Cranberry is often recommended as an alternative therapy for cystitis and urinary tract infections (UTIs). Originally, complementary doctors thought that cranberry acidified the urine to create an antibacterial effect. Further research showed that patients would need to drink 1,500 mL (about 6-1/3 cups) to bring the urine’s pH to 5.5, the level that would kill bacteria. That’s a whole lot of cranberry juice.