Folk therapy for vaginitis looking good.

For years, mothers have advised their daughters to eat yogurt to cure or prevent recurrent vaginal yeast infections. But gynecologists have remained divided over the efficacy of the treatment.

Now, the first controlled study using yogurt to fight yeast infections shows that eating an 8-ounce carton of the dairy food every day can relieve chronic vaginal yeast infections. However, the yogurt must contain live cultures of the bacterium Lactobacilllus acidophilus, the study found.

Gynecologist Eileen Hilton and her colleagues at the Long Island Jewish Medical Center in New Hyde Park, N.Y., tested the benefits of eating yogurt among 13 women with a history of vaginal yeast infections. The women ate yogurt daily for six months, then abstained from yogurt for the following six months.

During the time that they ate yogurt, the women proved less likely to develop a yeast infection, Hilton's group reports in the March 1 Annals of Internal Medicine. Moreover, women protected from yeast infections by the therapy had higher levels of L. acidophilus in their rectums or vaginas. The authors attribute the yogurt's effects to movement of the bacteria from the rectal area into the vagina.

"It appears that the gastrointestinal strain of L. acidophilus colonized the vaginal tract of our patients," Hilton and her colleagues write. These benign bacteria are more resistant to digestive acids than other gut microbes. Once in the vagina, the researchers suggest, the bacteria may out-compete yeast for growth nutrients, preventing infection.

In an editorial accompanying the article, physician David J. Drutz of St. Michael's Medical Center in Newark, N.J., comments that the study "represents a needed first step" in demonstrating the effectiveness of L. acidophilus. However, he warns women against seeking a therapy for their yeast infections from the grocery shelves. Most commercial brands of yogurt do not contain L. acidophilus, and many are pasteurized, which would kill the bacterium. He adds that several research groups are now investigating whether direct application of L. acidophilus to the vagina--using either yogurt or suppositories containing the bacterium--may provide the best route of administration.