Cranberry juice is not likely to prevent bladder and kidney infections, according to a new study in Britain, which indicates that the advantages associated with it for curing such health issues were mythical.
Certain sugars and flavanol compounds in cranberries are believed to prevent bacteria sticking to cells lining the walls of the urinary tract.
Researchers from Stirling University analysed the very latest evidence and concluded that any benefit, if present at all, is likely to be small and only for women with recurrent urinary tract infections (UTI), the journal ‘The Cochrane Library’ reports.
They gathered together evidence from 24 studies that involved a total of 4,473 people. These studies included 14 added since the 2008 update, which concluded that cranberries offer a small benefit in preventing recurring UTIs in women.
“Now that we’ve updated our review with more studies, the results suggest that cranberry juice is even less effective at preventing UTIs than was shown in the last update,” said Ruth Jepson of the University of Stirling in Stirling, who led the study.
UTIs affect the bladder, as in cystitis, and sometimes the kidneys. Cranberries and cranberry juice have been used to prevent UTIs for decades, although it is not clear how they might help protect against infection, according to a Stirling statement.
Those in treatment groups were given cranberry juice, tablets or capsules, while those in control groups were given placebo cranberry products, water, methenamine hippurate, antibiotics, lactobacillus or nothing.
Although in some studies there were small benefits for women suffering from recurring infections, women would have to consume two glasses of cranberry juice per day for long periods to prevent one infection. The researchers conclude that current evidence does not support cranberry juice as a means of preventing UTIs.
In the studies where participants were given juice, there were large numbers of drop-outs, suggesting it might not be acceptable to drink over long time periods.
“We can’t see a particular need for more studies of the effect of cranberry juice, as the majority of existing studies indicate that the benefit is small at best, and the studies have high drop-out rates,” said Jepson.
Jepson RG, Williams G, Craig JC. Cranberries for preventing urinary tract infections. Cochrane Database of Systematic Reviews 2012, Issue 10. Art. No.: CD001321. DOI: 10.1002/14651858.CD001321.pub5.