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.
Does ingestion of cranberry juice reduce symptomatic urinary tract infections in older people in hospital? A double-blind, placebo-controlled trial.
cranberry juice is often given to older people in hospital to prevent urinary tract infection (UTI), although there is little evidence to support its use.
                to assess whether cranberry juice ingestion is effective in reducing UTIs in older people in hospital.
                randomised, placebo-controlled, double-blind trial.
                Medicine for the Elderly assessment and rehabilitation hospital wards.
                376 older patients in hospital.
                participants were randomised to daily ingestion of 300 ml of cranberry juice or matching placebo beverage. The primary outcome was time to onset of first UTI. Secondary outcomes were adherence to beverage drinking, courses of antibiotics prescribed, and organisms responsible for UTIs.
                a total of 21/376 (5.6%) participants developed a symptomatic UTI: 14/189 in the placebo group and 7/187 in the cranberry juice group. These between-group differences were not significant, relative risk (RR) 0.51 [95% CI 0.21-1.22, P = 0.122). Although there were significantly fewer infections with Escherichia coli in the cranberry group (13 versus 4) RR 0.31 [95% CI 0.10-0.94, P = 0.027], this should be interpreted with caution as it was a secondary outcome.
                despite having the largest sample size of any clinical trial yet to have examined the effect of cranberry juice ingestion, the actual infection rate observed was lower than anticipated, making the study underpowered. This study has confirmed the acceptability of cranberry juice to older people. Larger trials are now required to determine whether it is effective in reducing UTIs in older hospital patients.