Can cranberry prevent UTIs?

Debbie, a woman in her early 30s, sat down in my room.

She smiled but appeared a little uncomfortable in the consulting room: “Michael, I think I have another bladder infection.”

She had typical symptoms; dipstick urinalysis demonstrated blood and nitrites. Her last UTI was two years ago. As we were finishing the consultation, Debbie asked: “Should I be taking cranberry juice?”

What evidence exists?

Step 1: The Cochrane Library

Search term: “cranberry” reveals a hit, however, the conclusion suggests weakness in the evidence base (in 2008).1

“There is some evidence that cranberry juice may decrease the number of symptomatic UTIs over a 12-month period... the large number of dropouts/withdrawals indicates that