Red wine and kidney stone risk in men:
45,289 men without previous renal stones were followed in the Health Professionals Follow-up Study for formation of stones. Increasing intake of fluid reduced kidney stone formation. Specific types of beverages were found to decrease risk of stone formation. For each 8 ounce serving daily of the following beverages consumed per day, stone formation risk decreased by the following amounts on average: coffee with or without caffeine, 10%; tea, 14%; beer, 21%; and wine, 39%. Also, for each 8 ounce serving of apple juice, stone formation risk increased by 35%, and grapefruit juice increased risk by 37%. (7)