Kidney stones: rating what you drink.

At some point in life, approximately one in eight U.S. residents develops kidney stones, often heralded by nausea and intermittent, stabbing pains in the back or groin. To limit recurrence of these mineral deposits, doctors frequently tell patients to dri nk more fluids. Now, a study indicates that what people drink can also make a big difference.

As part of an ongoing project, Meir J. Stampfer and his coworkers at the Harvard School of Public Health in Boston surveyed diet and other health factors among 45,289 male health professionals (none of them physicians). Over a 6-year period, 753 of these volunteers developed kidney stones. After accounting for known risk factors, including age, the researchers identified certain drinks that appeared to affect stone development.

On average, they report in the Feb. 1 American Journal of Epidemiology, a man's risk of developing kidney stones fell by 4 percent for each 8 ounces of water consumed daily. That same amount of liquid lowered the risk by 10 percent for coffee, 14 percent for tea, 21 percent for beer, and 39 percent for wine. For each 8-ounce glass of apple or grapefruit juice consumed daily, the risk of stone formation skyrocketed some 36 percent.

Stampfer acknowledges that the juice findings came as a surprise. And while the coffee and tea benefit may reflect caffeine's role in boosting urine output, he notes that caffeinated soft drinks offered no clear benefit over water.