In most cases, stone formation is due to an interaction of genetic and environmental factors. Dietary patterns such a low fluid consumption, too much salt, too much protein, too much oxalate, and not enough calcium can all increase the risk of stone formation.
A simple dietary approach that is beneficial for the majority of kidney stone patients is reviewed below
In order for stones to develop, urine needs to be supersaturated with the chemicals that compose them. This can occur either because of dehydration or because our bodies excrete excessive levels of these chemicals. Consuming an adequate amount of fluid is a simple and safe method of decreasing urinary supersaturation.
Tap water is an excellent and readily available fluid source. Other good choices include citrus juices and mineral water preparations containing citric acid, a chemical that inhibits the crystallization of stone-forming chemicals. The soft drink, Fresca, has similar properties.
Adults patients should consume enough fluid for a daily urine output of 2 to 3 liters. Drinking 8 to 10 ounces of water per hour while awake will usually allow this to occur. Another index of adequate hydration is that urine should be almost as light as water.
Consuming large amounts of animal protein produces a number of changes in the urinary environment that may promote stone formation, including lower pH, increased excretion of calcium, oxalate and uric acid, and reduced excretion of citrate. Therefore, limiting consumption of animal protein, especially red meat, is advisable. The Atkin’s diet should be avoided as it is based on high protein intake which will promote all of the aforementioned urinary changes. A daily protein intake of 1 gram per kilogram of body weight (1 kilogram = 2.2 pounds) is recommended.
High salt consumption should be avoided as it promotes a number of deleterious urinary changes for stone patients including an increase in urinary calcium and cystine excretion, and a reduction in citrate excretion. Sodium intake should be limited to 2 grams per day for adults.
The majority of kidney stones are composed of calcium, and a combination of oxalate or phosphate or both. Dietary calcium restriction was recommended for a number of years. However, there is now ample evidence that this should not be undertaken. Most adults should eat enough dairy products or other calcium containing foods which in total provides 1 to 1.2 grams of calcium per day. An effort should be made to equally distribute calcium intake throughout daily meals.
High-Oxalate Containing Foods
Calcium oxalate stone-formers should avoid eating foods containing high amounts of oxalate. Examples of such foods include spinach, parsley, rhubarb, cranberries, celery, peanuts, soy products, fiber-containing cereals, bran and chocolate.
Stone patients should avoid consuming excessive amounts of vitamin C (ascorbate/ascorbic acid). The amount of vitamin C present in the standard multi-vitamin tablet is not excessive and thus these can be taken. However, other preparations containing greater amounts of this vitamin should not be taken as this may increase urinary oxalate excretion. Calcium supplements such as Tums and Citracal may promote increased calcium excretion when consumed. Thus, one should let their urologist know if they are taking such preparations so that special urine testing can be done to determine whether continued utilization is advisable.