The effects of dairy-based protein supplementation on immunity following exercise
| ISRCTN | ISRCTN56356024 |
|---|---|
| DOI | https://doi.org/10.1186/ISRCTN56356024 |
| Secondary identifying numbers | UoK SSES REAG Ref No. 26_20_23 |
- Submission date
- 11/05/2023
- Registration date
- 16/05/2023
- Last edited
- 12/05/2025
- Recruitment status
- No longer recruiting
- Overall study status
- Ongoing
- Condition category
- Other
Plain English summary of protocol
Background and study aims
Upper respiratory tract infections (URTI) are among the most common illnesses in athletes. Whilst moderate amounts of exercise are accepted to enhance immune function and reduce URTI risk, strenuous prolonged exercise has been shown to increase the chances of picking up some types of infection among athletes. URTIs may affect performance both directly (if suffered during/near competition) or indirectly (impeding training). Therefore, methods to alleviate and lower this risk are of interest. Treatments such as elevated protein diets and milk-based products such as bovine colostrum have been shown to enhance immunity and reduce URTI incidence and/or severity in athletes. Therefore, the present study will investigate the effects of dairy-based protein supplementation on immune function and URTI symptoms/incidence in athletes following prolonged exercise.
Who can participate?:
Healthy volunteers over the age of 18 years who are free from any injury, illness or disease (cardiovascular, metabolic etc). Participants must also be free from any respiratory conditions, such as asthma or exercise-induced bronchoconstriction, and must be deemed ‘healthy’ via a pre-screening health questionnaire, with no allergies or intolerances to dairy or soy. Participants must be experienced with long-duration cycling, being able to complete a 3-hour cycling bout on three consecutive days.
What does the study involve?
Participants will visit the laboratory on ten separate occasions: two visits for ‘preliminary measures’ (VO2max test), two familiarisation visits and six experimental trials. Participants will be randomly assigned to one of two groups, either placebo (PLA) supplementation or whey protein concentrate (WPC) supplementation. Supplements will be taken for 14 days before the experimental trials begin and continued throughout the duration of the experimental trials. For each participant, there will be a 14-day washout period before completing the second crossover arm with the other supplement. The preliminary measures visits will consist of a VO2max test. The familiarisation and experimental trials will consist of a 3-hour cycling bout at a moderate intensity. Blood samples will be taken from a vein near the elbow crease. These samples will be taken once at preliminary measures trials and multiple times (i.e. before and after exercise) on experimental trials 1, 3, 4 and 6. Saliva samples will be collected on both preliminary measures trials and all experimental trials. For those unable to commit to the entire 3-day repeated main trial protocol, an alternative protocol with only a single main trial per study arm will be offered.
What are the possible benefits and risks of participating?
Participants will receive information on their fitness levels (i.e. VO2max test), which is usually a service that athletes might pay for. They will be provided with reasonable expenses so that they are not left out of pocket by taking part.
The 3-hour cycling bout may cause some delayed onset of muscle soreness. Blood samples may cause minor pain and distress for some participants and there is a minor risk of infection. The likelihood of adverse reactions or side effects to the use of the product is low in those who are not allergic to any of the ingredients. All exercise and physical activity has a risk of cardiac emergency or injury; for those without underlying heart disease, the risks to health are extremely low. Pre-screening will be used to exclude anybody for whom risk may be elevated above normal. Persons trained in CPR and with access to a defibrillator device will be on hand during all testing.
Where is the study run from?
The University of Kent (UK)
When is the study starting and how long is it expected to run for?
October 2022 to September 2025
Who is funding the study?
1. University of Kent (UK)
2. Volac International Ltd (UK)
Who is the main contact?
Will Searle, ws215@kent.ac.uk
Contact information
Public
University of Kent
Chipperfield Building
Park Wood Road
Canterbury
CT2 7PE
United Kingdom
 ORCID ID |
0000-0002-5132-2312 |
|---|---|
| Phone | +44 (0)7714735525 |
| ws215@kent.ac.uk |
Study information
| Study design | Single-centre double-blind placebo-controlled randomized crossover study |
|---|---|
| Primary study design | Interventional |
| Secondary study design | Randomised cross over trial |
| Study setting(s) | University/medical school/dental school |
| Study type | Other |
| Participant information sheet | Not available in web format, please use contact details to request a participant information sheet |
| Scientific title | The effects of dairy-based protein supplementation on immune function and infection risk following exercise |
| Study objectives | 1. Dairy-based protein supplementation will enhance immune function in athletes 2. Dairy-based protein supplementation will reduce upper respiratory tract infection (URTI) incidence following exercise |
| Ethics approval(s) | Approved 05/05/2023, University of Kent SSES Research Ethics and Advisory Group (University Of Kent, Chipperfield Building, Park Wood Road, Canterbury, CT2 7PE, UK; +44 (0)1227 816940; s.a.smith-75@kent.ac.uk), ref: Prop 26_20_22 |
| Health condition(s) or problem(s) studied | Maintenance or enhancement of immune function following exercise in healthy adults |
| Intervention | Randomisation will be performed with computerised randomisation software. Treatment will be administered double-blind with allocation concealment managed by a third-party staff member not involved with the study. In a double-blind, randomised order, participants will consume a whey protein concentrate (WPC; 40 g/day) or a placebo (40 g/day soy protein), replicating the macronutrient profile of the WPC. During the first crossover arm, participants will consume their designated supplement daily for 14 days and continue throughout the experimental trials, totalling 17 days. Participants will undergo a 2-week washout period between crossover arms, not consuming anything. Following the washout period, the second crossover arm will replicate the procedures used in the first arm, using the opposing supplement. |
| Intervention type | Supplement |
| Primary outcome measure | 1. Immune cell function will be measured in immune cells in/from whole blood samples by emitted light analysis at rest on preliminary trial days, and pre-, immediately post- and 1 h post-exercise on main trial days 1 and 3 of each study arm 2. Measures of mucosal immunity (secretory IgA and antimicrobial peptides/proteins) will be determined by ELISA assays in saliva at rest on preliminary trial days, and pre-, immediately post- and 1 h post-exercise on main trial days 1, 2 and 3 of each study arm |
| Secondary outcome measures | Current secondary outcome measures as of 25/02/2025: 1. Gut cell damage will be assessed by plasma iFABP levels by ELISA from blood samples obtained pre-, immediately post- and 1 h post-exercise on main trial days 1 and 3 of each study arm 2. Stress hormone will be measured by ELISA in blood samples obtained pre-, immediately post- and 1 h post-exercise on main trial days 1 and 3 of each study arm 3. Dairy lipid levels will be assessed by colorimetric coupled enzyme assay and/or NMR spectroscopy in blood samples obtained at rest (i.e. pre-exercise) on preliminary trial days and on main trial day 1 of each study arm 4. URTI incidence/symptoms will be measured using a daily self-report illness questionnaire (Jackson Common Cold Questionnaire) over the duration of the study 5. If participants believe they are ill, they will be asked to collect throat and nasal swab samples. These samples will be screened for the presence of known URTI-causing pathogens by qPCR. 6. In all experimental trials, participants will complete the state aspect of the State-Trait Anxiety Inventory (STAI-S) and Perceived Stress Scale prior to exercise 7. Participants will complete the Cohen-Hoberman Inventory of Physical Symptoms on experimental trials 1 and 4. 8. Bacterial load will be measured via qPCR on blood samples taken pre-exercise, post-exercise and 1-hour post-exercise on experimental trials 1, 3, 4 and 6. Previous secondary outcome measures: 1. Gut cell damage will be assessed by plasma iFABP levels by ELISA from blood samples obtained pre-, immediately post- and 1 h post-exercise on main trial days 1 and 3 of each study arm 2. Stress hormone and cytokine levels will be measured by ELISA in blood samples obtained pre-, immediately post- and 1 h post-exercise on main trial days 1 and 3 of each study arm 3. Dairy lipid levels will be assessed by colorimetric coupled enzyme assay in blood samples obtained at rest (i.e. pre-exercise) on preliminary trial days and on main trial days 1 and 3 of each study arm 4. URTI incidence/symptoms will be measured using a daily self-report illness questionnaire (Jackson Common Cold Questionnaire) over the duration of the study 5. If participants believe they are ill, they will be asked to collect throat and nasal swab samples. These samples will be screened for the presence of known URTI-causing pathogens by qPCR. 6. In all experimental trials, participants will complete the state aspect of the State-Trait Anxiety Inventory (STAI-S) and Perceived Stress Scale prior to exercise 7. Participants will be tested for Epstein-Barr Virus (EBV) serostatus by screening for the presence of the EBV viral capsid antigen IgG (by ELISA) in serum. This will be done on one resting sample from the beginning of each study arm. EBV DNA levels will be determined in all saliva samples by qPCR. Added 04/12/2023: 8. Participants will complete the Cohen-Hoberman Inventory of Physical Symptoms on experimental trials 1 and 4. Added 04/04/2024: 9. Bacterial load will be measured via qPCR on blood samples taken pre-exercise, post-exercise and 1-hour post-exercise on experimental trials 1, 3, 4 and 6. |
| Overall study start date | 01/10/2022 |
| Completion date | 30/09/2025 |
Eligibility
| Participant type(s) | Healthy volunteer |
|---|---|
| Age group | Adult |
| Lower age limit | 18 Years |
| Sex | Both |
| Target number of participants | n = 12. No previous data exists using the current supplement, so a preliminary power calculation conservatively using an effect size half that observed for a similar supplement determined that a sample size of 10 would provide 80% power (alpha level, 0.05) to detect differences between conditions. To protect against potential dropouts, we will aim to recruit 12 participants. |
| Total final enrolment | 11 |
| Key inclusion criteria | 1. Over 18 years old 2. Free from any injury, illness (no illness within 2 weeks) or disease 3. Free from any respiratory conditions (e.g. asthma) 4. Deemed healthy via a pre-screening health questionnaire 5. Experienced with long-duration cycling 6. Have no allergies or intolerances to dairy or soy |
| Key exclusion criteria | 1. Under 18 years old 2. Current injuries, illnesses or diseases 3. Asthmatics 4. Not deemed 'healthy' via a pre-screening health questionnaire 5. Inexperienced with long-duration cycling 6. Allergic or intolerant to dairy or soy |
| Date of first enrolment | 24/05/2023 |
| Date of final enrolment | 01/05/2025 |
Locations
Countries of recruitment
- England
- United Kingdom
Study participating centre
Park Wood Road
Canterbury
CT2 7PE
United Kingdom
Sponsor information
University/education
University of Kent
Canterbury
CT2 7NZ
England
United Kingdom
| Phone | +44 (0)1227 764000 |
|---|---|
| researchculture@kent.ac.uk | |
| Website | http://www.kent.ac.uk/ |
"ROR" |
https://ror.org/00xkeyj56 |
Funders
Funder type
Industry
No information available
Private sector organisation / Universities (academic only)
- Alternative name(s)
- The University of Kent
- Location
- United Kingdom
Results and Publications
| Intention to publish date | 24/05/2025 |
|---|---|
| Individual participant data (IPD) Intention to share | Yes |
| IPD sharing plan summary | Available on request |
| Publication and dissemination plan | Planned publication in a peer-reviewed journal |
| IPD sharing plan | The data generated during this study will be available upon request from Will Searle (ws215@kent.ac.uk) or Glen Davison (G.Davison@kent.ac.uk) after completion and publication of study results (de-identified participant data), and may be used for secondary analysis or as part of meta-analyses and other relevant and legitimate scientific uses only. All data will be fully anonymised so that it will not be possible for the identity of participants to be known or deduced. The researchers will ask those requesting data sharing to provide a brief research proposal on how they wish to use the data. This will then form the basis of a data-sharing agreement (if necessary/appropriate to do so), which will clearly detail the criteria for data access and conditions for research use. The researchers will also include a requirement for due acknowledgement and/or co-authorship (if/when appropriate) and acknowledgement of the funder for supporting the original study. |
Editorial Notes
12/05/2025: The total final enrolment was added.
26/02/2025: The target number of participants was edited to add "No previous data exists using the current supplement, so a preliminary power calculation conservatively using an effect size half that observed for a similar supplement determined that a sample size of 10 would provide 80% power (alpha level, 0.05) to detect differences between conditions. To protect against potential dropouts, we will aim to recruit 12 participants".
25/02/2025: The following changes were made to the study record:
1. The target number of participants was changed from 16 to 12.
2. Secondary outcome measures updated.
3. The recruitment end date was changed from 01/03/2025 to 01/05/2025.
4. The overall study end date was changed from 24/05/2025 to 30/09/2025.
04/04/2024: The following changes were made to the trial record:
1. The recruitment end date was changed from 01/03/2024 to 01/03/2025.
2. The overall end date was changed from 24/05/2024 to 24/05/2025.
3. The plain English summary was updated to reflect these changes.
4. The secondary outcome measures were updated.
04/12/2023: The secondary outcome measures were changed.
20/11/2023: The sponsor contact email has been changed.
15/05/2023: Study's existence confirmed by the University of Kent SSES Research Ethics and Advisory Group.
