Some early studies suggested that drinking cranberry juice could reduce recurrent UTIs. However, more recent higher quality research from 2012 found that there is no benefit in preventing UTIs compared to placebo or no treatment. This study was a review of 24 studies with 4473 participants and was carried out by the Cochrane Database of Systematic Reviews, which is a gold-standard level of research. Other findings were that:
- many people in the studies stopped drinking the juice, suggesting that it may be unacceptable to consume in the long term for many people
- cranberry-derived products (such as tablets or capsules) were also ineffective.
There have been two further randomised trials in 2016. One found no benefit in nursing home residents. Another study found a meaningless benefit of preventing one UTI per 3.2 years of daily drinking of cranberry juice, and the study had significant biases like being funded by a cranberry product manufacturer.