CALM Study: Can A Prebiotic Fibre bLend Improve Stress, Mood, and Anxiety? (CALM)

March 11, 2026 updated by: Myota GmbH

Can A Prebiotic Fibre bLend Improve Stress, Mood, and Anxiety? Assessing the Impact of a Daily Prebiotic Fibre Blend on Affect, Inflammation, and the Gut Microbiome: a 12-week Double-blind Placebo-controlled RCT

This clinical trial will investigate whether a powdered prebiotic fibre blend can improve perceived stress levels in healthy adults with mild-severe stress levels.

Study Overview

Status

Recruiting

Conditions

Intervention / Treatment

Detailed Description

There is growing interest in how the gut microbiota interacts with the brain to influence psychological outcomes, particularly stress. Even in otherwise healthy individuals, persistent psychological stress is associated with measurable physiological changes-including elevated cortisol levels, heightened hypothalamic-pituitary-adrenal (HPA) axis reactivity, and systemic low-grade inflammation. These biological signatures are increasingly understood to be shaped, in part, by the composition and activity of the gut microbiota.

In this study, we're investigating how a powdered prebiotic fibre supplement can improve stress levels. You may have heard people refer to this as the 'gut-brain axis'. We'll also be looking at the link between the prebiotic fibre supplement intake and changes in other areas of health, like depression, mood, anxiety, cognition, inflammation, and the gut microbiome.

Study Type

Interventional

Enrollment (Estimated)

156

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 Locations

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

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • Aged 18-50 years of age
  • Capacity to give informed consent to participate in the study
  • Able to comply with study requirements and visits
  • Meet the range required for mild-severe stress levels (as assessed by DASS-42 stress subscale)
  • Normal or corrected to normal vision and/or hearing

Exclusion Criteria:

  • Current smoker
  • Having food allergies and/or intolerances
  • Diagnosis of Type 1 or 2 diabetes or cardiovascular disease or psychiatric or neurological conditions (e.g. schizophrenia, dementia) including eating disorders
  • Current or previous diagnosis of depression in past 6 months
  • Receiving medications that lower cholesterol, blood pressure, blood glucose levels, or improve insulin sensitivity
  • Receiving antidepressant or anti-anxiety medications or treatments
  • Receiving hormonal birth control
  • Perimenopause or menopause
  • Pregnancy, lactation, or an intent to become pregnant during the course of the study
  • Continuous antibiotic use for > 3 days within 1 month prior to enrolment
  • Continuous use of weight-loss drug for > 1 month before screening
  • Major change in dietary intake in past month (e.g. excluding whole food groups)
  • Currently consuming daily prebiotic or probiotic supplements
  • Prior use (< 6 months) of any blood glucose or cholesterol lowering medication
  • Any significant GI condition affecting GI absorption including (but not limited to) inflammatory bowel disease, weight loss surgery, irritable bowel disease.
  • End stage renal disease
  • Active cancer, or treatment for any cancer, in last 3 years
  • Consuming more than 20g of fibre a day as assessed by the 18-item FiberScreen

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: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: Quadruple

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: Prebiotic fibre blend
Prebiotic fibre blend, consisting of 10g of a powdered supplement, to be taken daily alongside usual diet for 12 weeks.
Dietary supplement: Prebiotic fibre blend
A blend of prebiotic fibres in a powdered supplement form.
Placebo Comparator: Placebo
Placebo will be 10g of maltodextrin powder, to be taken daily alongside usual diet for 12 weeks.
Dietary supplement: Maltodextrin powder
Maltodextrin powder

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Perceived Stress
Time Frame: Baseline and 12 weeks
The primary objective is to determine the effect of 12-week long daily administration of Prebiotic fibre blend as compared to Placebo on stress scores (Perceived Stress Scale) on a scale between 0 - 40 (where higher scores indicate higher stress).
Baseline and 12 weeks

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Perceived Stress
Time Frame: Baseline and 8 weeks
To determine the effect of 12-week long daily administration of Prebiotic fibre blend as compared to Placebo on stress scores (Perceived Stress Scale) on a scale between 0 - 40 (where higher scores indicate higher stress).
Baseline and 8 weeks
Depression
Time Frame: Baseline, 8 weeks, and 12 weeks
To determine the effect of 12-week daily administration of Prebiotic fibre blend as compared to Placebo on depression scores (DASS-42), on a scale between 0 - 21 (where higher scores mean higher depression).
Baseline, 8 weeks, and 12 weeks
Mood
Time Frame: Baseline, 8 weeks and 12 weeks
To determine the effect of 12-week daily administration of Prebiotic fibre blend as compared to Placebo on mood scores (PANAS-X), on a scale between 10 - 50 (where higher scores on the Positive Affect scale indicate higher levels of positive engagement with your environment; while higher scores on the Negative Affect scale indicate higher levels of negative engagement).
Baseline, 8 weeks and 12 weeks
Anxiety
Time Frame: Baseline, Week 8, and Week 12
To determine the effect of 12-week daily administration of Prebiotic fibre blend as compared to Placebo on anxiety scores (DASS-42), on a scale between 0 - 21 (where higher scores mean higher anxiety levels).
Baseline, Week 8, and Week 12
Serum hs-CRP
Time Frame: Baseline and Week 12
To determine the effect of 12-week daily administration of Prebiotic fibre blend as compared to Placebo on serum high sensitivity C-Reactive Protein (hs-CRP).
Baseline and Week 12
Gastrointestinal symptoms
Time Frame: Baseline, Week 8, and Week 12
To determine the effect of 12-week daily administration of Prebiotic fibre blend as compared to Placebo on gastrointestinal symptoms (GSRS), on a scale of 15 - 105 where higher scores indicate more severe gastrointestinal discomfort.
Baseline, Week 8, and Week 12
Cognition: Emotional Stroop
Time Frame: Baseline and Week 12
To determine the effect of 12-week daily administration of Prebiotic fibre blend as compared to Placebo on emotional interference in attention and processing (reaction time and accuracy), as assessed by the Emotional Stroop where better scores are achieved by lower reaction times and higher accuracy score.
Baseline and Week 12
Cognition: Affective 2-Back Task
Time Frame: Baseline and Week 12
To determine the effect of 12-week daily administration of Prebiotic fibre blend as compared to Placebo on emotional interference in working memory under emotional load, as assessed by the Affective 2-Back Task, where better scores are achieved by lower reaction times and higher accuracy score.
Baseline and Week 12
Cognition: Emotional Go-No-Go
Time Frame: Baseline and Week 12
To determine the effect of 12-week daily administration of Prebiotic fibre blend as compared to Placebo on emotion-related inhibitory control and response suppression, as assessed by the Emotional Go-No-Go, where better scores are achieved by higher correct response rates and lower commission errors.
Baseline and Week 12
Cognition: Number-Letter Task
Time Frame: Baseline and Week 12
To determine the effect of 12-week daily administration of Prebiotic fibre blend as compared to Placebo on cognitive flexibility and task-switching ability, as assessed by the Number-Letter Task, where better scores are achieved by higher numbers of correctly recalled items.
Baseline and Week 12
Cognition: Attentional Network Task
Time Frame: Baseline and Week 12
To determine the effect of 12-week daily administration of Prebiotic fibre blend as compared to Placebo on efficiency of alerting, orienting, and executive attention networks, as assessed by the Attentional Network Task , where better scores are achieved by lower reaction times and higher accuracy.
Baseline and Week 12

Other Outcome Measures

Outcome Measure
Measure Description
Time Frame
Sleep Quality
Time Frame: Baseline and Week 12
To determine the effect of 12-week daily administration of Prebiotic fibre blend as compared to Placebo on sleep quality (PSQI), on a scale of 0 - 21 where higher scores indicate worse sleep.
Baseline and Week 12
Quality of Life Index
Time Frame: Baseline And Week 12
To determine the effect of 12-week daily administration of Prebiotic fibre blend as compared to Placebo on quality of life index (WHOQOL), on a scale of 0 -100 where higher scores indicate higher quality of life.
Baseline And Week 12
Serum LDL Cholesterol
Time Frame: Baseline and Week 12
To determine the effect of 12-week daily administration of Prebiotic fibre blend as compared to Placebo on serum LDL cholesterol.
Baseline and Week 12
Serum HDL Cholesterol
Time Frame: Baseline and Week 12
To determine the effect of 12-week daily administration of Prebiotic fibre blend as compared to Placebo on serum HDL cholesterol.
Baseline and Week 12
Serum Triglycerides
Time Frame: Baseline and Week 12
To determine the effect of 12-week daily administration of Prebiotic fibre blend as compared to Placebo on serum triglycerides.
Baseline and Week 12
Total cholesterol
Time Frame: Baseline and Week 12
To determine the effect of 12-week daily administration of Prebiotic fibre blend as compared to Placebo on serum total cholesterol.
Baseline and Week 12
Waist to hip ratio
Time Frame: Baseline and Week 12
To determine the effect of 12-week daily administration of Prebiotic fibre blend as compared to Placebo on waist to hip ratio.
Baseline and Week 12
Waist circumference
Time Frame: Baseline and Week 12
To determine the effect of 12-week daily administration of Prebiotic fibre blend as compared to Placebo on waist circumference (cm).
Baseline and Week 12
Gut microbiome composition
Time Frame: Baseline and Week 12
To determine the effect of 12-week daily administration of Prebiotic fibre blend as compared to Placebo on gut microbiome diversity scores (alpha and beta measures) and composition (differential abundance testing).
Baseline and Week 12
Systolic blood pressure
Time Frame: Baseline and Week 12
To determine the effect of 12-week daily administration of Prebiotic fibre blend as compared to Placebo on systolic blood pressure (mmHg).
Baseline and Week 12
Diastolic blood pressure
Time Frame: Baseline and Week 12
To determine the effect of 12-week daily administration of Prebiotic fibre blend as compared to Placebo on diastolic blood pressure (mmHg).
Baseline and Week 12
BMI
Time Frame: Baseline and Week 12
To determine the effect of 12-week daily administration of Prebiotic fibre blend as compared to Placebo on BMI (kg/m2).
Baseline and Week 12
Exploratory endpoint
Time Frame: Baseline, Week 8, and Week 12
Inter-dependencies between primary and secondary outcomes will be assessed.
Baseline, Week 8, and Week 12

Collaborators and Investigators

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

Sponsor

Myota GmbH

Collaborators

University of Reading

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)

October 2, 2025

Primary Completion (Estimated)

September 30, 2026

Study Completion (Estimated)

December 30, 2026

Study Registration Dates

First Submitted

August 14, 2025

First Submitted That Met QC Criteria

September 23, 2025

First Posted (Actual)

October 1, 2025

Study Record Updates

Last Update Posted (Actual)

March 13, 2026

Last Update Submitted That Met QC Criteria

March 11, 2026

Last Verified

March 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • CALM

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

IPD Plan Description

Participant data will not be shared.

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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