Cranberry and urinary tract infections

Cranberry's ability to prevent urinary tract infections remains unconfirmed, but ANSES remains attentive to the subject

The term "urinary tract infection” (UTI) covers a heterogeneous group of infections occurring more frequently in women than in men, with 40 to 50% of women having at least one UTI during their lifetime. The bacterium Escherichia coli (E. coli) is the pathogen most frequently responsible for UTIs in women 15 to 65 years of age (80% of cases). Questions have been raised repeatedly about the possibility of using cranberry and products containing it to prevent UTIs. Various risk assessment agencies have examined cranberry in the areas of both nutrition and health products. While the effectiveness of cranberry in preventing urinary tract infections has not yet been proven, ANSES is monitoring scientific developments on the subject..

The question of using cranberry and products containing it to prevent UTIs has often been raised. And so between 2003 and 2008 the French Food Safety Agency (AFSSA) assessed various cranberry products for which claims had been made suggesting a direct link between consumption of cranberry and prevention of UTIs.

In 2008, ANSM (originally AFSSAPS) addressed this issue in its guidelines entitled Diagnostic et antibiothérapie des infections urinaires bactériennes communautaires chez l'adulte ["Diagnosis and antibiotic treatment of community-acquired bacterial urinary tract infections in adults"].

Between 2009 and 2013, EFSA assessed various claims that the consumption of products containing cranberry (beverages, dried fruit) or cranberry extracts (food supplements) had a beneficial effect on urinary tract function.

All these assessments are consistent and indicate that cranberry products reduce the adherence of certain UTI-causing bacteria to the urinary tract walls.

Experimental studies do indeed show that cranberry products (juice, cocktails or juice extracts) or urine from subjects who consumed these products inhibit the adherence of certain E. coli bacteria to uroepithelial cells. This effect is related to the presence in cranberry products of antioxidants called proanthocyanidins (PACs) that are responsible for the anti-adherence effect.

However, the data - which include clinical data (from patient monitoring) - are currently insufficient to conclude that consumption of cranberry, or products containing it, has any preventive effect on UTIs.

ANSES's work

In this context, the Agency wanted to update its work in order to determine if new studies would provide details regarding the effect of cranberry consumption on the prevention of urinary tract infections. This assessment also provides details on the framework for use of the claim it validated in 2003, thus preventing improper or inappropriate use.

In its opinion, ANSES reviewed ten studies that were published since the preceding opinions were issued. The work confirms the conclusions that the Agency issued previously. ANSES notes that clinical trials assessing the effect of cranberry consumption often contain methodological flaws, in particular an insufficient number of subjects and/or no placebo.  Considering the potential interest of cranberry should its effect on urinary tract infection prevention be proven, ANSES plans to continue monitoring scientific developments on the topic.