FOR -- The secret ingredient in cranberries that is pivotal in preventing urinary tract infections (UTIs) is concentrated tannins, called proanthrocyanidins, in the juice. In a Boston study published in the Journal of the AMA, cranberry juice was found to be effective in reducing the incidence of UTIs and the need for antibiotic treatments.

This has important implications for persons with ostomies and continent diversions. Recurrent UTIs can be common in persons who catheterize frequently. They can be more evident if proper hand washing and cleaning of catheters is not done routinely. In addition, a large proportion of women over age 65 will experience at least one UTI per year.

How does this special ingredient in cranberry juice work? The tannins from cranberries prevent E-coli bacteria, the main culprit in urinary infections, from adhering to cells that line the walls of the bladder and kidneys. The bacteria thus will "wash out" before infection can develop.

Scientists in the Boston study believe that the routine addition of cranberry juice to dietary regimes in circumstances where UTIs have a high incidence would be sensible.

AGAINST -- An article from the Mayo Clinic says drinking cranberry juice to prevent recurring bladder or urinary infections is an "old folk" remedy. Does it work? Maybe--but don't count on it.

A key to preventing a bladder infection is blocking the growth of the bacteria that cause the infection. Researchers have two theories about how cranberry juice may help:
(1) By making the urine more acidic, discouraging the growth of bacteria. But scientists don't know whether a realistic amount of cranberry juice can produce enough change in urine acidity to affect bacteria.
(2) By keeping bacteria from "sticking" to the bladder wall where they multiply and cause infections. This theory was confirmed in the laboratory and in mice, but results vary in humans.

We do know that taking 500 mg of vitamin C (ascorbic acid) twice a day along with cranberry juice can increase urine acidity. Still, if you think you have a bladder infection, don't try home remedies. See your doctor. The usual treatment is antibiotics and lots of liquids.