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Can prebiotic supplementation increase carbohydrate use during exercise? Join our study

We need cyclists and/or triathletes to take part in a 12-week research study assessing prebiotic supplementation's impact on carbohydrate use during exercise.

The purpose of this study is to understand if supplementation with the prebiotic Galactooligosaccharide can increase people’s use of ingested carbohydrate during exercise. We also hope to increase our understanding of how prebiotics affect the availability of other nutrients, such as vitamins and minerals.

We are currently recruiting for this study until 25 October 2025.

Research background

Current evidence suggests that the amount of ingested carbohydrate that we can use for energy during exercise is limited by absorption capacity in the gut.

Strategies to increase the amount of this carbohydrate we can use are of great interest, because of its link to improved performance.

Recent research has shown we may be able to use more of the ingested carbohydrate during exercise when supplementing with probiotics ("good bacteria" for our gut). It is currently unknown whether the food for these "good bacteria” (known as prebiotics) can induce a similar effect.

What you’ll do

After an initial eligibility screening, you’ll undertake preliminary testing and familiarisation. This will take place on our University of Bath campus and last around 2.5 hours.

The remaining visits (four exercise trials and two baseline sample collections) will be split across three main blocks, each lasting 28 days.

After preliminary testing, you’ll be randomised into supplementing with either the prebiotic (BIMUNO®) or a placebo.

Block 1 will begin with a laboratory visit for a baseline sample collection, after which you’ll begin 28 days of supplementation.

After this 28-day period, you’ll complete two exercise trials. The ambient temperature in these trials will differ (20˚C and 35˚C) and be separated by more than three days.

Block 2 (the ‘washout’ period) will be 28 days where you will take neither BIMUNO® nor the placebo.

Block 3 will be identical to block 1 – the only difference being you consume the other supplement.

A cyclist stood by their bike looking out over a view of some hills.

What you’ll get for taking part

By completing this study, you will help us to advance our research in this important area.

You will also receive a personalised summary of your own results, including:

  • Lactate threshold
  • Maximal aerobic capacity (VO2max)
  • Body composition analysis via DEXA scan
  • Blood test results
  • Carbohydrate oxidation rate, which can be used to provide you with an individualised nutrition plan for training/competition
A person using breathing apparatus while on an exercise bike.

Take part in this research

Find out more about taking part in this research study.


To participate in this study, you should be:

  • A regular exerciser (participate in at least 30 minutes of structured exercise at least three times per week)
  • Able to complete two hours of moderate-intensity cycling
  • Aged between 18 and 60

You will not be able to take part in this study if you:

  • Have used products marketed as prebiotics, probiotics or synbiotics within four weeks of starting the study. These include Yakult, Actimel, Activia, VSL#3, Kefir and some others. Please note: consuming regular cheese or yogurt containing lactic acid bacteria is not cause for exclusion
  • Have undergone systemic antibiotic or antimycotic treatment within four weeks of starting the study
  • Are following diets likely to affect the study's outcome. These include:
    • Low FODMAP
    • KETO/high-fat
    • Gluten free/coeliac
    • Paleo
    • Weight loss (caloric restriction, low-carbohydrate)
    • 5:2/whole day energy restriction
    • Atkins/high-protein
    • Sugar-free
    • Single-food
    • Juicing/any day of juicing
    • Any other restricted diet (such as very low calory)
    • Vegan diets (Galactooligosaccharide is derived from cow’s milk).

You should let the lead researcher know about any changes in your diet, supplement use or medication that may affect study outcomes within two months prior to study entry or planned during the study.

Your data

All records will be treated as confidential, including personal contact details.

Data collection and retention will comply fully with General Data Protection Regulation (GDPR) and will only be accessible to the lead researcher and their supervisor.

Contact Adam Collins (lead researcher) to sign up for this study

Email Adam Collins (