What is the issue?

Cranberries (as cranberry juice, tablets or capsules) have been used for many years to prevent urinary tract infections (UTIs). Cranberries contain proanthocyanidins (PACs), substances that can prevent bacteria from sticking to the walls of the bladder. This may help prevent infections and reduce the need for working people to take time for medical appointments. However, there is currently no established regimen for what PACs dose to use and no formal regulation by health authorities of cranberry products. In particular, the dose suggested may not be included on the package.

What did we do?

We analysed the results of randomised controlled trials (RCTs), which compared the occurrence of UTIs in people taking a cranberry product with those taking a placebo or no treatment. We also analysed the results of RCTs comparing a cranberry product with other treatments such as antibiotics or probiotics.

What did we find?

We found 50 RCTs involving 8857 people. Forty-five RCTs compared cranberry with a placebo or no treatment. Taking cranberries as a juice, tablets or capsules reduced the number of UTIs in women with recurrent UTIs, in children with UTIs and in people susceptible to UTIs following an intervention such as bladder radiotherapy. However, UTIs did not appear to be reduced in elderly institutionalised men and women, in adults with neuromuscular bladder dysfunction and incomplete bladder emptying, or in pregnant women. Few people reported any side effects with the most common being tummy pain. We did not find enough information to determine if cranberry products are more or less effective compared with antibiotics or probiotics in preventing further UTIs.

Conclusions

Cranberry products may help to prevent UTIs which cause symptoms in women with frequent UTIs, in children with UTIs and in people who have undergone an intervention involving the bladder. However, further assessment is required in well-designed and prospectively registered RCTs to clarify further who with UTIs would benefit from cranberry products.