Clinical question
Are cranberry products effective for preventing urinary tract infections (UTIs)?
Bottom line
The current body of evidence suggests cranberry products (either in juice or as tablets or powder), compared with placebo or no treatment, probably reduce the risk of symptomatic UTIs in women with recurrent UTIs, in children, and in people at risk of UTIs following an intervention.
The data did not support the use of cranberry products to reduce the risk of symptomatic UTIs in older men and women, in pregnant women, or in adults with neuromuscular dysfunction of the bladder and incomplete bladder emptying. However, data in these latter groups are limited to small studies with considerable uncertainty around the results.
Caveat
Only one small study compared cranberry tablets with cranberry juice and found there may be little or no difference in efficacy between tablets and juice. However, comparisons of cranberry juice or tablets or powder with placebo or control raised the possibility that tablets may be more effective than juice – almost all point estimates suggested a greater benefit in the various populations taking tablets compared with placebo or control.
It also remains unclear what the optimum dose of cranberry and its active ingredient should be.
Context
Cranberries (particularly in the form of cranberry juice) have been used widely for several decades for the prevention and treatment of UTIs. Current theory suggests cranberries prevent bacteria (particularly Escherichia coli) from adhering to the uroepithelial cells lining the bladder wall. Proanthocyanidins are believed to be the active ingredient of cranberry products, so it is probable that the amount of PAC in a product determines the efficacy of that product.
Cochrane Systematic Review
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