Elucidating the Metabolic Impact of Isocaloric, Controlled, Mediterranean-Type Diets in Treatment-Naïve Men With Prostate Cancer on Active Surveillance (DINE Study)

Inclusion Criteria: * Males ≥18 years old * High suspicion of prostate cancer (PCa) per urologist's clinical evaluation * BMI \>18.5 * No prior PCa diagnosis or hormonal therapy (-ies) * Ability to read, write, speak, and understand English * Ability to provide informed consent * Candidate for and elects active surveillance (AS) if diagnostic biopsy is positive * Willingness to consume provided dietary interventions * Adequate organ and marrow function: White blood cell count (WBC) ≥2,500/mcL, Absolute neutrophil count (ANC) ≥1,500/mcL, Platelets ≥100,000/mcL, Hemoglobin ≥9 g/dL (transfusions permitted), Total bilirubin ≤1.5 x the institutional upper limit of normal (ULN) (for subjects with Gilbert's disease ≤3.0 mg/dL), Aspartate aminotransferase (AST)/Alanine aminotransferase (ALT) ≤2.5 x institutional ULN, Creatinine clearance ≥51 ml/min as defined by Cockcroft-Gault equation Exclusion Criteria: * Currently consuming a Mediterranean, lower carbohydrate, ketogenic, vegan, vegetarian, high fiber diet (14g fiber \> per 1,000 Calories) and/or any supplements (including herbal), vitamins, minerals, that would interfere with diets being tested in the study as determined by dietitian and/or investigators. * Previous intolerability to fiber-rich diets * Colitis, Irritable Bowel Syndrome, or other gastrointestinal condition per clinician discretion * Unwilling to undergo transperineal PCa biopsies * Food allergies or other major dietary restrictions * Receiving active medical treatment for Type I or Type II diabetes mellitus * Prior antibiotic usage (i.e. within last 30 days) at time of consent * Recent weight loss (both intentional and unintentional) as defined by 5%+ body weight in the last 30 days * Undergone any type of weight loss surgery * Any medical contraindications as determined by investigators * High risk as defined by PSA≥20 and/or PI-RADS 5 lesion as per clinician evaluation * History of diabetic ketoacidosis * Gout * Patients that are immunosuppressed (transplant history, on immunosuppression, etc.) as per clinician discretion * Recent (within last 30 days) device implant/joint requiring antibiotics as per clinician determination * Prior history of prostate biopsy infection * Uncontrolled hypertension as defined by blood pressure greater than 140/80 (with or without medication) * Gallbladder removed or plan to remove per clinician evaluation * Other malignancies actively receiving systemic treatment as per clinician evaluation