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Cranberry-containing products prevent UTI

Clinical Question:
Are cranberry-containing products effective in preventing urinary tract infections in women?

Bottom Line:
Cranberry-containing products, especially cranberry juice, are associated with protective effect against urinary tract infection (UTI), especially in women with frequent recurrence. Twice-daily use seems to be more effective than once-daily use. (LOE = 1a-)

Wang CH, Fang CC, Chen NC, et al. Cranberry-containing products for prevention of urinary tract infections in susceptible populations. A systematic review and meta-analysis of randomized controlled trials. Ann Intern Med 2012;172(13):988-996.  [PMID:22777630]

Study Design:
Meta-analysis (randomized controlled trials)

Self-funded or unfunded

Various (meta-analysis)

Two authors independently searched 3 databases, including the Cochrane Library, as well as bibliographies of relevant studies, assembling randomized controlled studies in any language that compared cranberry-containing products with other interventions to prevent UTI. Two authors independently selected studies for inclusion and entered the data. Study quality was assessed using the Cochrane Risk of Bias Tool. Ten studies enrolled a total of 1494 patients. There was no evidence of publication bias, though there was significant heterogeneity among the study results, which was removed after elimintaing the 2 studies that were outliers. Overall, the use of cranberry-containing products was effective in preventing UTI (relative risk = 0.62; 95% CI, .49-.80). The preventive effect is more pronounced in women with recurrent UTIs, women in general, and children. Cranberry juice seems to be more effective than other products (possibly because users also were more hydrated), as was twice daily administration of any cranberry product. As is typically the problem with dietary supplements, there is no standardization regarding the dose or bioavailability of active ingredients, which makes it difficult to determine which available products will produce results similar to those seen in the studies.


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