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Cranberry Products for Preventing Urinary Tract Infections

Cranberry products were associated with preventing UTIs

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
16
6.25% of women with recurrent UTIs were helped
8
12.5% of children were helped
9
11% of people with susceptibility to UTI due to a bladder intervention were helped

Harms in NNT

No apparent difference in harms
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 UTIs

Harm 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, 3

For 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.5

About 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, MD
Supervising Editors: Shahriar Zehtabchi, MD

Published/Updated

November 21, 2024

References:

Flores-Mireles AL, Walker JN, Caparon M, Hultgren SJ. Urinary tract infections: epidemiology, mechanisms of infection and treatment options. Nat Rev Microbiol. 2015;13(5):269-284.
Giesen LGM, Cousins G, Dimitrov BD, van de Laar FA, Fahey T. Predicting acute uncomplicated urinary tract infection in women: a systematic review of the diagnostic accuracy of symptoms and signs. BMC Fam Pract. 2010;11:78.
Epp A, Larochelle A, UROGYNAECOLOGY COMMITTEE, FAMILY PHYSICIANS ADVISORY COMMITTEE. Recurrent urinary tract infection. J Obstet Gynaecol Can. 2010;32(11):1082-1090.
Howell AB, Botto H, Combescure C, et al. Dosage effect on uropathogenic Escherichia coli anti-adhesion activity in urine following consumption of cranberry powder standardized for proanthocyanidin content: a multicentric randomized double blind study. BMC Infect Dis. 2010;10:94.
Williams G, Hahn D, Stephens JH, Craig JC, Hodson EM. Cranberries for preventing urinary tract infections. Cochrane Database Syst Rev. 2023;4(4):CD001321.

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