In a study reported in the March 9, 1994 issue of the Journal of the American Medical Association, regular consumption of cranberry juice reduced the frequency of bacteria and white blood cells, the body's response to infection, in the urine of 153 older women. Median age of the volunteers was 78.5 years.

Although anecdotal evidence from the 1920s to the 1970s suggested that the acidification of the urine by cranberry juice was effective in treating cystitis, an inflammation of the urinary baladder, the JAMA study was the first placebo-controlled, large-scale clinical trial to address the issue, according to Jerry Avorn, M.D., of the Harvard Medical School, the principal investigator.

In an earlier study, published in The New England Journal of Medicine in May 1991, the researchers suggest there is a compound in cranberry and blueberry juices which may prevent E. coli, the most common cause of urinary tract infections, from adhering to the lining of the bladder.

During the Harvard study, the women who drank 10 ounces of cranberry juice daily for six months were 58 percent less likely to have bacteriuria (bacteria in the urine) and pyuria (white blood cells, causing pus in the urine) than the women who were given a placebo drink.

A urinary tract infection (UTI) includes a variety of conditions, such as cystitis. These infections are said to add over $ 1 billion to our annual health-care bill.

Because of their anatomy, women are 10 times more likely to have a UTI than men. About 25 to 35 percent of women between the ages of 20 and 40 have had at least one UTI.

In women, a UTI generally develops when bacteria from the rectal area colonize in the nearby vagina, enter the urethra, and penetrate the bladder, causing an infection. Symptoms include pain during urination and frequency and urgency of urination. If the infection reaches the kidneys, it can cause fever, chills, flank pain and the justnamed complications.

Men are less susceptible to UTIs because the opening of the urethra at the end of the penis is a considerable distance from the rectal area, the source of the bacteria. In addition, the opening of the urethra is surrounded by dry epidermal cells, rather than the moist mucosal cells women have in the vagina.

Causes of cystitis include poor hygiene, vigorous intercourse and infrequent urination. Wiping from back to front after a bowel movement spreads bacteria. Also implicated are feminine hygiene sprays, douches and bubble baths. To prevent an infection, also avoid wearing tight clothing and wear cotton underwear. Women who hold urine unnecessarily are also at risk in developing UTIs.