Background: Cranberries (particularly in the form of cranberry juice) have been used widely for several decades for the prevention and treatment of urinary tract infections. The aim of this review is to assess the effectiveness of cranberries in treating such infections.
Objectives: To assess the effectiveness of cranberries for the treatment of urinary tract infections.
Search strategy: The search strategy developed by the Cochrane Renal Group was used. Also, companies involved with the promotion and distribution of cranberry preparations were contacted; electronic databases and the Internet were searched using English and non English language terms; reference lists of review articles and relevant trials were also searched.
Selection criteria: All randomised or quasi randomised controlled trials of cranberry juice or cranberry products for the treatment of urinary tract infections. Trials of men, women or children were included.
Data collection and analysis: Titles and abstracts of studies that were potentially relevant to the review were screened by one reviewer, RJ, who discarded studies that were clearly ineligible but aimed to be overly inclusive rather than risk losing relevant studies. Reviewers RJ and LM independently assessed whether the studies met the inclusion criteria. Further information was sought from the authors where papers contained insufficient information to make a decision about eligibility.
Main results: No trials were found which fulfilled all of the inclusion criteria. Two trials were excluded because they did not have any relevant outcomes.
Reviewer's conclusions: After a thorough search, no randomised trials which assessed the effectiveness of cranberry juice for the treatment of urinary tract infections were found. Therefore, at the present time, there is no good quality evidence to suggest that it is effective for the treatment of urinary tract infections. Well-designed parallel group, double blind trials comparing cranberry juice and other cranberry products versus placebo to assess the effectiveness of cranberry juice in treating urinary tract infections are needed. Outcomes should include reduction in symptoms, sterilisation of the urine, side effects and adherence to therapy. Dosage (amount and concentration) and duration of therapy should also be assessed. Consumers and clinicians will welcome the evidence from these trials.