People who form kidney stones generally tend to have stones with the same composition each time. Prevention is the optimal treatment for recurrent stone formers. Since some dietary components contribute to stone formation, limiting intake of foods that contain these components is advised. The diet varies depending on the individual's stone composition.
Uric Acid
A common component of kidney stones is uric acid. This compound arises partly from the process of digestion of purine-containing foods. Purines are found in animal proteins, especially organ meats and small fish. The National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) recommends limiting alcoholic beverages to no more than two per day, as alcohol may also increase production of purines in the body.
Calcium
The most common type of kidney stone is formed from calcium and oxalate. A mistaken assumption is that a low-calcium diet will help prevent these stones. The NIDDK explains how calcium in the diet is actually beneficial: calcium binds to dietary oxalate in the digestive tract, and this forms a compound that is too large to enter the blood and proceed to the kidneys. The goal should be 800 mg of dietary calcium daily, which will also help prevent calcium deficiency. The Jackson Siegelbaum Gastroenterology physicians are among many practitioners who also advise restricting intake of sodium to 2300 to 3500 mg per day to help reduce the amount of calcium excreted in the urine.
Oxalate
Oxalate, on the other hand, should be limited in the diet of calcium-oxalate stone formers. Amounts of free oxalate that do not bind to calcium will end up in the urine and can contribute to stone formation. Chocolate, tea and leafy greens are among the foods the National Kidney Foundation suggests these stone formers should avoid.
Fluids
A universal recommendation for kidney stone formers is to ingest a great deal of fluid. More water taken in helps keep the urine dilute and prevents stones from forming. The National Kidney Foundation recommends 2 to 3 qt. of fluid per day. The Cleveland Clinic suggests at least half this amount should be from water. The NIDDK warns colas, citrus juices, cranberry juice, coffee and tea can contribute to the formation of some types of stones. A guideline from Jackson Siegelbaum Gastroenterology is to have a glass of water every waking hour.
Supplements
Certain supplements can increase the presence of stone-forming components in the urine. Vitamin C metabolizes to oxalate and should not be taken in amounts above 500 mg, according to the NIDDK. Vitamin D increases absorption of calcium. Patients should take neither vitamin D nor calcium supplements before consultation with a personal physician.
