Cranberry Products for Preventing Urinary Tract Infections
Benefits in NNT
16
1 in 16 women with recurrent UTIs were helped
8
1 in 8 children were helped
9
1 in 9 people with susceptibility to UTI due to a bladder intervention were helped
Harms in NNT
No apparent difference in harms
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Source
Johari F, Johari P. Cranberry products for preventing urinary tract infections. afp. 2024;110(1):23A-23B.Study Population: 50 trials including 8,857 patients considered susceptible to recurrent urinary tract infections (UTIs)
Efficacy Endpoints
Number of participants with symptomatic, culture-verified UTIsHarm Endpoints
Adverse events (e.g., gastrointestinal problems)Narrative
UTIs affect more than 150 million individuals globally each year and impose a substantial financial burden on health care systems.1 The annual incidence of acute uncomplicated UTIs reaches 7% among women of all ages, and 30% of these women may experience a recurrence within 6 to 12 months.2, 3For decades, cranberry products have been used in the treatment and prevention of UTIs. Cranberries' mechanism of action uses proanthocyanidins, which inhibit the adherence of p-fimbriated bacteria (e.g., Escherichia coli) to urothelial cells.4 The systematic review and meta-analysis discussed here explores the effectiveness of cranberry products in preventing UTI.
The Cochrane review included 50 randomized controlled trials (N = 8,857) and compared cranberry products with placebo, no treatment, or other interventions (e.g., antibiotics, probiotics) for prevention of UTI.5 The review focused on six populations that are susceptible to UTI: women with recurrent UTI (usually two or more in the past 12 months), older men and women in institutions, pregnant women, children, adults with neuromuscular dysfunction of the bladder and incomplete bladder emptying, and people susceptible to UTIs following an intervention (e.g., bladder radiotherapy, urogenital surgery, kidney transplantation).5
The Cochrane review showed moderate-certainty evidence that compared with placebo or control (water or nonspecific treatment), cranberry products reduced the risk of UTI in women with a history of recurrent UTI (risk ratio [RR] = 0.74; 95% CI, 0.55 to 0.99; absolute risk reduction [ARR] = 6.3%; number needed to treat [NNT] = 16) and in children (RR = 0.53; 95% CI, 0.36 to 0.78; ARR = 13.6%; NNT = 8). The review showed low-certainty evidence of benefit for those susceptible to UTI due to an intervention (RR = 0.47; 95% CI, 0.37 to 0.61; ARR = 12.2%; NNT = 9). However, in older men and women who are institutionalized, pregnant women, and adults with neuromuscular bladder dysfunction with incomplete bladder emptying, no apparent treatment benefit was observed.5
The most commonly reported harms associated with cranberry products were gastrointestinal adverse effects; moderate-certainty evidence demonstrated no difference between the groups.
Caveats
The trials used different cranberry forms (i.e., juice, tablet, capsule) and amounts; therefore, there is no consensus dose of proanthocyanidins for UTI risk reduction. The available information is derived from small-scale studies, which introduces uncertainty. Statistical heterogeneity among the trials was mostly low or moderate. Approximately one-half of the trials reported intervention compliance rates, and no apparent relationship was found between compliance and the efficacy end points.5About one-half of the trials in the review demonstrated low risk of bias, with selection bias noted as the major issue. Most of the included trials compared cranberry products with no treatment, water, or placebo. The Cochrane review found insufficient data to compare cranberry products with antibiotics or probiotics for UTI risk reduction.4
The original manuscript was published in Medicine by the Numbers, American Family Physician as part of the partnership between TheNNT.com and AFP.
Author
Fatima Johari, MD; Paniz Johari, MDSupervising Editors: Shahriar Zehtabchi, MD