Inclusion Criteria:  Age: ≥18 and <40 years old. Spermatozoa concentration >15 x 10⁶ /mL in all sperm analysis performed in the last 24 months. Spermatozoa mobility >32% in all sperm analysis performed in the last 24 months. Spermatozoa morphology >4% in all sperm analysis performed in the last 24 months. Signed and dated informed consent  Exclusion Criteria:  Use of antibiotics, intravenous illicit drugs, chemotherapy or radiotherapy usage in the last 3 months. Active smoking (during the preceding 12 months). More than 3 days prior to the last ejaculation.