Investigating the role of dietary probiotics on athletic performance and health
| ISRCTN | ISRCTN15642871 |
|---|---|
| DOI | https://doi.org/10.1186/ISRCTN15642871 |
| Sponsor | Nottingham Trent University |
| Funders | Biotechnology and Biological Sciences Research Council, International Flavors & Fragrances Inc. |
- Submission date
- 20/05/2026
- Registration date
- 29/06/2026
- Last edited
- 11/06/2026
- Recruitment status
- No longer recruiting
- Overall study status
- Ongoing
- Condition category
- Nutritional, Metabolic, Endocrine
Plain English summary of protocol
Background and study aims
Athletes often train hard with limited time to recover. Recent research shows that exercise can change the gut microbiome, the community of bacteria living in the gut, and this may influence performance and recovery. During intense exercise, the body produces lactate, which can build up and cause fatigue. Some gut bacteria can convert lactate into helpful substances called short‑chain fatty acids (SCFAs), which may support energy use, recovery, and overall health. Early studies suggest that certain probiotics (beneficial live bacteria) might help this process and could even improve exercise performance, but there is very little evidence in active people.
This study aims to find out whether taking a daily probiotic for two weeks can help the body manage lactate during exercise, improve performance, and support gut and immune health. The study will test two probiotic strains developed by International Flavors & Fragrances Inc. to see whether they can benefit physically active men.
Who can participate?
Physically active male volunteers aged 20–40 years who train at least 4 times per week and can run a 5 km time trial in under 21 minutes (within the last 3 months).
What does the study involve?
Preliminary visit :
-Speed lactate test (submaximal exercise test consisting of 3 min stages incrementally increasing in speed; capillary tube of blood taken in between)
-Self-paced 5km treadmill time trial
Experimental visits (4 visits total) :
Pre-supplement and on day 14 of the supplement period:
- Collection of a stool sample before arrival at the laboratory
- Questionnaires on sleep, wellness, gastrointestinal symptoms and illness.
- Speed lactate test
- Self‑paced 5 km treadmill time trial
- Blood and saliva samples before, during, and after the exercise tests
Supplementation:
Participants will be given either a probiotic supplement or a taste‑matched placebo by chance. They will take 1 capsule per day for 12 days, then 5 capsules per day on days 13 and 14. Participants will take each supplement separately during 14-day periods separated by a period without any supplement, known as a wash-out (minimum of 2-weeks). Neither the researchers nor the participants will know the order of each 14-day supplement period. Weekly and daily questionnaires will also be completed during the supplementation periods.
What are the possible benefits and risks of participating?
Possible benefits:
-Insight into fitness, performance, microbiome and response to a probiotic supplement.
-Contribute to new research on probiotics, gut health, and exercise performance.
-Helping shape future nutrition and sports science research.
Possible risks:
-Some discomfort may be experienced during venepuncture for the blood sample. However, the venepuncture procedure has been risk-assessed and, in relation to current experience at NTU, is safe. Staff who perform the procedure are appropriately trained, and sterile procedures are used at all times.
-Although rare, the supplement may cause dose-dependent gastrointestinal side effects such as bloating.
-Although it is extremely unlikely, high-intensity exercise has been known to reveal unsuspected heart or circulation problems, and very rarely these have had serious or fatal consequences.
-Nausea, dizziness, and light-headedness can be experienced during and following maximal exercise.
Where is the study run from?
The study is being conducted at Nottingham Trent University, within the Sport Health and Performance Enhancement (SHAPE) Research Centre.
When is the study starting and how long is it expected to run for?
The study will run over several months, with each participant involved for approximately six to eight weeks, including the supplementation period and testing visits.
Who is funding the study?
1. The Biotechnology and Biological Sciences Research Council (BBSRC) INFORM Hub
2. Industry partner IFF (International Flavors & Fragrances Inc.)
Who is the main contact?
Dr Neil Williams, neil.williams@ntu.ac.uk
Contact information
Principal investigator, Public, Scientific
Nottingham Trent University, Burton Street
Nottingham
NG1 4BU
United Kingdom
 ORCID ID |
0000-0002-2607-4572 |
|---|---|
| Phone | +44 (0)115 848 5535 |
| Neil.Williams@ntu.ac.uk |
Study information
| Primary study design | Interventional |
|---|---|
| Allocation | Randomized controlled trial |
| Masking | Blinded (masking used) |
| Control | Placebo |
| Assignment | Crossover |
| Purpose | Basic science |
| Scientific title | Investigating the role of dietary probiotics on athletic performance and health via lactate and SCFA metabolism |
| Study acronym | PROPIONI Study |
| Study objectives | The objective of this project is to establish the efficacy of a dual strain probiotic from the genus's of Propionibacterium and Lacticaseibacillus on lactate and propionate metabolism during exercise, exercise performance, recovery, the gut microbiome, and biomarkers of gut damage, and immunity. |
| Ethics approval(s) |
Approved 30/03/2026, Nottingham Trent University’s Human Invasive Ethics Committee (Nottingham Trent University, Burton Street, Nottingham, NG1 4BU, United Kingdom; +44 (0)115 848 3461; dianne.levey@ntu.ac.uk), ref: 2538032 |
| Health condition(s) or problem(s) studied | Exercise performance and metabolism |
| Intervention | The study will be a 2-month double-blind, randomised, placebo-controlled crossover intervention trial in endurance-trained males. All participants will complete the treatment (probiotic supplement) and control (placebo supplement) conditions of the study, the order of which will be randomly assigned using simple randomisation at the site of manufacture by the industry partner. Both the probiotic and placebo will be taken for 14 days in capsule form. A minimum of 2 weeks' wash-out will be completed between conditions. Supplementation of probiotics: 3B Propionibacterium; 1 B Lactobacillus rhamnosus LC-705 for the first 12 days of the 14-day supplementation period (in 1 capsule/day), and 15B Propionibacterium; 5B Lactobacillus rhamnosus LC-705 for the last 2 days of the 14-day supplementation period (in 5 capsules/day). Supplementation of placebo (taste and appearance matched): Capsule containing maltodextrin powder (1 capsule per day for days 1-12, followed by 5 capsules per day for days 13 and 14). Pre and post supplementation periods, participants will visit the laboratory where they will complete a submaximal exercise test (speed lactate test) and an exercise performance trial (self-paced 5km time trial), both on a motorised treadmill. During the exercise tests, lactate concentration, heart rate, rating of perceived effort (RPE), and gastrointestinal (GI) symptoms will be recorded. The submaximal exercise test will proceed until the Onset of Blood Lactate Accumulation (OBLA; blood lactate concentration of 4mmol/L). At rest (pre), following the submaximal exercise test (during), and following the exercise performance trial (post), saliva (salivary IgA, cortisol) and venous blood samples (venous propionate, intestinal-fatty acid binding protein [I-FABP], lipopolysaccharide binding protein [LBP], testosterone) will be taken. Participants will also provide a stool sample pre and post supplementation period for the assessment of gut microbiome composition via DNA extraction and shotgun metagenomics, and will complete questionnaires related to illness (daily), sleep and wellness (weekly), and longitudinal GI symptoms (weekly). |
| Intervention type | Supplement |
| Primary outcome measure(s) |
|
| Key secondary outcome measure(s) |
|
| Completion date | 30/11/2026 |
Eligibility
| Participant type(s) | |
|---|---|
| Age group | Adult |
| Lower age limit | 20 Years |
| Upper age limit | 40 Years |
| Sex | Male |
| Target sample size at registration | 20 |
| Key inclusion criteria | 1. Male 2. Aged between 20-40 years 3. Physically active and defined as “trained” in line with McKay et al. (2022) 4. Have a 5km time trial personal best of <21 minutes within the last three months |
| Key exclusion criteria | 1. Routine consumption of ω-3 PUFA supplements and/or supplements with antioxidants 2. Routine consumption of prebiotic, and/or probiotic supplements 3. Routine consumption of collagen-based supplements 4. Use of antibiotics in the past 3 months 5. Milk allergy or lactose intolerance 6. Take a daily dose of aspirin or other NSAIDs 7. Intake of drugs which affect gastrointestinal mobility/laxatives in the 4 weeks before the study 8. Previously diagnosed with COPD, emphysema, chronic bronchitis or similar respiratory illness 9. History of heart failure, pulmonary hypertension, embolism, or other pulmonary heart disease 10. History of recurrent chest infections 11. Smoker 12. Acute infection within the last four weeks 13. Major operation within the past four months 14. History of gastrointestinal drug reaction 15. History or current evidence of gastrointestinal disease, e.g. chronic constipation, diarrhoea, irritable bowel syndrome, Crohn’s Disease |
| Date of first enrolment | 14/05/2026 |
| Date of final enrolment | 19/10/2026 |
Locations
Countries of recruitment
- United Kingdom
- England
Study participating centre
Nottingham
NG1 4BU
England
Results and Publications
| Individual participant data (IPD) Intention to share | No |
|---|
Editorial Notes
11/06/2026: Study’s existence confirmed by the Nottingham Trent University Human Invasive Ethics Committee, UK.
