Kidney stones and beverage choice.

Most people don't think much about kidney stones unless they've had one. Those people know that, once a stone has passed, doctors routinely recommend drinking plenty of fluids. But which ones? A new study in women indicates that some fluids may help a person avoid kidney stones and some may not.

Researchers tracking the diets of more than 80,000 female nurses nationwide between 1986 and 1994 documented 719 cases of kidney stones. Analysis of the nurses' diets in the years preceding the diagnosis of a stone showed that tea decreased the risk of stones by 8 percent, coffee--regular or decaffeinated--lowered it by about 9 percent, and moderate wine intake cut the risk by at least 20 percent, says Gary C. Curhan, a nephrologist and epidemiologist at Harvard Medical School and Brigham and Women's Hospital in Boston. The researchers, who took into account factors such as age and other nutrient intake, reported the findings in the April 1 Annals of Internal Medicine.

Strangely, an 8-ounce glass of grapefruit juice daily boosted the risk of stones by 44 percent, the data showed. Of the 17 beverages studied, no other drink had such a negative impact. The reason for grapefruit's effect, which had shown up in an earlier study of men, remains unclear, Curhan said.

Milk intake lessened slightly the chance that a woman would get kidney stones, the researchers found.

The average man faces a 3 in 1,000 chance of getting a kidney stone in any given year. For women, the risk is 1 in 1,000, but it soars to 1 in 5 for those who have already had a stone. "Modifying beverage intake might make a difference," says Curhan, but only as part of a broad treatment strategy.