Dietetic and lifestyle recommendations for stone formers

Nutrition is tightly associated with the risk of stone events. A part from genetic predisposition, a correct and balanced diet might prevent incident kidney stones. Several studies analyzed each dietary component and different diets to better understand their impact on stone recurrence. Fluids: High fluids intake is the most important factor for preventing kidney stones disease and for every 200 mL of water, the risk of stones is reduced by 13%. Soft drinks seems to be associated to a greater risk of stone events, whereas caffeine and citrus fruits juice are not. Calcium: Normally calcium intake with diet does not exceed 1.2 g/day. A balanced consumption of dairy products is capable of reducing oxalate intestinal absorption and urinary excretion compared to low calcium diet, being protective for stone disease. Oxalate: The exact amount of oxalate contained in different foods is difficult to estimate for its variability, even in the same aliment. In addition, the amount of oxalate consumed was shown to be only a minor risk factor for stone disease, whereas its intestinal absorption is strongly influenced by external factors, such as calcium intake. Dietary oxalate restriction is advisable only in patients with known elevated consumption. Sodium: High sodium intake is both associated with hypertension, heart disease and stone risk. Increased sodium consumption is directly associated to hypercalciuria in both calcium stone formers and healthy subjects. Although dietary sodium restriction to recommended values is always desirable in stone formers, it is difficult to achieve for its broad use in food preparation. Proteins: Animal proteins are associated to increased risk for stone formation, whereas vegetable and dairy proteins are not. Increased meat intake was associated to acidic urine pH, negative calcium balance and reduced anti-lithogenic urinary solutes excretion.Fruits and vegetables: Alkalizing foods are one of the most important factors for stone protection. Their consumption increases anti-lithogenic solutes as citrate, potassium and magnesium. A diet rich in fruits and vegetables is strongly recommended for stone formers. Uric acid: Elevated meat consumption is either associated to increased purine metabolism and acid load, favoring uric acid nephrolithiasis by reducing urine pH and increasing urinary excretion of uric acid, especially in patients affected by metabolic syndrome and diabetes.In conclusion, the most effective diet for stone protection is rich in fruits and vegetables, low in animal proteins and salt, with balanced dairy product consumption and obviously, with elevated fluid intake. These characteristics make vegetarian and Mediterranean diets protective and useful for stone formers, whereas western diet is at risk for stone formation.