The Cranberry Cure

From the WebMD Archives

Sept. 14, 2000 -- You may have heard that women suffering from urinary tract infections should drink cranberry juice. Until now, there was not much evidence to support this advice, but now a new study presented last week at a meeting of infectious disease specialists shows that the juice may just do the trick.

Women who have suffered from a urinary tract infection (UTI) are all too familiar with the frequent urge to urinate and the pain and burning that comes along with it.

Beyond being irritating, the condition has a serious side, too. Expert Gregor Reid, PhD, says that of the approximately 11 million women who suffered from a UTI in 1997, about 10% had the infection travel to their kidneys, which can have serious consequences and may require hospitalization.

According to Reid, who was not involved in the study, "Cranberry in excess can cause kidney stones, so you don't want to overdo this, but I think there is [compelling] evidence that if you take a glass of cranberry [juice a day,] it could prevent UTI. ... You can also get cranberry extract in powder form, but we haven't proved [that it works in the same way as juice]." Reid is a professor of microbiology and immunology at the University of Western Ontario and associate scientific director of the Lawson Health Research Institute in London, Ontario.

The researchers from Finland, led by Tero Kontiokari from the Finnish Student Health Services at Oulu University, recruited 150 women with persistent UTIs. Fifty drank just under two ounces of cranberry juice a day for six months. Another fifty drank a preparation of Lactobacillus, a 'friendly' bacteria that helps prevent yeast infections. The final fifty women were given no treatment.

After six months, only eight women taking cranberry juice had experienced a UTI, compared with 19 of those taking Lactobacillus, and 18 not taking anything.

It is not clear how cranberry juice prevents UTIs. The most common theory among experts is that one or more of its ingredients prevent bacteria from attaching to the urinary bladder wall, so they get washed away more easily in the urine. Others speculate that cranberry juice, a drink high in acid, makes it difficult for bacteria to grow.

Urogynecologist Marcella Roenneburg, MD, from the Gynecology Center of Mercy Medical Center in Baltimore, offers several additional ways for women to prevent urinary tract infections.

  • Drink plenty of water.
  • Urinate often.
  • Urinate before and after sex.

For her patients who suffer from persistent UTIs, she recommends a glass of cranberry juice daily as well as vitamin C tablets to acidify the urine. She says patients can take cranberry in powdered extract form or by drinking the juice. But watch out, not all cranberry juices are created equal. Cranberry cocktail, for instance, is composed mainly of other ingredients. Check labels to ensure a high proportion of actual cranberry juice in whatever preparation you choose.