26 October 2012
Cranberry juice now gets a ‘thumbs down’ from Cochrane reviewers* for prevention of urinary tract infection (UTI).
The Cochrane renal group, which includes Professor Jonathan Craig from the Centre for Kidney Research at The Children’s Hospital, Westmead, has backed away from its cautious support in 2008 for the benefits of cranberry.
At that time, the researchers said there was some evidence that cranberry juice may decrease the number of symptomatic UTIs, particularly for women suffering from recurrent infections.
However the new systematic review of a total of 24 studies with nearly 4500 participants found no statistically significant evidence that cranberry products, including capsules, reduced UTIs when compared with placebo (dummy treatment), water or no treatment.
“Cranberry juice cannot currently be recommended for the prevention of UTIs,” the group wrote.
The authors noted that many studies reported low compliance in participants, suggesting that drinking a lot of cranberry juice becomes less appealing over time. A commonly recommended amount for UTI prevention was 300ml of juice per day, they said.
The authors noted that cranberry tablets and capsules had even less backing than juice, as processing of the berries could reduce the purported active ingredient – substances called proanthocyanidins – to almost nothing.
The protective mechanism of cranberry has not been established but it has been theorised that proanthocyanidins inhibit bacteria such as E. coli from adhering to the cells lining the wall of the bladder.
*Cochrane reviews are conducted by the Cochrane Collaboration, an international organisation aimed at helping people make well-informed decisions about healthcare by undertaking scientific reviews of evidence for certain treatments.
Last Reviewed: 26 October 2012