The question

Cranberry juice has long been thought to be a solid home remedy for preventing urinary tract infections. Put to the test, does the belief hold up?

This study

The study involved 185 elderly women (average age 86) living in nursing homes, a population the researchers considered prone to urinary tract infections. They were randomly assigned to take two cranberry capsules (with an active ingredient equivalent to 20 ounces of cranberry juice) or placebo capsules daily. Over the next year, periodic urinalysis revealed the presence of bacteria and white blood cells indicative of a urinary tract infection in 29 percent of both groups. In addition, essentially no difference was found among those who did and did not take cranberry capsules in the number of women who reported symptoms of a urinary tract infection.

Who may be affected

Women, who are four times as likely as men to get a urinary tract infection. Bacteria are the most common cause. Infection can occur anywhere along the tract that urine follows — from the kidneys through tubes called ureters to the bladder and then through the urethra, another tube, to exit the body. Symptoms can include frequent strong urges to urinate, a burning feeling when urinating, urine that is cloudy or bloody and possibly strong-smelling, back or pelvic pain and lower abdominal pressure or bloating. Each year, more than 8 million people in the United States see a doctor because of a urinary tract infection.


Whether the findings would apply to men was not tested. The supplements and placebo used in the study were provided by Pharmatoka, which produces herbal health products.

Find this study

Online Oct. 27 in JAMA (jama.com; click on “New Online”).

Learn more

Information on urinary tract infections is available at umm.edu/health (search for “UTI”). More on cranberries can be found at nccih.nih.gov (search for “cranberry”).

The research described in Quick Study comes from credible, peer-reviewed journals.