Mediterranean diet adherence, testicular function and fertility
| ISRCTN | ISRCTN48060037 |
|---|---|
| DOI | https://doi.org/10.1186/ISRCTN48060037 |
| Strategic Action in Health-Strategic Lines of Health Research, Carlos III Health Institute, Spain. | AES-LEIS 2024-2027 |
| Protocol serial number | PI25/00603 |
| Sponsor | Instituto de Salud Carlos III |
| Funder | Instituto de Salud Carlos III |
- Submission date
- 23/12/2025
- Registration date
- 30/12/2025
- Last edited
- 30/12/2025
- Recruitment status
- Not yet recruiting
- Overall study status
- Ongoing
- Condition category
- Nutritional, Metabolic, Endocrine
Plain English summary of protocol
Background and study aims
Mediterranean Diet (MedDiet) health benefits are well-documented and several randomly allocated clinical trials (RCT) and observational studies have proven that it is effective in reducing the risk of cardiovascular diseases, diabetes, and overall mortality but no clear associations/effects were observed on testicular function and fertility outcomes. The main objective of this study is to assess the associations/effects of a MedDiet on testicular function and fertility. The study hypothesizes that adherence to a MedDiet improves testicular function and reduces the risk of infertility.
This project will be the first to observationally and prospectively assess the role of a food pattern (MedDiet) in the primary prevention of infertility by assessing the diet-testicular function-fertility axis and the possible mechanisms implicated. Built on three well-conducted cohort studies and a newly designed RCT, the MEDFERTYL project will lead to translatable dietary interventions and contribute to the paradigm shift towards precision nutrition for fertility programs.
Who can participate?
Healthy male volunteers at reproductive age (18-40 years old).
What does the study involve?
The study will assess the associations between MedDiet adherence, testicular function, and fertility using international cohorts of individuals or couples. To assess the effect of the MedDiet on testicular function (seminogram and peripheral hormone level) and possible mechanisms implicated (sperm DNA integrity, sperm chromatin condensation, and sperm methylation).
What are the possible benefits and risks of participating?
Benefits: It is possible that you may not obtain any health benefits from participating in this study. The aim of the study is to deepen knowledge of male infertility in order to improve its detection, diagnosis, and treatment. In the short term, the results obtained in the study are not expected to directly benefit the participant, but rather to benefit the general population.
Risks: The study does not involve any risk beyond that associated with blood collection. Drawing the blood sample may cause a stinging sensation at the point where the needle is inserted into the skin and may result in a small bruise that disappears after a few days. More rarely, it may cause transient dizziness.
Where is the study run from?
Carlos III Health Institute, Spain.
When is the study starting and how long is it expected to run for?
January 2026 to December 2028.
Who is funding the study?
Strategic Action in Health-Strategic Lines of Health Research, Carlos III Health Institute, Spain.
Who is the main contact?
Dr. Albert Salas-Huetos, albert.salas@urv.cat
Contact information
Public, Scientific, Principal investigator
C/Sant Llorenç, 21
Reus
43201
Spain
 ORCID ID |
0000-0001-5914-6862 |
|---|---|
| Phone | +34 977759379 |
| albert.salas@urv.cat |
Study information
| Primary study design | Interventional | |
|---|---|---|
| Allocation | Randomized controlled trial | |
| Masking | Blinded (masking used) | |
| Control | Placebo | |
| Assignment | Parallel | |
| Purpose | Prevention | |
| Scientific title | Mediterranean diet adherence, testicular function and fertility | |
| Study acronym | MedFertyl | |
| Study objectives | Main: To assess the effects of a Mediterranean diet (MedDiet) on testicular function. 1. To assess the effect of a MedDiet, compared to the usual diet, on 1) semen parameters (primary endpoint), and 2) peripheral levels of reproductive hormones. 2. To assess the effect of a MedDiet, compared to the usual diet, on the main possible mechanism of the changes: 1) sperm DNA integrity, 2) sperm chromatin condensation, and 3) sperm methylation. | |
| Ethics approval(s) |
Approved 18/12/2025, Comité Ético de Investigación con Medicamentos IISPV (Hospital Universitario Sant Joan de Reus, Avda. Josep Laporte, 2, Reus, 43204, Spain; +34 977779946; ceim@iispv.cat), ref: 338/2025 | |
| Health condition(s) or problem(s) studied | Primary prevention of infertility. | |
| Intervention | The trial will be a two-group parallel randomized single-blind intervention study of 14 weeks duration that will be performed on healthy subjects (18-40 years) who, at baseline, followed a Western-style nutritional pattern. The trial will randomly assign participants (in a 1:1 ratio using computer-assisted randomization) to one of the following two interventions: 1) changing the usual Western-style diet to a Mediterranean diet (intervention group); or 2) following the usual Western-style diet (control group). | |
| Intervention type | Mixed | |
| Primary outcome measure(s) |
| |
| Key secondary outcome measure(s) |
| |
| Completion date | 31/12/2028 |
Eligibility
| Participant type(s) | Healthy volunteer |
|---|---|
| Age group | Adult |
| Lower age limit | 18 Years |
| Upper age limit | 40 Years |
| Sex | Male |
| Target sample size at registration | 126 |
| Key inclusion criteria | 1. Healthy subjects 2. Aged 18-40 years 3. Male 4. Follow a Western-style nutritional pattern |
| Key exclusion criteria | 1. Allergy to foods typical of the Mediterranean diet (nuts or traces thereof, extra virgin olive oil). 2. Presence of alcoholism, active drug dependence, or smoking (>5 cigarettes per day or equivalent). 3. Known history of hepatitis B or C, or HIV antibodies. 4. Any serious illness. 5. Cancer diagnosed within the last five years. 6. Active infectious disease. 7. High-grade inflammatory disease. 8. Scheduled surgery within the next 2 months after randomization. 9. Use of plant sterols, antihypertensive or antidiabetic medications, mineral supplements, fiber supplements, fish oil, or antioxidants. 10. Following vegetarian, macrobiotic, vegan, or similar diets for weight loss at the start of the study. 11. Weight loss of more than 5 kg in the past month. 12. Any type of disease in the reproductive history or vasectomy. 13. Use of medications associated with sperm abnormalities: antidepressants (paroxetine, citalopram, fluoxetine, sertraline, bupropion); calcium channel blockers (diltiazem, nifedipine); alpha-adrenergic blockers (tamsulosin, alfuzosin); antiepileptics (phenytoin, carbamazepine, valproate); antiretrovirals (HAART, saquinavir), etc. 14. Other medical or social conditions that may hinder adherence to the intervention or follow-up. |
| Date of first enrolment | 01/01/2026 |
| Date of final enrolment | 31/12/2028 |
Locations
Countries of recruitment
- Spain
Study participating centre
Reus
43201
Spain
Results and Publications
| Individual participant data (IPD) Intention to share | Yes |
|---|---|
| IPD sharing plan summary | Available on request |
| IPD sharing plan | The datasets generated during and/or analysed during the current study will be available upon reasonable request to the PI: Albert Salas-Huetos (albert.salas@urv.cat). |
Study outputs
| Output type | Details | Date created | Date added | Peer reviewed? | Patient-facing? |
|---|---|---|---|---|---|
| Statistical Analysis Plan | 30/12/2025 | No | No |
Additional files
- 48723_SAP.pdf
- Statistical Analysis Plan
Editorial Notes
23/12/2025: Study’s existence confirmed by the Pere Virgili Health Research Institute (Institut d’Investigació Sanitària Pere Virgili; IISPV) Research Ethics Committee (Comité Ético de Investigación con Medicamentos IISPV), Spain.
