Several small studies have investigated the effect of soda on urinary composition in healthy volunteers
with inconsistent results (11–14). Relatively small cross-sectional (5) and case-control (6) studies as well as a randomized controlled study (7) suggested anassociationbetweensodaandhistory(5,6)orrecurrence (7) of kidney stones without further exploring the specific beverage (e.g., cola or sugar-sweetened sodas versus artificially sweetened versions). This issue may be important, because sugar-sweetened beverages contain fructose, which has been found to be associated with kidney stones (15) as well as known risk factors for kidney stones, such as gout (16,17) and obesity (18). Also, it has been postulated that cola-containing beverages may have differential effects on urine composition and hence, lithogenic risk compared with noncolas, with the former containing the potentially lithogenic orthophosphoric acid and the latter containing citric acid, which may increase urinary citrate excretion and reduce the risk of stones (19).