Prior to the current update it appeared there was some evidence that cranberry juice may decrease the number of symptomatic UTIs over a 12 month period, particularly for women with recurrent UTIs. The addition of 14 further studies suggests that cranberry juice is less effective than previously indicated. Although some of small studies demonstrated a small benefit for women with recurrent UTIs, there were no statistically significant differences when the results of a much larger study were included. Cranberry products were not significantly different to antibiotics for preventing UTIs in three small studies. Given the large number of dropouts/withdrawals from studies (mainly attributed to the acceptability of consuming cranberry products particularly juice, over long periods), and the evidence that the benefit for preventing UTI is small, cranberry juice cannot currently be recommended for the prevention of UTIs. Other preparations (such as powders) need to be quantified using standardised methods to ensure the potency, and contain enough of the 'active' ingredient, before being evaluated in clinical studies or recommended for use.
Cranberry juice for the prevention of recurrent urinary tract infections: a randomized controlled trial in children.
This study compares the effects of daily cranberry juice to those of Lactobacillus in children with recurrent urinary tract infections (UTIs).
                Eighty-four girls aged between 3 and 14 years were randomized to cranberry, Lactobacillus or control in three treatment arms: G1, cranberry juice 50 ml daily (n=28); G2, 100 ml of Lactobacillus GG drink on 5 days a month (n=27); and G3, controls (n=29). The study lasted for 6 months.
                Only four subjects withdrew: 1/28 (3.5%) from G1, 1/27 (3.7%) from G2 and 2/29 (6.8%) from G3, because of poor compliance to the established protocol. There were 34 episodes of UTIs in this cohort: 5/27 (18.5%) in G1, 11/26 (42.3%) in G2 and 18/27 (48.1%) in the G3, with at least one episode of infection (p<0.05).
                These data suggest that daily consumption of concentrated cranberry juice can significantly prevent the recurrence of symptomatic UTIs in children.