Discussion
It is well known that higher fluid intake reduces the risk of incident (8,9) and recurrent (2) kidney stones. Our study found that the relation between fluid intake and kidney stones depends on the type of beverage consumed. Higher consumption of sugar-sweetened soda was associated with a higher incidence of kidney stones, which may be because of the fructose content. Fructose has been shown to increase the urinary excretion of calcium (23), oxalate (23), and uric acid (24), thus increasing the risk of stones (15).