Lemonade could prevent kidney stones

In 2006 American Urological Association annual meeting in Atlanta, two research groups reported that drinking lemonade could help prevent kidney stones.
Kidney stones is one of the most painful of the urologic disorders. According to the U.S. National Institutes of Health, 1 person in 10 develops kidney stones during their lifetime and renal stone disease accounts for 7-10 of every 1000 hospital admissions.
Kidney stones form when there is a high level of calcium, oxalate, or uric acid in the urine; a lack of citrate in the urine; or insufficient water in the kidneys to dissolve waste products. The kidneys must maintain an adequate amount of water in the body to remove waste products. If dehydration occurs, high levels of substances that do not dissolve completely (e.g., calcium, oxalate, uric acid) may form crystals that slowly build up into kidney stones.
Urine normally contains chemicals-citrate, magnesium, pyrophosphate-that prevent the formation of crystals. Low levels of these inhibitors can contribute to the formation of kidney stones. Of these, citrate is thought to be the most important. Lemons are rich in citrate. Clinical research demonstrated that the regular consumption of the refreshing drink- or even lemon juice mixed with water increased the production of urinary citrate. That is why drinking lemonade could help prevent kidney stones.
Simple idea, easy logic. Why didn't I have this idea before ?