We all eat microbes: diet as reservoir of microorganisms that preserve the ecosystem services of the human gastrointestinal microbiota (the μbEat project)
| ISRCTN | ISRCTN12131144 |
|---|---|
| DOI | https://doi.org/10.1186/ISRCTN12131144 |
| Sponsor | University of Milano-Bicocca |
| Funder | Ministero dell'Università e della Ricerca |
- Submission date
- 22/12/2025
- Registration date
- 26/01/2026
- Last edited
- 26/01/2026
- Recruitment status
- No longer recruiting
- Overall study status
- Ongoing
- Condition category
- Digestive System
Plain English summary of protocol
Background and study aims
Modern diets often contain fewer live microorganisms because of food processing and hygiene practices. This may reduce exposure to microbes that could play a role in supporting gut health, immune function, and metabolic balance. The aim of this study is to evaluate whether consuming a diet rich in naturally occurring food-associated microorganisms, compared with a diet low in microorganisms, affects the gut microbiome, blood metabolites, immune markers, and metabolic status in healthy adults.
Who can participate?
Healthy adult volunteers aged between 18 and 60 years can participate. Individuals with gastrointestinal diseases, recent infections, recent antibiotic use, pregnancy or breastfeeding, or other conditions that could interfere with the study are excluded.
What does the study involve?
This is a randomized, controlled, open-label crossover dietary intervention. Participants will follow two different diets:
• a diet low in microorganisms, and
• a diet rich in naturally occurring food-associated microorganisms.
Each diet will be followed for 8 weeks, separated by an 8-week washout period, with the order randomized. During the study, participants will provide stool, blood, and saliva samples and will complete food diaries and questionnaires to monitor diet and bowel habits.
What are the possible benefits and risks of participating?
Participants may gain insight into their own dietary habits and gut microbiome profile. There is no direct guaranteed health benefit. Risks are minimal and mainly related to blood sampling (e.g. mild discomfort or bruising) and the effort required to follow specific dietary instructions.
Where is the study run from?
The study is coordinated by the University of Milano-Bicocca. Sample collection is carried out in collaboration with the Fondazione IRCCS San Gerardo dei Tintori (Monza), and laboratory analyses are performed at University of Milano-Bicocca facilities and collaborating academic laboratories.
When is the study starting and how long is it expected to run for?
The study is expected to start in mid-2024 and will run for approximately 18 months, including recruitment, intervention periods, and sample analyses.
Who is funding the study?
The study is funded by the Italian Ministry of University and Research through the PRIN 2022 project (code 2022TF9AHZ_001).
Who is the main contact?
The main contact and principal investigator is Prof. Simone Guglielmetti, University of Milano-Bicocca, simone.guglielmetti@unimib.it
Contact information
Principal investigator, Scientific, Public
Piazza della Scienza 4
Milan
20126
Italy
 ORCID ID |
0000-0002-8673-8190 |
|---|---|
| Phone | 0264483343 |
| simone.guglielmetti@unimib.it |
Study information
| Primary study design | Interventional | |
|---|---|---|
| Allocation | Randomized controlled trial | |
| Masking | Open (masking not used) | |
| Control | Active | |
| Assignment | Crossover | |
| Purpose | Prevention | |
| Scientific title | Evaluation of the effect of diet-associated microorganisms on the gut microbiome, blood metabolome, immune system, and metabolic status in healthy adult subjects: a randomized controlled crossover dietary intervention (μbEat-trial) | |
| Study acronym | μbEat | |
| Study objectives | To assess whether the ingestion of naturally occurring food-associated microorganisms modulates gut microbiome biodiversity and is associated with changes in immune and metabolic markers in healthy adults. | |
| Ethics approval(s) |
Approved 07/05/2024, Comitato Etico dell’Università degli Studi di Milano-Bicocca (Piazza dell’Ateneo Nuovo, 1, Milano, 20126, Italy; +39 02 6448 6581; comitatoetico@unimib.it), ref: Protocollo n. 835 | |
| Health condition(s) or problem(s) studied | Prevention of low-grade chronic systemic inflammation and related non-communicable disease risk through modulation of the gut microbiome, immune function, and metabolic status in healthy adult subjects. | |
| Intervention | Two dietary interventions: 1. Low microbial diet (LM): diet designed to minimize ingestion of live food-associated microorganisms. 2. Microbe-enriched diet (MR): diet allowing and promoting ingestion of foods naturally rich in live microorganisms. Each intervention lasts 8 weeks, separated by an 8-week washout period, according to a randomized crossover design. Treatment sequences were generated using computer-based randomization in Microsoft Excel (RAND function), with balanced allocation to the predefined cross-over sequences. | |
| Intervention type | Other | |
| Primary outcome measure(s) |
| |
| Key secondary outcome measure(s) |
| |
| Completion date | 28/02/2026 |
Eligibility
| Participant type(s) | |
|---|---|
| Age group | Adult |
| Lower age limit | 18 Years |
| Upper age limit | 60 Years |
| Sex | All |
| Target sample size at registration | 59 |
| Key inclusion criteria | 1. Healthy adult subjects, without diagnosed acute or chronic diseases 2. Age between 18 and 60 years 3. Ability to provide written informed consent 4. Willingness and ability to comply with the dietary intervention, sample collection (feces, blood, saliva), and study procedures. |
| Key exclusion criteria | 1. Use of antibiotics within 1 month prior to study start 2. Use of antacids or gastrointestinal prokinetic drugs 3. Chronic inflammatory bowel diseases 4. Active irritable bowel syndrome (IBS) 5. Viral or bacterial enteritis within 2 months prior to enrollment 6. History of gastric or duodenal ulcers within the previous 5 years 7. Any severe disease that could interfere with the dietary intervention or study outcomes 8. Pregnancy or breastfeeding 9. Recent history or suspicion of alcohol or drug abuse 10. Poor reliability or conditions affecting compliance/adherence to the study protocol 11. Previous participation in this study |
| Date of first enrolment | 09/09/2024 |
| Date of final enrolment | 09/01/2026 |
Locations
Countries of recruitment
- Italy
Study participating centres
Results and Publications
| Individual participant data (IPD) Intention to share | No |
|---|---|
| IPD sharing plan summary | Not expected to be made available |
| IPD sharing plan |
Editorial Notes
22/12/2025: Trial's existence confirmed by Comitato Etico dell’Università degli Studi di Milano-Bicocca.
