RecruitingNAINTERVENTIONAL

The Effects of Postbiotic Supplementation in Female Athletes

This study is for physically active women who often have tummy and gut problems, especially during their periods or when exercising. Researchers want to see if a daily supplement called a postbiotic can help reduce these issues. Participants will take either the postbiotic or a dummy pill (placebo) for two menstrual cycles. They'll keep track of their period and training, complete questionnaires about their gut symptoms, and provide stool samples to check gut health. The goal is to understand if this supplement can improve comfort and performance by easing gut problems in female athletes.

At a glance

Status

Recruiting

Phase

Sponsor

Liverpool John Moores University

Enrolment target

100

Start

05 May 2026

Estimated completion

30 May 2027

Gastrointestinal Symptoms Menstrual Cycle

What is this study about?

Many active women experience uncomfortable tummy and gut problems, particularly during exercise or at certain times in their menstrual cycle. These symptoms can make training difficult and affect how well they perform. However, there isn't much research on how to help relieve these issues for physically active women.

This study is looking into a product called a postbiotic. Postbiotics are non-living parts of helpful microbes that might support gut health. They could do this by strengthening the gut lining and influencing the good bacteria already in your gut. While similar products have shown promise in other groups, we don't fully understand if they can help physically active women, especially considering how their symptoms might change throughout their menstrual cycle.

So, this study aims to find out if taking a postbiotic supplement every day can reduce these gut symptoms in active women. Researchers will compare the postbiotic to a 'placebo' – a pill that looks the same but doesn't contain any active ingredient. This helps them see if any improvements are truly due to the postbiotic or just the idea of taking something.

Key takeaways

Targets active women with gut issues during exercise and menstruation.
Compares a postbiotic supplement to a dummy pill (placebo).
Involves tracking periods, training, and gut symptoms via questionnaires.
Stool samples will be collected to assess gut health.
Aims to improve comfort and performance in female athletes.
Participation lasts for two menstrual cycles.

Who may be eligible?

This study is looking for women who are at least 18 years old, are physically active, and have regular periods (not using hormonal birth control). You should also have experienced regular tummy or gut problems during exercise and around your period in the last month.

To be considered, you'll need to have a healthy body weight (BMI between 18.5 and 24.9) and be able to keep your usual diet and exercise habits the same throughout the study. You should also be able to give informed consent, meaning you understand what the study involves and agree to take part.

You won't be able to join if you are pregnant, breastfeeding, or planning to become pregnant. Also, if you've been on hormonal contraceptives in the last six months (or plan to use them during the study), if you're a smoker or vaper, or if you've had a recent injury or acute illness, you won't be eligible.

Could this study suit you?

Answer these quick questions to see if you may be eligible. This is a guide only — the research team makes the final call.

Are you a woman aged 18 or older with regular periods?
Do you get tummy or gut problems during exercise or around your period?
Are you physically active, training at least 3 times a week for an hour?
Are you able to maintain your usual lifestyle during the study?
Are you not pregnant, breastfeeding, or planning pregnancy soon?
Have you avoided hormonal contraception for the last 6 months?

Answer every question to see your result.

What does participation involve?

If you join this study, you will be asked to take either the postbiotic supplement or a dummy pill (placebo) once a day for two full menstrual cycles. You won't know which one you're taking. During this time, you'll need to track your menstrual cycle and your training routines. You'll also regularly fill out questionnaires about your gut symptoms, focusing on how you feel during your period and throughout your cycle. You will also provide stool samples so researchers can look at your gut health. The total duration of your active involvement in the study will depend on your menstrual cycle length, but it will cover two consecutive cycles.

Potential risks and benefits

Taking part in this study might help us understand more about managing gut symptoms in active women, which could potentially improve your comfort during training and competition. However, there's no guarantee that you will personally benefit from the supplement. As with any study, there could be unforeseen risks or side effects from taking the supplement, though postbiotics are generally considered safe. You are free to withdraw from the study at any time, for any reason, without it affecting your medical care.

Locations (1)

Some site locations are approximate. We're improving this — please verify with the trial team before travelling.

Tom Reilley Building
Verified postcode
Liverpool, United Kingdom· Recruiting

Common questions

What is a postbiotic?

A postbiotic is a product made by beneficial bacteria that is not alive. It is thought to support gut health.

What is a placebo?

A placebo is a 'dummy' pill that looks just like the real supplement but doesn't contain any active ingredients. It helps researchers see if the real supplement actually works.

Will I know if I'm taking the real supplement or the placebo?

No, this is a 'blinded' study, meaning neither you nor the research team will know which pill you are taking until after the study is complete. This helps keep the results fair.

How long will I need to be in the study?

You will participate for two full menstrual cycles, which will vary slightly depending on the length of your own cycle. This typically means a few months.

What happens to the information I provide?

All your personal information will be kept confidential. The data collected will help researchers understand the effects of the postbiotic supplement.

How to find out more

Kelsie Johnson, PhD

k.o.johnson@ljmu.ac.uk +44 0151 231 2121 Official trial record

Always speak to your GP or specialist before deciding to take part in a study.