The influence of cranberry extract on recurrent urinary tract infections was investigated in a prospective and uncontrolled exploratory study. Women suffering from recurrent uncomplicated urinary tract infections were included in the study. The aim of the study was to observe and evaluate the effects on the number of urinary tract infections after administration of cranberry extracts within a 6-month prospective observation period compared to a 6-month retrospective period without dietary supplements. Twenty-three women were enrolled in the study. Participants reported 2.2 to 0.8 UTIs (at baseline) in the previous 6 months. After 6 months of cranberry use, the participants reported a significant decrease to 0.5 – 0.9 UTIs. The number of antibiotic treatments was also significantly reduced by 68% during the 6-month cranberry intake compared to 6 months retrospectively.
Aim: Cranberries (Vaccinium macrocarpon) are traditionally used to prevent urinary tract infections (UTIs). The authors’ aim was to investigate the effects of a dietary supplement containing cranberry extract, pumpkin seed extract, vitamin C and vitamin B2 on recurrent uncomplicated UTIs in women and their gut microbiota. Methods: A prospective, uncontrolled exploratory study was conducted in women with recurrent uncomplicated UTIs. The primary exploratory outcome was the number of UTIs in a 6-month prospective observation period compared to a 6-month retrospective period. Other outcomes were the number of antibiotics, quality of life (SF-36), intestinal microbiota (assessed by 16S rRNA amplicon sequencing) and assessment questions. Parameters were assessed at baseline and after 1, 2 and 7 months (starting cranberry supplement use after 1 month for 6 months). p-values were calculated using the pairwise Wilcoxon signed-rank test for one diversity and multivariate permutation analysis of variance. Results: Twenty-three women were enrolled in the study. Participants reported 2.2 to 0.8 UTIs (at baseline) in the previous 6 months. After 6 months of cranberry use, the participants reported a significant decrease to 0.5 – 0.9 UTIs (p < 0.001). The number of antibiotic treatments was also significantly (p < 0.001) reduced by 68% (0.14 - 0.35) during the 6-month cranberry intake compared to 6 months retrospectively (1.14 - 0.71). The SF-36 score for the physical component increased from 44.9 - 5.5 at baseline to 45.7 - 4.6 after 7 months (p=0.16). The SF-36 score for the mental component decreased slightly from a baseline value of 46.5-6.5 to 46.2-6.4 after 7 months (p = 0.74). No significant mean changes were observed for a- and b-diversity within the gut microbiota at genus, family or species level. In the evaluation questions, participants rated the cranberry extract positively and considered it beneficial. The supplement was safe to take. Conclusions: This study shows that women with recurrent uncomplicated urinary tract infections benefit from taking cranberries. Future larger clinical trials with further investigation of mechanisms of action are needed to determine the effects of cranberries on participants with uncomplicated UTIs.