Cranberries have been valued for their ability to reduce the risk of urinary tract infections for hundreds of years.

It acidifies the urine, contains an antibacterial agent called hippuric acid and also contains other compounds that reduce the ability of E. coli bacteria to adhere to the walls of the urinary tract. Before an infection can start, a pathogen must first latch on to and then penetrate the mucosal surface of the urinary tract walls, but cranberries prevent such adherence, so the E. coli is washed away in the urine and voided. Since E. coli is pathogen responsible for 80-90% of urinary tract infections, the protection afforded by cranberries is quite significant.