Cranberries for the prevention of urinary tract infections.

Data included in the meta-analyses (Fig. 1) showed that, compared with placebo, water or no treatment, cranberry products did not significantly reduce the occurrence of symptomatic urinary tract infection (UTI) overall (RR 0.86, 95% CI 0.71–1.04) or for any of the subgroups: women with recurrent UTI (RR 0.74, 95% CI 0.42–1.31); older people (RR 0.75, 95% CI 0.39–1.44); pregnant women (RR 1.04, 95% CI 0.97–1.17); children with recurrent UTI (RR 0.48, 95% CI 0.19–1.22); cancer patients (RR 1.15 95% CI 0.75–1.77); or people with neuropathic bladder or spinal injury (RR 0.95, 95% CI: 0.75–1.20). Overall, there were moderate differences in findings across trials (measured by heterogeneity I = 55%). Gastrointestinal side effects were no more or less likely from cranberry products compared with placebo/no treatment (RR 0.83, 95% CI 0.31–2.27). Many studies reported low compliance and high withdrawal/dropout problems which they attributed to palatability/acceptability of the products, primarily the cranberry juice. Most studies of other cranberry products (tablets and capsules) did not report how much of the ‘active’ ingredient the product contained, and therefore the products may not have had enough potency to be effective.