Condition category
Not Applicable
Date applied
Date assigned
Last edited
Prospectively registered
Overall trial status
Recruitment status

Plain English Summary

Background and study aims
The gut microbiome is the totality of microorganisms, bacteria, viruses, protozoa, and fungi, and their collective genetic material present in the gastrointestinal tract.
Vegan diets have been widely adopted in the athletic population in recent years. However, the influence of vegan diets on exercise performance and energy processing (metabolism) is still controversial.
The study aims to determine gut microbiome adaptation to extreme endurance exercise according to vegan or omnivore diet consumed in ultra-marathoners. We also seek to evaluate long-term vegan and omnivore diets' effects on exercise capacity, oxidant/antioxidant capacity, muscle fatigue, and assess energy availability

Who can participate?
Ultra-marathoners with age between 18 to 49 years who are competing in the Sri-Chinmoy ultra-marathon race

What does the study involve?
Our study will run for one year. During this period, research data will be collected from the participants in four steps (three visits to the research laboratory and the race day) throughout the study. Study participants will be asked to visit the study laboratory for three times (first and second visits before the race and the third visit 24 hours after the race).

What are the possible benefits and risks of participating?
Participants will receive reliable information about their nutrition and performance status from health professionals.
There are no additional risks.

Where is the study run from?
1. University Hospital of Zurich (Switzerland)
2. Sri-Chinmoy race (St. Jakob sports complex) (Switzerland)

When is the study starting and how long is it expected to run for?
January 2020 to May 2021

Who is funding the study?
University Hospital of Zurich (Switzerland)

Who is the main contact?
Prof Beat Knechtle,
Dr Asli Devrim Lanpir,

Trial website

Contact information



Primary contact

Prof Beat Knechtle


Contact details

Säntisstrasse 8
Freidorf TG



Additional contact

Dr Asli Devrim Lanpir


Contact details

22 Istiklalim Street
+90-(0)-216-280-33-33/ 4150

Additional identifiers

EudraCT number

Nil known number

Nil known

Protocol/serial number


Study information

Scientific title

Vegan vs. omnivore diets paradox: Determining the effects of dietary pattern on exercise-induced symptoms and a whole-metagenomic approach towards defining metabolic networks during the race in ultra-marathoners


Study hypothesis

1. According to gut metagenomics, vegan ultra-marathoners have higher alpha and beta diversity than omnivorous ultra-marathoners
2. Vegan ultra-marathoners have lower energy availability, macro- and micronutrient intakes than omnivore ultra-marathoners
2. Ultra-marathoners following a long-term vegan diet have a higher antioxidant capacity, lower oxidant capacity, and muscle fatigue than omnivorous ultra-marathoners
3. There is no difference between vegan and omnivorous ultra-endurance athletes in terms of gut microbiome adaptation to ultra-marathon races

Ethics approval

Approved 24/06/2020, Istanbul Medeniyet University Göztepe Training and Research Hospital Clinical Research Ethics Committee (Doktor Erkin Street, Kadıköy / Istanbul, Turkey; +90216570 9190;, ref: 2020/0396

Study design

Before and after study design

Primary study design


Secondary study design

Before and after study design

Trial setting


Trial type


Patient information sheet

Not available in web format, please use the contact details to request a patient information sheet.


Ultra-marathoners adhering to a vegan or omnivorous diet at least 6 months


Participants will be classified as either vegan (no type of animal product consumption - dietary adherence <6 months) or omnivorous (consumption of any animal products - dietary adherence <6 months) based on self-reporting of diet consumed.

Twenty four participants will be assigned to the study, including twelve vegan and twelve omnivorous ultra-marathoners competing in the Sri-Chinmoy ultra marathon race. Research data will be collected at the University of Zurich Research Laboratory between June 2021 and August 2021, and on the Sri-Chinmoy ultra-marathon race day in July 2021. Research data will be collected from the participants at four steps (three visits to the research laboratory and the race day) throughout the study. At the first visit, fecal samples, and anthropometric measurements will be collected. Body composition will be measured using DXA. Participants will be informed about keeping detailed food and liquid records and will be asked to record their diet data during the study period. Additionally, they will be asked to wear accelerometers during this period. At second visit, maximum oxygen consumption will be measured on a treadmill. At the race day, blood samples will be collected immediately before, and 0. min, two hours, and 24 hours before the race. The blood and fecal samples will be stored at -80 C until analysis. Plasma malondialdehyde, reactive oxygen metabolites (d-ROMs), total antioxidant capacity, and HSP70, and serum Orosomucoid 1 will be analyzed in blood samples. Fecal samples will be analyzed with shotgun metagenomic analysis and interpreted using the bioinformatics pipeline (HumanN2). Statistical tests will be analyzed using SPSS version 23.0 (IBM, Armonk, NY) and R Software (Dusseldorf, Germany). Laboratory analyses will be covered by the Institute of Primary Care, University Hospital Zurich.

Individual results of the VO2max values, nutritional assessment according to food and fluid records, energy availability, body mineral density, and microbiota structure will be discussed in detail with the participants. Further, they will receive individual consultations on obtaining adequate energy and nutrient intake. As a result of this study, participants will receive reliable information about their nutrition and performance status from health professionals.
The increase of heart rate during the incremental running test will be continuously monitored in order to prevent an adverse reaction, and only healthy participants with no history of cardiovascular disease will be invited to participate in the study. The Physical Activity Readiness Questionnaire (PAR-Q) will be applied to assess current cardiovascular health. Participants answering no to all questions will be considered as eligible for physical activity. The standard emergency equipment will be available in the research laboratory. Blood samples will be collected by a healthcare professional while the participants are positioned in a semi-reclined position to avoid risks associated with blood collection. Lactate measurements will be performed using sterile lancets to prevent risk of exposure to bloodborne pathogens.

Intervention type



Drug names

Primary outcome measure

Intestinal microbial adaptation according to applied diet evaluated by analysing faecal samples taken seven days before and seven days after the race using shotgun metagenomic analysis

Secondary outcome measures

Oxidative stress and muscle fatigue-related biomarkers measured using blood samples immediately before, at the end of 0 h, 2 h and 24 h of the race

Overall trial start date


Overall trial end date


Reason abandoned (if study stopped)


Participant inclusion criteria

1. Ultra-marathoners with age between 18 to 49 years
2. Competing in the Sri-Chinmoy ultra-marathon race
3. No use of probiotics and antibiotics in the preceding 3 months
4. No history of acute or chronic illnesses

Participant type

Healthy volunteer

Age group




Target number of participants


Participant exclusion criteria

Does not meet inclusion criteria

Recruitment start date


Recruitment end date



Countries of recruitment


Trial participating centre

University Hospital Zurich
Institute of Primary Care

Trial participating centre

Sri-Chinmoy race (St. Jakob sports complex)
Brüglingerstrasse 21

Sponsor information


University Hospital of Zurich

Sponsor details

Institute of Primary Care
+41 44 634 11 11

Sponsor type

Hospital/treatment centre



Funder type

Hospital/treatment centre

Funder name

Universitätsspital Zürich

Alternative name(s)

University Hospital Zurich, USZ

Funding Body Type

government organisation

Funding Body Subtype

Local government



Results and Publications

Publication and dissemination plan

Planned publication in a high-impact peer-reviewed journal.

IPD sharing statement:
All data generated or analysed during this study will be included in the subsequent results publication.

Intention to publish date


Participant level data


Basic results (scientific)

Publication list

Publication citations

Additional files

Editorial Notes

10/11/2020: Trial’s existence confirmed by Istanbul Medeniyet University Göztepe Training and Research Hospital Clinical Research Ethics Committee.