Surely you’ve heard that cranberry juice will prevent urinary tract infections. There are even some old studies that seem to support this belief. A new systematic review has made that much less clear:
Urinary tract infections (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 one theory, certain sugars and flavanol compounds in cranberries prevent bacteria sticking to cells lining the walls of the urinary tract. Several systematic reviews have been published on the subject in The Cochrane Library, each time incorporating more evidence. In the last review in 2008, it was concluded that cranberries offer a small benefit in preventing recurring UTIs in women.
In the current review, the researchers gathered together evidence from 24 studies that involved a total of 4,473 people. These studies included 14 added since the 2008 update. 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.
No one is going to drink two glasses of cranberry juice a day for a long time for a very, very small chance of preventing a urinary tract infection. In fact, it appears that there were large numbers of women dropping out of studies requiring that much cranberry juice consumption.
This all warms my mythbusting heart. I can’t find the link to the systematic review yet. When I do, I’ll post it.