Inclusion Criteria:
* Female, post-menopausal, age ≥ 55 years old
* Diagnosis of recurrent UTI, defined as ≥ 3 symptomatic culture-proven UTI episodes in 12 months or ≥ 2 in 6 months.
* Currently free from a UTI determined based on absence of symptoms as determined by the UTI symptom assessment questionnaire79 and negative urine culture (\<103 colony forming units per ml of urine).
* Able to attend all follow-up appointments for the study.
* A negative upper and lower urinary tract evaluation, including pelvic examination for pelvic organ prolapse (less than stage 2), measurement of post-void residual (less than 50 ml), and imaging (renal ultrasound and standing voiding cystourethrogram) to exclude kidney stone, hydronephrosis, reflux, or urethral diverticulum.
Exclusion Criteria:
* Current use of D-mannose. Patients willing to stop taking D-mannose will be offered to join the trial after a 4-week wash-out period.
* Complicated UTIs, including need for catheter drainage or intermittent catheterization, neurogenic bladder, bladder augmentation, or urinary diversion.
* Ongoing supplement use (Box 1). Patients willing to stop taking the listed supplements will be offered to join the trial after a 4-week wash-out period.
* Evidence of upper tract infection (pyelonephritis), including temperature higher than 38°C, flank/lumbar pain or tenderness
* Diagnosis of interstitial cystitis or overactive bladder syndrome
* Prophylactic antibiotics started in the last 3 months and unwilling to discontinue, or intention to start in the next 12 months
* Use of Uromune or other vaccine approaches to reduce rUTI
* Participation in a research study involving an investigational product in the past 12 weeks
* Receipt of phage treatment
* History of chronic diarrhea requiring regular therapy
* Inability to swallow or known history of gastrointestinal malabsorption
* History of recurrent vaginal yeast infections
* Systemic disease precluding enrollment in this study (uncontrolled diabetes with HgA1C above 7, ongoing chemotherapy or immunotherapy, renal insufficiency \[creatinine \> 1.5 g/dl\]), mental or cognitive impairment, weight loss diet requiring excessively large amounts of fluid intake, or other health-related specific diet).
* Nursing home resident
* BMI \>40
Box 1 Supplements to avoid
* Multi-Vitamins and Multi-Mineral capsules
* Specific Vitamins or Minerals (e.g., Calcium, Citrical, Calcium Gummies, Vitamin A, D, Niacin, Pyridoxine, Selenium, Vitamin E, B6, Iron, Omega 3, D3, Magnesium, B-Complex, Women's Ultra MultiVitamin, GNC B-Complex, B-12, PreserVision Areds2, Vitamins D, B Pollen)
* Probiotics
* Cranberry Mannose or Cranberry Extract Weight loss products to avoid
* Medifast
* Vitafusion
* OptiVin Products
* Appetite Suppressants
* Keto-Fuel
