Among the most commonly consumed citrus fruits, lemons contain the greatest concentrations of citric acid (49,2 g/Kg), nearly 5 times the concentrations in the orange. A half cup of pure lemon juice can provide a daily amount of citrate comparable to that of a standard daily dose of alkali citrate medications. The citrate supplied with the juice that escapes metabolic degradation in vivo is excreted unchanged in the urine where may prevent the tendency of calcium oxalate salts to precipitate. Lemon juice supplementation may also have the additional advantage of reducing urinary calcium excretion without affecting oxalate excretion, while orange juice does not affect urinary calcium and may increase urinary oxalate.