A new review published came to the conclusion that any benefit of drinking the juice is likely to be extremely small and only for women with recurrent urinary tract infections (UTI).
While it isn't exactly clear why cranberry juice has been thought to be beneficial, some scientists suggest that certain sugars and flavanol compounds in cranberries prevent bacteria from sticking to cells lining the walls of the urinary tract.
In the review, researchers focused on cranberry juice and products as a prevention method for subjects with urinary or kidney infections, not as a treatment for an acute infection.
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.
Sticking to the daily routine is a major commitment, lead researcher Ruth Jepson of the University of Stirling in the UK told WebMD UK. "You do wonder in real life how many women would be prepared to drink that amount."