Purpose: Cranberry juice is widely consumed to improve urinary health; however, its effects on the urinary microbiome (urobiome) of healthy individuals are unclear. We aimed to investigate the effect of continuous consumption of cranberry juice on the urobiome of healthy adults. 

Methods: this randomized, double-blind, placebo-controlled crossover trial included 40 healthy adults (21 women and 19 men) who completed the study. Participants consumed 80 mL of either cranberry juice or a placebo daily for 4 weeks, followed by a 4-week washout period and crossover to the alternate intervention. The urobiome was analyzed by 16S rRNA gene sequencing. 

Results: At baseline, the urobiome composition differed significantly between men and women (PERMANOVA, P [ .015). Overall, alpha and beta diversities did not change significantly after either intervention. In women, cranberry juice consumption was associated with decreased relative abundance of the genus Lactobacillus (median: 28.4%-18.4%; P [ .025); however, this change was not significant following correction for multiple comparisons (q [ 0.25). No significant compositional changes were observed in men after the intervention. 

Conclusion: In this exploratory study, continuous cranberry juice consumption showed a potential to modulate the urobiome in a sex-specific manner. The observed trend toward decreased Lactobacillus abundance in women provides a basis for future, larger studies for validation and assessment of its clinical relevance for female urinary health.