The new research shows that drinking lemonade could help prevent painful kidney stones. Regular consumption of lemon juice mixed with water may increase the production of urinary citrate, a chemical in the urine that prevents the formation of crystals that may build up into kidney stones.

In the study led by Kristina Penniston, an assistant scientist in the Department of Surgery at the University of Wisconsin School of Medicine and Public Health, researchers retrospectively examined the medical records of 100 patients who had been prescribed lemonade therapy after seeking treatment for calcium oxalate kidney stones. Calcium oxalate stones are the most common type of kidney stones.

About two thirds of the patients drank about 4 ounces of pure lemon juice that they poured into 2.5 liters of beverages throughout the day or 32 ounces of low-sugar or low-calorie prepared lemonade. The remaining patients in the study were treated with a combination of lemonade therapy and potassium citrate, a medication that maintains the antacid level in urine.

After an average treatment time of about 40 months, in both groups, urinary citrate increased and so did urine volume. But the increase in volume was only significant in groups with lemonade therapy. For patients prone to kidney stones, drinking lots of fluids and increasing urinary volume may help prevent future stone formation.

In another study presented at the conference, conducted by researchers at Duke University, 12 patients with mild-to-moderate hypocitrauria -- a condition that causes a person to produce low levels of urinary citrate -- drank 120 milliliters of lemon juice mixed with two liters of water throughout the day.

After the researchers compared the people treated with lemonade therapy to patients taking potassium citrate, results showed that 11 of the 12 patients had increased urinary citrate levels during lemonade therapy.