Prospective study on the effects of regular and decaffeinated coffee on urinary symptoms in young and healthy volunteers

Aims: Coffee reduction has been a strategy to prevent urinary symptoms with conflicting evidence. We aimed to study the effects of regular and decaffeinated coffee on urinary symptoms among low and frequent coffee users, who were young and healthy.

Methods: We conducted a double-blinded parallel study on subjects, who were restricted from consuming caffeinated items outside the study. After subjects completed 5 days of caffeine abstinence they consumed regular coffee (450 mg/d caffeine content) or decaffeinated coffee (12 mg/d caffeine content) for 5 days. Previous caffeine use and urinary symptoms were assessed by a diet survey, urogenital distress inventory, and interstitial cystitis problem and symptom indices (ICPI, ICSI).

Results: Forty nine subjects completed the study. When assessing the submeasures "frequency" and "urgency" on ICPI and ICSI subjects drinking coffee reported a significant increase in urgency (P < 0.05) and frequency (P < 0.05), whereas subjects drinking decaffeinated coffee experienced no difference in those submeasures in comparison to no caffeine intake. However, previous "low coffee users" experienced the largest increase of urinary symptoms, whereas previous "frequent coffee users" showed fewer symptoms when exposed to regular coffee.

Conclusions: The study suggests that avoiding high-dosage coffee consumption prevents urgency and frequency, which supports recommendations to limit caffeinated beverages. The study differentiates between subjects having a history of low and frequent coffee use. Subjects, who are not used to regular coffee consumption, seem to be more vulnerable to the effects of coffee on urinary symptoms. Better understanding of the effects of coffee on urinary symptoms may improve patients counseling. Neurourol. Neurourol. Urodynam. 36:432-437, 2017. © 2015 Wiley Periodicals, Inc.