Kidney stones are one of the most common disorders that affect the kidneys. Kidney stones are usually composed of calcium oxalate and/or phosphate. Less common are stones formed of uric acid, which are frequently associated with gout.
To help prevent the formation of kidney stones, physicians have traditionally recommended reducing dietary calcium intake. The true chemistry behind the formation of calcium oxalate stones shows the real enemy are the oxalates that bind with the calcium. Since calcium is a necessary nutrient, it only makes sense to reduce the intake of oxalate instead. A low oxalate diet can be rather restrictive, and since oxalates are also found in many nutritious foods, the trick here is to avoid eating foods high in oxalates in combination with calcium rich foods. For example, spinach and cheese together on a pizza may be tasty, but it's not a good combination if you are prone to kidney stones. For a list of foods high in oxalates, click here.
To reduce your intake of phosphate, simply limit your intake of sodas. Any carbonated beverage, including flavored "fizzy" waters contain phosphorous, and they generally have no other nutritional value. Eliminating them altogether would not cause any nutritional deficiencies.
Uric acid stones can be prevented by restricting purine in the diet. Foods high in purine include pork, red meat, organ meats, sardines, anchovies, and alcohol; primarily beer. If you are following a diet for the treatment of gout, you are already on the right path to preventing uric acid stones.
Increasing fluid intake, mainly water, will dilute the urine and can help in preventing the formation of kidney stones.