Beverage use and risk for kidney stones in women

Background: An increase in fluid intake is routinely recommended for patients who have had kidney stones to decrease the likelihood of recurrence. However, data on the effect of particular beverages on stone formation in women are limited. Objective: To examine the association between the intake of 17 beverages and risk for kidney stones in women. Design: Prospective cohort study with 8 years of follow-up. Setting: United States. Participants: 81093 women in the Nurses' Health Study who were 40 to 65 years of age in 1986 and had no history of kidney stones. Measurements: Beverage use and diet were assessed in 1986 and 1990 with a validated, self-administered food-frequency questionnaire. The main outcome measure was incident symptomatic kidney stones. Results: During 553081 person-years of follow-up over an 8-year period, 719 cases of kidney stones were documented. After risk factors other than fluid intake were controlled for, the relative risk for stone formation for women in the highest quintile of total fluid intake compared with women in the lowest quintile was 0.62 (95% CI, 0.48 to 0.80). Inclusion of consumption of specific beverages in the multivariate model significantly added to prediction of risk for kidney stones (P < 0.001). In a multivariate model that adjusted simultaneously for the 17 beverages and other possible risk factors, risk for stone formation decreased by the following amount for each 240-mL (8-oz) serving consumed daily: 10% (CI, 5% to 15%) for caffeinated coffee, 9% (CI, 2% to 15%) for decaffeinated coffee, 8% (CI, 1% to 15%) for tea, and 59% (CI, 32% to 75%) for wine. In contrast, a 44% (CI, 9% to 92%) increase in risk was seen for each 240-mL serving of grapefruit juice consumed daily. Conclusions: An increase in total fluid intake can reduce risk for kidney stones, and the choice of beverage may be meaningful.