February 16, 2015
World Journal of Urology
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Urinary stone disease is a common indication for urologic evaluation and results in considerable morbidity to the patient and cost to the healthcare system. There is strong evidence supporting the relationship between various dietary factors and urine composition, and dietary modification serves as an opportunity to reduce risk among patients at risk for recurrent stone formation.
The authors of this comprehensive review summarize the role of dietary factors in the development of urinary stone disease, and offer the reader practical suggestions surrounding dietary changes that may ultimately improve stone risk. The data reported in this review can, and should, be used to counsel patients regarding dietary means to improve urinary parameters thereby reducing risk for recurrent stone formation.
– Matthew J. Resnick, MD
Abstract
Dietary factors have been shown to influence urine composition and modulate the risk of kidney stone disease. With the rising prevalence of stone disease in many industrialized nations, dietary modification as therapy to improve lithogenic risk factors and prevent stone recurrence has gained appeal, as it is both relatively inexpensive and safe. While some dietary measures, such as a high fluid intake, have been shown in long-term randomized clinical trials to have durable effectiveness, other dietary factors have been subjected to only short-term clinical or metabolic studies and their efficacy has been inferred. Herein, we review the current literature regarding the role of diet in stone formation, focusing on both the effect on urinary stone risk factors and the effect on stone recurrence.
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Calcium: Strict dietary calcium restriction is no longer advised for stone formers with or without hypercalciuria. At present, stone formers are advised to consume the recommended daily allowance (RDA) of calcium (1,000–
1,200 mg, or approximately 3 servings of dairy daily), although exceeding this intake is discouraged.
Vitamin D: Currently, repletion of vitamin D to normal serum levels is considered safe, although monitoring of urinary calcium levels in patients with hypercalciuria may be advisable.
Effect of Acid Load/High Protein: However, the results of randomized clinical trials assessing the effect of animal protein on actual stone formation have been conflicting, perhaps in part because the independent risk of animal protein intake, apart from other dietary factors, has not been studied.
Omega-3 Fatty Acids: 1,200 mg/day. Helps some, doesn’t help others. Worth a try.
Sodium: a low-salt diet could reduce calcium excretion in hypercalciuric stone formers and is now recommended for patients found to have high sodium excretion on 24-h urine samples.
Oxalate: At present the efficacy of dietary oxalate restriction for the prevention of stone recurrence is assumed, but unproven.
Water: High fluid intake has been shown in a randomized trial to increase urine volume and reduce the risk of recurrent stone formation.
Soda: A randomized trial found that soft drinks increase the risk of recurrent stone formation, while epidemiologic studies have linked coffee and tea with reduced risk of incident stone formation.