The Effects of Postbiotic Supplementation in Female Athletes (GIJane)

May 29, 2026 updated by: SPSKJOHN@ljmu.AC.UK, Liverpool John Moores University

The Effect of Daily Supplementation With Humiome® Post LB on Gastrointestinal Symptoms in Female Athletes. A Double-blinded Randomised Controlled Trial.

The goal of this clinical trial is to learn if a postbiotic supplement can reduce stomach and gut symptoms in physically active women.

The main questions it aims to answer are:

Does the supplement reduce gut symptoms during the menstrual cycle? Does it improve symptoms related to exercise?

Researchers will compare the postbiotic supplement to a placebo (a look-alike capsule that contains no active ingredient) to see if the supplement works.

Participants will be physically active, premenopausal female athletes.

Participants will:

Take either the postbiotic supplement or a placebo each day for two menstrual cycles Track their menstrual cycle and training Report gut symptoms using regular questionnaires Provide stool samples to assess gut health

This study will help researchers understand whether postbiotic supplements can improve gut health and reduce symptoms that may affect training and performance in female athletes.

Study Overview

Status

Recruiting

Conditions

Intervention / Treatment

Detailed Description

Female athletes commonly report gastrointestinal (gut) symptoms, particularly during exercise and at certain phases of the menstrual cycle. These symptoms can negatively affect comfort, training, and performance. Despite this, there is limited research examining strategies to reduce these symptoms in physically active women.

Postbiotics are non-living microbial products that may support gut health by improving the function of the gut barrier and influencing the gut microbiota. While previous research suggests that similar products may reduce gut symptoms in clinical and general populations, their effects in female athletes, particularly across the menstrual cycle, are not well understood.

This study is a randomized, placebo-controlled clinical trial designed to investigate the effects of daily postbiotic supplementation on gut symptoms in physically active, premenopausal female athletes. Participants will be randomly assigned to receive either a postbiotic supplement (Humiome® Post LB) or a placebo for two consecutive menstrual cycles.

Throughout the study, participants will record gut symptoms using validated questionnaires, with a focus on symptoms experienced during menstruation and across the menstrual cycle. Additional measures will include subtypes of gut symptoms (such as abdominal pain, diarrhoea, and constipation), training behaviour, and stool samples to assess gut microbiota composition and diversity.

The primary aim is to determine whether postbiotic supplementation reduces overall gut symptom severity during menstruation compared to placebo. Secondary analyses will explore changes in specific symptom types, gut microbiota outcomes, and training-related measures.

This research will provide new insight into the role of postbiotic supplementation in supporting gut health in female athletes and may help inform strategies to reduce symptoms that can impact training and performance.

Study Type

Interventional

Enrollment (Estimated)

100

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

  • United Kingdom
    • Merseyside
      • Liverpool, Merseyside, United Kingdom, L3 3AF
        • Recruiting
        • Tom Reilley Building
        • Contact:
        • Contact:
        • Sub-Investigator:
          • Samanvita Ravikanti, PhDc
        • Sub-Investigator:
          • Maxine Gaivizo, BSc

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:

  1. Female, cisgender, premenopausal.
  2. Minimum age 18 years.
  3. Regular, natural menstrual cycle (21-35 days in duration), with 9 or more consecutive periods per year, if possible documented with tracker apps, calendars, or other tools
  4. Ability to give informed consent.
  5. Body mass index (BMI) ≥ 18.5 and < 24.9 kg/m²
  6. Agreeing to maintain lifestyle habits during the study (same dietary and physical activity habits)
  7. Having a smartphone and a history of consistent tracking of training and health records via apps.
  8. Having regular GI issues during exercise, and during menstruation. During pre-screening, this will be assessed with a shortened GSRS questionnaire, where participants need to have had, in the month preceding pre-screening, the equivalent of at least a score of 2 in a GSRS focus area (diarrhoea, pain, indigestion).
  9. No relevant self-reported abnormalities from medical history.
  10. Trained athlete (trains at least 3 times per week for more than 1 hour per day and who has been involved in endurance training for at least 2 years in alignment with previous research (Pfeiffer et al., 2010). This will be evaluated by assessing training records (Strava or similar applications, certificates of attendance at athletic events, club membership, etc.).
  11. Access to a health-care provider, who can be contacted by the CRO, and who reside in areas with available emergency health services.

Exclusion Criteria:

  1. Individuals who are pregnant, lactating, or plan to become pregnant before study end.
  2. Individuals with secondary amenorrhea.
  3. Individuals who use hormonal contraceptives during the last 6 months before (and during) the trial.
  4. Individuals who are currently participating in another clinical trial or have participated in a trial within the last two months prior to enrolment.
  5. Tobacco smokers and vapers.
  6. Individuals with acute illnesses.
  7. Individuals with a current musculoskeletal injury or one within the last month.
  8. Individuals taking probiotic supplements or have taken probiotics two weeks prior to enrolment.
  9. Individuals controlling chronic diseases with treatments known to alter the intestinal microbiome or to alter GI symptoms, such as certain pain killers, antacids, proton pump inhibitors, anti-diarrhoeal medication or supplements, and laxatives.
  10. Individuals having received antibiotics treatments within three months of trial start.
  11. Individuals having planned major changes in lifestyle (i.e. diet, weight loss program, exercise level, travelling) during the duration of the study.
  12. Individuals who have hypersensitivity/allergy to any of the components of the test product.
  13. Individuals who have planned major elective surgery during the study period.

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: Triple

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: Postbiotic Supplementation
All participants complete a one menstrual cycle placebo run-in phase before randomisation. Participants in this arm then receive the postbiotic supplement daily for two consecutive menstrual cycles.
Dietary supplement: Postbiotic
Postbiotic supplement (Humiome® Post LB) administered as two oral capsules daily, providing 340 mg of postbiotic per day. The supplement contains heat-inactivated microbial strains and fermentation products. Participants will take the supplement daily for two consecutive menstrual cycles following a one-cycle placebo run-in phase.
Dietary supplement: Placebo
Placebo capsules containing microcrystalline cellulose, matched in appearance to the postbiotic supplement. Participants will take two capsules daily during a one-cycle placebo run-in phase and, if randomized to the placebo group, continue for two additional menstrual cycles.
Placebo Comparator: Placebo
All participants complete a one menstrual cycle placebo run-in phase before randomisation. Participants in this arm then continue taking placebo daily for two consecutive menstrual cycles.
Dietary supplement: Placebo
Placebo capsules containing microcrystalline cellulose, matched in appearance to the postbiotic supplement. Participants will take two capsules daily during a one-cycle placebo run-in phase and, if randomized to the placebo group, continue for two additional menstrual cycles.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Gastrointestinal Symptom Severity During Menstruation
Time Frame: At the post menstruation assessment following completion of cycle 4 ~84-147 days depending on individual cycle and menstruation duration
To assess the effect of daily consumption of Humiome® Post LB (HPLB) on menstrual cycle-related gastrointestinal symptoms (total amended Gastrointestinal Symptom Rating Scale scores; aGSRS) during the final intervention menstrual cycle (Phase 3) in physically active, premenopausal female athletes.
At the post menstruation assessment following completion of cycle 4 ~84-147 days depending on individual cycle and menstruation duration

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Total Gastrointestinal Symptom Rating Scale (GSRS) score assessed weekly across the two intervention menstrual cycles.
Time Frame: Weekly from the start of Cycle 2 through completion of Cycle 4 (up to 147 days from baseline; cycles range 21-35 days
To assess the effect of daily consumption of HPLB on menstrual cycle-related gastrointestinal symptoms (GSRS) during the second intervention menstrual cycle (Phase 2) in physically active, premenopausal female athletes, by comparing the HPLB group to the placebo group. This is a 7-point Likert scale with 1 indicating "no discomfort at all" and 7 indicating "very severe discomfort".
Weekly from the start of Cycle 2 through completion of Cycle 4 (up to 147 days from baseline; cycles range 21-35 days
Total Gastrointestinal Symptom Rating Scale Score
Time Frame: Weekly from the start of the start of the first intervention cycle (Cycle 2) through completion of the final intervention cycle (Cycle 4), up to 147 days from baseline
Between-group difference (HPLB vs placebo) in total Gastrointestinal Symptom Rating Scale (GSRS) score assessed weekly across the two intervention menstrual cycles. This is a 7-point Likert scale with 1 indicating "no discomfort at all" and 7 indicating "very severe discomfort".
Weekly from the start of the start of the first intervention cycle (Cycle 2) through completion of the final intervention cycle (Cycle 4), up to 147 days from baseline
GSRS Sub-Category Scores
Time Frame: Weekly from the start of the start of the first intervention cycle (Cycle 2) through completion of the final intervention cycle (Cycle 4), up to 147 days from baseline
Between-group difference (HPLB vs placebo) in Gastrointestinal Symptom Rating Scale (GSRS) sub-category scores assessed weekly across the two intervention menstrual cycles, including reflux, abdominal pain, indigestion, diarrhoea, and constipation. This is a 7-point Likert scale with 1 indicating "no discomfort at all" and 7 indicating "very severe discomfort".
Weekly from the start of the start of the first intervention cycle (Cycle 2) through completion of the final intervention cycle (Cycle 4), up to 147 days from baseline
Wilson Gastrointestinal Symptom Score
Time Frame: Daily during menstruation on Day 1 (±1 day) of Cycle 2 (phase 2), Cycle 3 and Cycle 4 (phase 3). Up to 147 days from baseline.
Between-group difference (HPLB vs placebo) in Wilson Gastrointestinal Symptom scores recorded daily during menstruation across both intervention cycles. Gastrointestinal symptoms will be rated on a 0-10 Likert scale for that day. The scale has descriptors of "no discomfort," "moderate discomfort," and "unbearable discomfort" at 0, 5, and 10, respectively.
Daily during menstruation on Day 1 (±1 day) of Cycle 2 (phase 2), Cycle 3 and Cycle 4 (phase 3). Up to 147 days from baseline.
Faecal microbial composition
Time Frame: Menstruation on Day 1 (±1 day) of Cycle 2 (phase 2) and Cycle 4 (phase 3). Approximately 28-140 days from baseline depending on individual menstrual cycle duration.
Between-group difference (HPLB vs placebo) in faecal microbial composition at phylum, genus, and species level measured using metagenomic sequencing.
Menstruation on Day 1 (±1 day) of Cycle 2 (phase 2) and Cycle 4 (phase 3). Approximately 28-140 days from baseline depending on individual menstrual cycle duration.
Faecal Microbial Diversity
Time Frame: Menstruation on Day 1 (±1 day) of Cycle 2 (phase 2) and Cycle 4 (phase 3). Approximately 28-140 days from baseline depending on individual menstrual cycle duration.
Between-group difference (HPLB vs placebo) in faecal microbial diversity at species level measured using metagenomic sequencing.
Menstruation on Day 1 (±1 day) of Cycle 2 (phase 2) and Cycle 4 (phase 3). Approximately 28-140 days from baseline depending on individual menstrual cycle duration.
Faecal Microbial Metabolites
Time Frame: Menstruation on Day 1 (±1 day) of Cycle 2 (phase 2) and Cycle 4 (phase 3). Approximately 28-140 days from baseline depending on individual menstrual cycle duration.
Between-group difference (HPLB vs placebo) in faecal microbial metabolites, including short-chain fatty acids.
Menstruation on Day 1 (±1 day) of Cycle 2 (phase 2) and Cycle 4 (phase 3). Approximately 28-140 days from baseline depending on individual menstrual cycle duration.
Adherence to Planned Training
Time Frame: Weekly from the start of the first intervention cycle (Cycle 2) through completion of the final intervention cycle (Cycle 4), up to 147 days from baseline.
Between-group difference (HPLB vs placebo) in adherence to physical activity training schedules, measured as the percentage of planned training sessions completed across the two intervention menstrual cycles.
Weekly from the start of the first intervention cycle (Cycle 2) through completion of the final intervention cycle (Cycle 4), up to 147 days from baseline.
Weekly Duration of Physical Training
Time Frame: Weekly from the start of the first intervention cycle (Cycle 2) through completion of the final intervention cycle (Cycle 4), up to 147 days from baseline.
Between-group difference (HPLB vs placebo) in average weekly minutes of physical training completed across the two intervention menstrual cycles.
Weekly from the start of the first intervention cycle (Cycle 2) through completion of the final intervention cycle (Cycle 4), up to 147 days from baseline.
Weeks With Moderately Severe or Worse Gastrointestinal Symptoms
Time Frame: Weekly across the two intervention menstrual cycles
Between-group difference (HPLB vs placebo) in the number of weeks with moderately severe or worse gastrointestinal symptoms, defined as a GSRS score of 4 or higher in any of the five symptom categories: reflux, abdominal pain, indigestion, diarrhoea, or constipation.
Weekly across the two intervention menstrual cycles
Gastrointestinal-Symptom-Free Weeks
Time Frame: Weekly cross the two intervention menstrual cycles
Between-group difference (HPLB vs placebo) in the number of gastrointestinal-symptom-free weeks, defined as a GSRS score of 1 in all five symptom categories: reflux, abdominal pain, indigestion, diarrhoea, and constipation.
Weekly cross the two intervention menstrual cycles

Collaborators and Investigators

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

Sponsor

Liverpool John Moores University

Investigators

  • Principal Investigator: Kelsie Johnson, PhD, Liverpool John Moores University

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

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)

May 5, 2026

Primary Completion (Estimated)

March 30, 2027

Study Completion (Estimated)

May 30, 2027

Study Registration Dates

First Submitted

April 22, 2026

First Submitted That Met QC Criteria

May 5, 2026

First Posted (Actual)

May 12, 2026

Study Record Updates

Last Update Posted (Actual)

June 2, 2026

Last Update Submitted That Met QC Criteria

May 29, 2026

Last Verified

May 1, 2026

More Information

Terms related to this study

Other Study ID Numbers

  • 25/SPS/057_2026

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

YES

IPD Plan Description

De-identified individual participant data that underlie the results reported in this study will be made available upon reasonable request to the principal investigator following publication.

IPD Sharing Time Frame

Data will be available following publication for a period of up to 5 years.

IPD Sharing Access Criteria

Data will be available to researchers who provide a methodologically sound proposal, subject to approval by the principal investigator. Requests should be directed to the principal investigator.

IPD Sharing Supporting Information Type

  • STUDY_PROTOCOL
  • CSR

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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