Fizzy citrus ones such as 7UP, Sunkist and Sprite contain lots of citrate which inhibits the formation of calcium oxalate stones -- the most common form of the complaint. Stones grow when there are more crystal-forming substances such as calcium in urine than can be diluted by available fluid.

U.S. urologist Dr Brian Eisner, who led the study, said, "Drinking these sodas may be a good thing."  

From the May 24, 2010, Prepared Foods E-dition