Ask Mary

Men and women who have never had a UTI should not feel compelled to drink cranberry juice - although it won't hurt.  To prevent urinary tract infections, it is unclear exactly how much cranberry juice a woman should drink.  In various studies, effective doses of pure cranberry juice (not cranberry juice drink) have ranged from 5 oz to 24 ounces a day.  A study on humans published in JAMA found that 8 oz of cranberry juice cocktail was enough to prevent 79% of antibiotic resistant bacteria from sticking to urinary tract cells for up to 10 hours; however, a review article published in American Family Physician recommended an 8 ounce dose of pure unsweetened cranberry juice three times daily for UTI prevention.