From the Guidelines
Cranberry products can help prevent urinary tract infections (UTIs) in women, children, and individuals susceptible to UTIs, and can be used as a preventive measure. The most recent and highest quality study, published in 2024 in JAMA Network Open 1, found that cranberry products containing proanthocyanidin levels of 36 mg can reduce the risk of recurrent UTIs in these populations.
Key Points to Consider
- Cranberry products are not recommended as the sole treatment for active UTIs, and antibiotics are necessary for treating infections 1.
- For prevention, cranberry supplements containing 36 mg of proanthocyanidins daily or 8-16 ounces of pure cranberry juice (not cocktail) daily can be used 1.
- Cranberry works by preventing bacteria, particularly E. coli, from adhering to the urinary tract lining.
- The evidence for the use of cranberry products in older adults, those with bladder emptying problems, or pregnant women is insufficient to make a clear recommendation for or against use 2.
- It is essential to stay well-hydrated, urinate after sexual activity, and practice good hygiene as additional preventive measures.
- People taking blood thinners should consult their doctor before using cranberry supplements due to potential interactions.
Additional Considerations
- Other strategies to prevent UTIs include continuous or postcoital antimicrobial prophylaxis, probiotics, vaginal estrogen, increased water intake, and methenamine hippurate 1.
- The decision to use antibiotic prophylaxis must balance the need for prevention against the risk of adverse drug events, antimicrobial resistance, and microbiome disruption 1.
From the Research
Cranberry for UTI Prevention
- Cranberry products have been widely used to prevent urinary tract infections (UTIs) due to their proanthocyanidin content, which inhibits the adherence of bacteria to the urothelial cells lining the bladder 3.
- A systematic review of 50 studies (8857 participants) found that cranberry products reduced the risk of UTIs in women with recurrent UTIs, children, and people susceptible to UTIs following interventions 3.
- The evidence suggests that cranberry products may be effective in reducing the risk of symptomatic, culture-verified UTIs, particularly in women with recurrent UTIs (RR 0.74, 95% CI 0.55 to 0.99) and children (RR 0.46, 95% CI 0.32 to 0.68) 3.
Cranberry for UTI Treatment
- A systematic review of three RCTs (n = 688) found that the current evidence base for or against the use of cranberry extract in the management of acute, uncomplicated UTIs is inadequate, and rigorous trials are needed 4.
- One RCT found that consumption of cranberry extract capsules was associated with a within-group improvement in urinary symptoms and Escherichia coli load at day 10 compared with baseline (p < 0.01) 4.
- Another study found that whole cranberry fruit powder (proanthocyanidin content 0.56%) could prevent recurrent UTI in women with two or more UTI episodes in the last year 5.
Mechanism of Action
- The anti-adhesive mechanism of cranberry-proanthocyanidins inhibits the docking of bacteria on tissues "in vitro" 6.
- The anti-adhesion effect of cranberry-proanthocyandins can also be applied for treatment of other common diseases of bacterial pathogenesis, e.g. Helicobacter pylori-associated gastritis and dental caries/periodontal disease 6.
- In vitro studies have shown that binding of the P fimbriae of Escherichia coli to the uroepithelial tissue can be inhibited in the presence of proanthocyanidins, the active ingredient of cranberries 7.