Skip to main content
OpenTrials
Recruiting

NCT Number: NCT07201909

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

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

Recruiting

Interested in participating?

Request Info

Key information

Conditions

Stress Anxiety Disorders Behavior Behavioral Symptoms Depression Inflammation Mental Disorders Pathologic Processes Pathological Conditions, Signs and Symptoms

Age range

18 year–50 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

CALM Study Site

London, EC2A 4BQ, United Kingdom

Location status: Recruiting

Location contact

Caitlin Hall, PhD

CONTACT

[email protected]

07830709854

About this study

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.

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

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

Treatment and study plan

Prebiotic fibre blend

Dietary Supplement

A blend of prebiotic fibres in a powdered supplement form.

Maltodextrin powder

Dietary Supplement

Maltodextrin powder

Primary outcomes

  1. 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).

Secondary outcomes

  1. 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).

  2. 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).

  3. 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).

  4. 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).

  5. 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).

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

Other outcomes

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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).

  9. 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).

  10. 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).

  11. 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).

  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).

  13. Exploratory endpoint

    Time frame: Baseline, Week 8, and Week 12

    Inter-dependencies between primary and secondary outcomes will be assessed.

Study contacts

Contact information is provided by the study sponsor or research team.

Caitlin Hall, PhD, RD

CONTACT

[email protected]

07830709854

Sponsors and collaborators

Lead sponsor

Myota GmbH

Industry

Collaborators

  • University of Reading

Registry information

Official study title

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

Acronym: CALM

Important dates

Study start
2025
Primary completion
2026
Study completion
2026
First posted
Oct 1, 2025
Registry last updated
Mar 13, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

Related clinical trials

Published trials that share one or more normalized conditions with this study.