Drinking more cranberry juice may help prevent urinary tract infections

Drinking more cranberry juice may be better for staving off urinary tract infections than drinking less, according to a UW study. Results of the study were presented at the 42nd annual meeting of the Infectious Diseases Society of America.

Researchers discovered that a type of tannin found in cranberries and blueberries interacts with the tips of hairs on Escherichi coli (E. coli) bacteria, and prevents them from sticking to the bladder walls and causing an infection.

Study volunteers had their urine collected before and after drinking cranberry juice cocktail. E. coli were incubated in the urine samples and combined with human bladder cells. In women consuming juice, the number of bacteria sticking to bladder cells was significantly lower. Also, women consuming eight ounces had a two-fold increase in the benefits of drinking cranberry juice compared to women consuming four ounces.

A grant from the National Center for Complementary and Alternative Medicine, one of the National Institutes of Health, is funding a study of the duration of the juice's benefits. Researchers are also examining the effects of additional doses of juice and concurrent food ingestion.

Kalpana Gupta, now assistant professor of medicine at Yale University, was principal investigator of the study. Her co-authors include the UW's Walter Stamm, professor of medicine and head of the Division of Allergy and Infectious Disease, and Ann Stapleton, associate professor of medicine in the Division of Allergy and Infectious Disease.