Sometimes it can be difficult to determine whether simple approaches often dismissed as “old wives’ tales” are helpful or useless. New scientific findings often tend to support such wisdom as “eat your vegetables” or “fish is brain food.” What about the advice to drink cranberry juice to manage painful urinary tract infections? Scientists are still trying to figure that one out.
Does It Help to Drink Cranberry Juice?
Q. I think that preventive medicine is good medicine. I have had frequent bouts of cystitis. It occurred to me to try prevention to see if it would reduce the frequency of my urinary tract infections.
In the past, when I would develop symptoms such as urgent painful urination, I was told to drink cranberry juice. I started following that suggestion before I got an infection.
Since I started drinking cranberry juice every day, I have had no infections. In addition my blood pressure is better. Am I mistaken that cranberry juice is responsible?
Cranberry Juice Controversy:
A. Cranberry juice has long been controversial for preventing or treating urinary tract infections (UTIs). A study published in JAMA found that cranberry capsules were no better than placebo in preventing bacteria in the urine of nursing home residents (Nov. 8, 2016). In another study, however, scientists found that women at higher than usual risk for recurrent UTIs were 40 percent less likely to experience an infection when they were drinking cranberry juice (Maki et al, Journal of the American College of Nutrition, Feb. 2018). This appears more relevant to the question of whether people who drink cranberry juice are less likely to suffer cystitis (a condition associated with infection that produces painful, urgent urination).
There is also research to suggest that ingredients in cranberries improve blood vessel flexibility, which may lower blood pressure (Rodriguez-Mateos et al, Molecular Nutrition & Food Research, Oct. 2016).
Too Much Sugar?
More than one reader has objected to cranberry juice because it is highly sweetened. A motivated individual can locate unsweetened cranberry juice, but drinking it every day might become a challenge. Excess sugar is excreted in the urine (Intemann et al, European Journal of Nutrition, online March 6, 2018). We have not been able to discover whether that promotes urinary tract infections in people who do not have diabetes.
