Background High prevalence of urinary tract infections (UTI), including cystitis, and concern for antimicrobial resistance justify safe and effective nonantibiotic therapies for prevention of recurrent UTI (rUTI). 

Objectives This study investigated the effect of a whole cranberry fruit powder supplement on incidence of culture-confirmed UTI (primary outcome) in females with rUTI history. 

Methods This multicenter, 6-mo, randomized, placebo-controlled, double-blind study enrolled 150 healthy females [18–65 y, body mass index (BMI) >17.5 and <35 kg/m2] with rUTI defined as ≥3 UTIs in the last year or ≤2 UTIs in the last 6 mo, excluding those with >5 UTIs in the last 6 mo. Participants consumed either 1 capsule of 500 mg/d of whole cranberry powder (Pacran) or placebo. Culture-confirmed UTIs (>108cfu/L) were assessed throughout the intervention period at unscheduled clinic visits whenever participants experienced UTI symptoms and at baseline, 3- and 6-mo clinic visits. Symptomatic suspected UTIs were defined as participant-reported UTI-associated symptoms at unscheduled visits. 

Results Whole cranberry powder capsules reduced culture-confirmed UTI risk compared with placebo by 52% (adjusted relative risk [RR]: 0.48; 95% confidence interval [CI]: 0.26, 0.87; P = 0.01); reduced Escherichia coli UTIs (RR: 0.49; 95% CI: 0.24, 1.01; P = 0.05); reduced incidence of UTI with urinary frequency and urgency symptomatology (RR: 0.29; 95% CI:0.13, 0.63; P < 0.01); delayed time to first UTI episode (adjusted hazard ratio [HR]: 0.36; 95% CI: 0.18, 0.74; P = 0.01); and reduced the mean total number of UTIs per participant (adjusted incidence rate ratio IRR: 0.41; 95% CI: 0.21, 0.79; P = 0.01). Significant differences between groups in incidence of symptomatic suspected UTIs and culture-confirmed dysuria were not observed. Exploratory scores for UTI-related female sexual matters, assessed in a subset of sexually active, consenting females, did not differ significantly between groups. No safety concerns were reported. 

Conclusion This study shows that whole cranberry powder capsules do not impact safety markers and reduce the incidence of culture-confirmed UTI and several other UTI-related outcomes in healthy females with rUTI history.