT) is to investigate the role of psychobiotics in modulating the gut-brain axis and improving binge eating in adults, with a particular focus on evaluating these effects independently of obesity status. This project stands out for its comprehensive approach to understanding BED, integrating psychological, neurofunctional, hormonal, and microbiota factors that contribute to this complex disorder.

The main questions it aims to answer are:

• What specific alterations in the MGBA pathways are associated with BED?
• Can psychobiotic supplementation effectively reverse microbiota alterations and modulate MGBA activity, ultimately improving BED symptoms? Researchers will compare participants receiving psychobiotics to those receiving a look-alike substance that contains no drug (a placebo) to evaluate whether psychobiotics impact endocrine hormones, neurofunction, psychological and behavioral factors related to eating regulation, and BED symptoms.

Participants will:

• Undergo an assessment protocol that includes microbiota sampling, blood tests for hormone analysis, neurofunctional evaluations, and psychological/behavioral assessments before and after the psychobiotics/ placebo intervention.
• Take psychobiotics or a placebo daily for 12 weeks and receive well-being monitoring
• Participate in follow-up visits three months after the intervention to monitor changes in BED symptoms and related parameters.

Study Overview

• Status: Not yet recruiting
• Conditions: Obesity; Binge Eating Disorder
• Intervention / Treatment: Dietary supplement: Psychobiotic treatment; Other: Placebo treatment

Detailed Description

This research project aims to investigate the role of psychobiotics in reversing MGBA alterations specific to BED. Therefore, a two-arm Randomized Clinical Trial (RCT) will be conducted. Participants will include individuals with BED and obesity, individuals with obesity only, and individuals with normal weight that will be randomly assigned to one of two groups:

i) an intervention group receiving psychobiotic supplementation ii) a control group receiving placebo supplementation. The sample size was computed considering the sample needed for 3 groups comparison in the RCT. G Power was used for (Mixed) ANOVAs considering f = 0.25, power = 90%, α = 0.05, and corr = 0.5., and 15% dropout.

At both the beginning and end of the trial, participants will undergo an assessment protocol.

Assessment protocol:

Participants will be invited to visit Braga Hospital where the assessment will take place for a scheduled appointment to undergo the assessment protocol for approximately 2 hours. The first step will involve the assessment of appetitive hormones through blood samples collected at three time points. The first blood sample (0 minutes) will be taken after a 12-hour overnight fast. Participants will consume 600 mL of a standardized liquid test meal, and additional blood draws will occur 10 and 30 minutes after the meal.

Between the second and third blood samples collected, participants will respond with some self-report measures. Specifically, self-report measures will assess socio-demographic data (age, sex, gender, education levels, marital status, and weight history) and psychological aspects: 1) emotional regulation and impulse control, distress tolerance, and positive and negative affects; 2) eating behavior, assessing eating expectancy, emotional eating, compulsive eating, and restraint eating. Then participants will do resting-state functional magnetic resonance imaging (rs-FMRI) performed to evaluate resting-state network connectivity.

Stool samples will be collected using a kit that includes all the necessary tools for proper sample collection and preparation for microbiota analysis.

The psychobiotic and the placebo package and instructions will be delivered during this scheduled appointment in Braga Hospital. All participants will be contacted weekly during the 12-week trial to ensure/increase adherence to the guidelines of prebiotic/placebo intervention.

Statistical Analyses:

Overall, multivariate analysis of variance (MANOVA) and/or general linear models (GLM) with mixed-model repeated measures will be used to examine group differences related to MGBA mechanisms, as well as significant main effects and interaction effects between baseline (T0) and the end of the RCT (T1). Structural equation modeling (SEM) will be employed to evaluate MGBA mechanisms as mediators of the changes observed between T0 and T1.

• Study Type: Interventional
• Enrollment (Estimated): 104
• Phase: Phase 1

Contacts and Locations

• Study Contact: Name: Eva M. Conceição; Phone Number: +351 917 853 236; Email: econceicao@fpce.up.pt
• Study Contact Backup: Name: Catarina C. Gomes; Phone Number: 914841706; Email: 202408503@fpce.up.pt

Study Locations

• Portugal
  • Paranhos
    • Porto, Paranhos, Portugal, 4200-135
      • Center for Psychology at University of Porto
      • Contact: Center for Psychology at University of Porto; Phone Number: +351 220 400 617; Email: cpup@fpce.up.pt

Participation Criteria

Eligibility Criteria

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

Description

Inclusion Criteria:

• Portuguese adults (25 with normal weight; 25 with obesity only (30 ≤ BMI < 40) and BED; 54 with BED)
• Residents in Portugal for the past 10 years

Exclusion Criteria:

• Significant weight loss (>5% of body weight) in the past 2 years
• Antibiotic use in the past 6 months
• History of surgery or medical/psychiatric diseases
• Pregnant or breastfeeding
• History of drug use or dependence
• Use of medications that impact weight
• Have metal implants or pacemakers

Study Plan

How is the study designed?

Design Details

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

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Psychobiotic group; An intervention group receiving a psychobiotic-a native inulin prebiotic. Native inulin extracted from chicory roots was selected as the psychobiotic since it is a mixture of short inulin molecules, which are metabolized primarily in the proximal colon and are more rapidly fermented, with longer chain ones, which are fermented later and slower in the distal colon. The psychobiotic nature of Inulin has been suggested in recent literature.	Dietary supplement: Psychobiotic treatment; The dietary supplementation will follow established guidelines, recommending an intake of 16 g of prebiotic per day, distributed across three meals, for a duration of 12 weeks.; Other Names: Inulin; Prebiotic
Placebo Comparator: Control group; A control group receiving a taste/appearance-matched placebo- the maltodextrin. Maltodextrin is a carbohydrate consisting of short chains of glucose molecules. It is commonly used as a placebo in clinical trials, providing no significant health benefits or harm when consumed with moderation.	Other: Placebo treatment; The control group will receive identical packaging that matches the experimental treatment in taste and appearance and will follow the same guidelines for consuming the placebo. For ethical reasons, after the end of the RCT, the control group will be given the option to receive the same prebiotic supplement.; Other Names: Maltodextrin (Placebo)

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Gut Microbiota outcomes - Gut-Bacteria Composition	Stool samples from each participant will be fermented by the prebiotic to allow direct comparison of individual alterations in vitro and in vivo of the microbiome. Changes in gut-bacteria composition and its adhesion into the mucus layer will be analyzed.	Change measures: baseline and end of treatment at 12 weeks
Gut Microbiota outcomes - Molecules released by the gut-bacteria	Stool samples from each participant will be fermented by the prebiotic to allow direct comparison of individual alterations in vitro and in vivo of the microbiome. Molecules released by the bacteria, including short-chain fatty acids (SCFA), lipopolysaccharides (LPS), gamma-aminobutyric acid (GABA), dopamine, and serotonin, which modify host metabolism and central regulation of appetite directly via vagal stimulation or indirectly through immune-neuroendocrine mechanisms, will be traced during fermentations.	Change measures: baseline and end of treatment at 12 weeks
Psycho-behavioral outcomes - Three Factor Eating Questionnaire-21	Three Factor Eating Questionnaire-21 (TFEQ-21): assesses psychopathology and behaviors related to eating disorders, generating 3 subscales: emotional eating; compulsive eating; restraint eating.	Change measures: baseline, end of treatment at 12 weeks and follow-up at 12 weeks post-treatment.
Psycho-behavioral outcomes - Eating Expectancy Inventory	- The Eating Expectancy Inventory (EEI): evaluates cognitive expectations regarding eating	Change measures: baseline, end of treatment at 12 weeks and follow-up at 12 weeks post-treatment.
Psycho-behavioral outcomes - Negative urgency subscale	Negative urgency subscale from the Urgency, Premeditation, Perseverance, and Sensation Seeking scales (UPPS): assesses the tendency to act rashly/impulsively when experiencing negative emotions.	Change measures: baseline, end of treatment at 12 weeks and follow-up at 12 weeks post-treatment.
Psycho-behavioral outcomes - Difficulties in Emotion Regulation Scale	Difficulties in Emotion Regulation Scale (DERS): self-report measure developed to assess difficulties in emotional dysregulation.	Change measures: baseline, end of treatment at 12 weeks and follow-up at 12 weeks post-treatment.
Psycho-behavioral outcomes - Distress Tolerance Scale	The Distress Tolerance Scale (DTS): scale that assesses ability to experience, tolerate, and function in a context of emotional distress	Change measures: baseline, end of treatment at 12 weeks and follow-up at 12 weeks post-treatment.
Neurofunctioning outcomes - Default mode network	Neurofunctioning will be assessed through rs-fMRI. Specifically, we aim to compare the resting-state networks (RSNs), such as the default mode network (DMN), the salience network (SN), the meso/paralimbic network (MPN), and the executive network (EN) across the three groups. The DMN is involved in self-referential processing, which includes monitoring the external environment as well as physical and emotional states.	Change measures: baseline and end of treatment at 12 weeks
Neurofunctioning outcomes - Salience network	Neurofunctioning will be assessed through rs-fMRI. Specifically, we aim to compare the resting-state networks (RSNs), such as the default mode network (DMN), the salience network (SN), the meso/paralimbic network (MPN), and the executive network (EN) across the three groups. The DMN is involved in self-referential processing, which includes monitoring the external environment as well as physical and emotional states. The SN is involved in detecting the salience of stimuli, integrating emotional arousal, food, and reward processing.	Change measures: baseline and end of treatment at 12 weeks
Neurofunctioning outcomes - Meso/Paralimbic network	Neurofunctioning will be assessed through rs-fMRI. Specifically, we aim to compare the resting-state networks (RSNs), such as the default mode network (DMN), the salience network (SN), the meso/paralimbic network (MPN), and the executive network (EN) across the three groups. The MPN is involved in processing emotional information and interoceptive awareness.	Change measures: baseline and end of treatment at 12 weeks
Neurofunctioning outcomes - Executive network	Neurofunctioning will be assessed through rs-fMRI. Specifically, we aim to compare the resting-state networks (RSNs), such as the default mode network (DMN), the salience network (SN), the meso/paralimbic network (MPN), and the executive network (EN) across the three groups. The EN is involved in cognitive control and inhibitory processes, such as the termination of food consumption	Change measures: baseline and end of treatment at 12 weeks
Appetitive hormones outcomes - Ghrelin	Assessment of appetitive hormones that modulate eating behavior: Ghrelin is an orexigenic hormone with stimulatory effects on appetite and food intake.	Change measures: baseline and end of treatment at 12 weeks
Appetitive hormones outcomes - Glucagon-Like Peptide 1	Assessment of appetitive hormones that modulate eating behavior: Glucagon-Like Peptide 1 (GLP-1) have an anorexigenic effect and are thought to contribute to impaired satiation and binge eating tendencies. GLP-1 has been the target of novel therapeutics for weight loss, but few studies have examined its impact on BED.	Change measures: baseline and end of treatment at 12 weeks
Appetitive hormones outcomes - Peptide YY	Assessment of appetitive hormones that modulate eating behavior: - Peptide YY (PYY) have an anorexigenic effect and are thought to contribute to impaired satiation and binge eating tendencies.	Change measures: baseline and end of treatment at 12 weeks
Appetitive hormones outcomes - Leptin	Assessment of appetitive hormones that modulate eating behavior: Leptin acts as a regulatory signal reflecting the adipose tissue stores. Both insufficiency and resistance to its actions promote hunger and increased food intake. Leptin can decrease food reward and act in the central nervous system as regulators of energy homeostasis.	Change measures: baseline and end of treatment at 12 weeks
Appetitive hormones outcomes - Insulin	Assessment of appetitive hormones that modulate eating behavior: Insulin can decrease food reward and act in the central nervous system as regulators of energy homeostasis.	Change measures: baseline and end of treatment at 12 weeks
Appetitive hormones outcomes - Cortisol	Assessment of appetitive hormones that modulate eating behavior: - Cortisol is responsible for the stress response, acting on the hypothalamic-pituitary axis, and it is associated with increased eating	Change measures: baseline and end of treatment at 12 weeks

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Eating Disorder Examination	Eating Disorder Examination (EDE): semi-structured clinical interview for the diagnosis of binge eating disorder	baseline moment

Collaborators and Investigators

• Sponsor: Universidade do Porto
• Collaborators: University of Minho; Braga Hospital
• Investigators: Principal Investigator: Eva M. Conceição, Center for Psychology at University of Porto (CPUP); Principal Investigator: Clarisse N. Salomé, Center for Engineering Biological (CEB) at University of Minho

Study record dates

Study Major Dates

• Study Start (Estimated): April 1, 2025
• Primary Completion (Estimated): September 1, 2028
• Study Completion (Estimated): March 1, 2030

Study Registration Dates

• First Submitted: January 17, 2025
• First Submitted That Met QC Criteria: February 6, 2025
• First Posted (Actual): March 25, 2025

Study Record Updates

• Last Update Posted (Actual): March 28, 2025
• Last Update Submitted That Met QC Criteria: March 24, 2025
• Last Verified: March 1, 2025

More Information

Terms related to this study

• Keywords: Obesity; Binge eating disorder; psychobiotic treatment; Study of neuro-psycho-biological mechanisms; Microbiota-Gut-Brain Axis (MGBA)
• Additional Relevant MeSH Terms: Mental Disorders; Nutrition Disorders; Overnutrition; Body Weight; Hyperphagia; Signs and Symptoms, Digestive; Overweight; Bulimia; Obesity; Binge-Eating Disorder; Feeding and Eating Disorders
• Other Study ID Numbers: UPorto_Gut2Brain

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES
• IPD Plan Description: All IPD collected throughout the trial.
• IPD Sharing Time Frame: from jan 2030 to jan 2035
• IPD Sharing Access Criteria: Researcher with research track record in the filed by contacting the PI of the study.
• IPD Sharing Supporting Information Type: STUDY_PROTOCOL; SAP; ICF

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: No