Painful kidney stones are responsible for about half a million visits to emergency rooms each year, according to the National Kidney and Urologic Diseases Information Clearinghouse. The most common types of kidney stones are made of calcium crystals, which can become lodged in the kidneys or tubes that carry urine. Interestingly, drinking lemon juice is a natural way to prevent some types of kidney stones.
How Calcium Kidney Stones Form
Calcium kidney stones also contain one of two other substances: oxalate or phosphate. The most common type of kidney stones is made of calcium oxalate. Calcium, oxalate, and phosphate are normally dissolved in the urine. However, when the concentration of these substances rises above a certain threshold, tiny crystals begin to form. If the concentration remains high, the crystals may begin to stick together, forming larger and larger stones. Lemon juice is effective in preventing calcium stones, especially stones made of calcium oxalate.
Mechanism
Lemon juice aids in the prevention of calcium oxalate stones by increasing the amount of citrate in the urine. Citrate, along with magnesium and pyrophosphate, are chemicals naturally present in the urine that prevent formation of crystals in the urine. In addition to elevated levels of calcium and oxalate in the urine as a cause of kidney stones, low levels of citrate may also trigger the development of these stones. Lemon juice is a natural source of citrate, and drinking this juice regularly increases the level of citrate in the urine.
Quantity
The University of Maryland Medical Center recommends drinking 0.5 cup of lemon juice each day to prevent calcium oxalate kidney stones. Because lemon juice is very sour, you may prefer drinking lemonade, which combines lemon juice, water and sugar. However, make sure you choose lemonade made from real lemon juice, as those made from powders are not good sources of citrate. Drinking eight cups of lemonade is required to consume 0.5 cup of lemon juice.
Considerations
Although orange and lemon juices are similar in that they are both made from citrus fruits and contain citrate, orange juice is not recommended to prevent calcium oxalate kidney stones. Although orange juice does effectively raise citrate levels in the urine, it also raises oxalate levels. Additionally, if you choose to drink lemonade as a source of lemon juice, note that total amount of sugar in eight glasses of this beverage may be quite high. If you are watching your weight and/or calorie intake, you may want to sweeten this juice with a no-calorie sugar substitute instead of real sugar.
