Cranberries contain a substance that can prevent bacteria from sticking to the walls of the bladder. This may help reduce bladder and other urinary tract infections (UTIs). Cranberries (usually as cranberry juice) have been used to try and treat UTIs, particularly in high-risk groups such as older people. Cranberries have few adverse effects. This review found no studies reporting the effects of cranberry juice or other cranberry products on the treatment of UTIs.
Read the full abstract
Cranberries (particularly in the form of cranberry juice) have been used widely for several decades for the prevention and treatment of urinary tract infections (UTIs). 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 UTIs.
Search strategy
We searched the Cochrane Kidney and Transplant Register of Studies up to 1 August 2023 through contact with the Information Specialist using search terms relevant to this review. Studies in the Register are identified through searches of CENTRAL, MEDLINE, and EMBASE, conference proceedings, the International Clinical Trials Registry Portal (ICTRP) Search Portal and ClinicalTrials.gov.
Selection criteria
All randomised controlled trials (RCTs) or quasi-RCTs of cranberry juice or cranberry products for the treatment of UTIs. Studies of men, women or children were to be included.
Data collection and analysis
Titles and abstracts of studies that were potentially relevant to the review were screened and studies that were clearly ineligible were discarded. Further information was sought from the authors where papers contained insufficient information to make a decision about eligibility.
Main results
No studies were found that fulfilled all of our inclusion criteria. Seven studies were excluded because they were the wrong study design, mixed interventions or did not report any relevant outcomes. One study is ongoing; however, its current status is unknown.
Authors' conclusions
After a thorough search, no RCTs which assessed the effectiveness of cranberry juice for the treatment of UTIs were found. Therefore, at the present time, there is no good quality evidence to suggest that it is effective for the treatment of UTIs. Well-designed parallel-group, double-blind studies comparing cranberry juice and other cranberry products versus placebo to assess the effectiveness of cranberry juice in treating UTIs are needed. Outcomes should include a reduction in symptoms, sterilisation of the urine, side effects and adherence to therapy. The dosage (amount and concentration) and duration of therapy should also be assessed. Consumers and clinicians will welcome the evidence from these studies.
