Dietary Prevention of Renal Calculi: recent publications and research

Current Clinical Trials - where the new research is heading.

National Guideline Clearinghouse

High dietary magnesium intake decreases hyperoxaluria in patients with nephrolithiasis.
Eisner BH, Sheth S, Dretler SP, Herrick B, Pais VM Jr. Urology. 2012 Oct;80(4):780-3. Epub 2012 Aug 22. PMID: 22921695 Conclusion: Increasing magnesium intake was associated with decreasing hyperoxaluria in this population of patients with stone formation. Our findings showed that high magnesium intake might be required to observe clinically significant effects from magnesium. PDF

The impact of obesity on urine composition and nephrolithiasis management.
Al-Hayek S, Jackman SV, Averch TD. J Endourol. 2012 Sep 11. [Epub ahead of print] PMID: 22967041
Conclusion: OW and obese patients have different stone composition with increased excretion of stone promoters in the urine. Stone prevention measures should be introduced during metabolic syndrome evaluation.

Noncitrus alkaline fruit: a dietary alternative for the treatment of hypocitraturic stone formers.
Baia Lda C, Baxmann AC, Moreira SR, Holmes RP, Heilberg IP. J Endourol. 2012 Sep;26(9):1221-6. Epub 2012 Jun 4. PMID: 22500592
Conclusion: These findings suggested that melon, a noncitrus source of potassium, citrate, and malate, yielded an increase in urinary citrate excretion equivalent to that provided by orange, and hence represents another dietary alternative for the treatment of hypocitraturic stone-formers. Despite its low potassium content, lime also produced comparable increases in citraturia possibly because of its high citric acid content.

Recurrent Nephrolithiasis in Adults: Comparative Effectiveness of Preventive Medical Strategies [Internet].
Fink HA, Wilt TJ, Eidman KE, Garimella PS, MacDonald R, Rutks IR, Brasure M, Kane RL, Monga M. Rockville (MD): Agency for Healthcare Research and Quality (US); 2012 Jul. PMID: 22896859
Conclusion: Increased fluid intake, reduced soft drink consumption, thiazide diuretics, citrate pharmacotherapy, and allopurinol reduce risk of recurrent calcium stones. Effects of other dietary interventions appear mixed. We identified no RCTs for uric acid or cystine stones. Data regarding whether baseline or followup biochemistries predict treatment efficacy is extremely limited. PDF

Impact of nutritional factors on incident kidney stone formation: a report from the WHI OS.
Sorensen MD, Kahn AJ, Reiner AP, Tseng TY, Shikany JM, Wallace RB, Chi T, Wactawski-Wende J, Jackson RD, O'Sullivan MJ, Sadetsky N, Stoller ML; WHI Working Group. J Urol. 2012 May;187(5):1645-9. Epub 2012 Mar 14. PMID: 22425103
Conclusion: This study adds to the growing evidence underscoring the importance of maintaining adequate fluid and dietary calcium intake. Greater dietary calcium intake significantly decreased the risk of incident kidney stones. In contrast, excess sodium intake increased the risk of incident nephrolithiasis, especially in women with the highest intake. Animal protein intake was not independently associated with nephrolithiasis. PDF

Treatment and prevention of kidney stones: an update.
Frassetto L, Kohlstadt I. Am Fam Physician. 2011 Dec 1;84(11):1234-42. PMID: 22150656 Conclusion: For prevention of calcium oxalate, cystine, and uric acid stones, urine should be alkalinized by eating a diet high in fruits and vegetables, taking supplemental or prescription citrate, or drinking alkaline mineral waters. For prevention of calcium phosphate and struvite stones, urine should be acidified; cranberry juice or betaine can lower urine pH. PDF

Demystifying the medical management of nephrolithiasis.
Lipkin ME, Preminger GM. Rev Urol. 2011;13(1):34-8. PMID: 21826126 [PubMed]. Duke Comprehensive Kidney Stone Center, Durham, NC
Abstract: Nephrolithiasis is a common problem associated with significant costs to the health care system. Its prevalence continues to increase, particularly in women, which is attributed to changes in diet and lifestyle. The costs associated with the evaluation and management of nephrolithiasis in the United States has been estimated to be $1.83 billion, and, without any intervention, the risk of recurrence is high. This article reviews the management options for nephrolithiasis including a new formulation of potassium citrate, Urocit®-K 15 mEq, that allows for dosing flexibility which can lead to improved compliance and tolerability. PDF

Ambient temperature as a contributor to kidney stone formation: implications of global warming.
Fakheri RJ, Goldfarb DS. Kidney Int. 2011 Jun;79(11):1178-85. Epub 2011 Mar 30. Review. PMID: 21451456 
Abstract: Nephrolithiasis is a common disease across the world that is becoming more prevalent. Although the underlying cause for most stones is not known, a body of literature suggests a role of heat and climate as significant risk factors for lithogenesis. Recently, estimates from computer models predicted up to a 10% increase in the prevalence rate in the next half century secondary to the effects of global warming, with a coinciding 25% increase in health-care expenditures.

Evaluation and medical management of the kidney stone patient.
Paterson R, Fernandez A, Razvi H, Sutton R. Can Urol Assoc J. 2010 Dec;4(6):375-9. No abstract available. PMID: 21191493 [PubMed - in process]
Dietary Counselling Statement

All calcium stone formers should be counselled on dietary interventions to reduce stone recurrence or progression. Dietary recommendations include (Level 1–3 Evidence, Grade A–C recommendation):

• Increased fluid intake with a goal urine output of >2 litres per day
• Reduced salt ingestion (<2300 mg sodium daily)
• Reduced animal protein intake (no more than 2 meals daily with less than 6 to 8 ounces per day)
• Moderate calcium intake (1000 to 1200 mg/day)
• Moderate consumption of high-oxalate content foods (spinach, strawberries, nuts, rhubarb, wheat germ, dark chocolate, cocoa, brewed tea) with limited vitamin C intake to <1000 mg daily
• Increased intake of citrate-rich fluids (lemonade, orange juice) PDF

Diet, fluid, or supplements for secondary prevention of nephrolithiasis: a systematic review and meta-analysis of randomized trials.
Fink HA, Akornor JW, Garimella PS, MacDonald R, Cutting A, Rutks IR, Monga M, Wilt TJ. Eur Urol. 2009 Jul;56(1):72-80. Epub 2009 Mar 13. Review. PMID: 19321253 [PubMed - indexed for MEDLINE]
Conclusion: High fluid intake decreased risk of recurrent nephrolithiasis. Reduced soft drink intake lowered risk in patients with high baseline consumption. Data for other dietary interventions were inconclusive, although limited data suggest possible benefit from dietary calcium. PDF

Calcium supplementation and incident kidney stone risk: a systematic review.
Heaney RP. J Am Coll Nutr. 2008 Oct;27(5):519-27. Review. PMID: 18845701 [PubMed - indexed for MEDLINE]
Conclusion: Stone risk in postmenopausal women has increased substantially in the past 40 years, but absolute population incidence estimates vary widely from a low of about 70 incidents/100,000/yr for Olmsted County, MN, today, to a concurrent high of approximately 190/100,000/yr for the Nurses' Health Study II. Reported WHI incidence rates are higher still, with values around 300/100,000/yr for various WHI subgroupings. The reasons for these discordances are unclear. Despite this uncertainty about background rate, most of the studies show no increase in stone risk with high calcium intake (from either diet or supplements). Contrariwise there is a substantial body of evidence, both from controlled trials and from observational studies, indicating that there is an inverse relationship between calcium intake and stone risk. PDF

Kidney Stone type	Population	Circumstances	Details
Calcium oxalate	80%	when urine is acidic (low pH)	Some of the oxalate in urine is produced by the body. Calcium and oxalate in the diet play a part but are not the only factors that affect the formation of calcium oxalate stones. Dietary oxalate is an organic molecule found in many vegetables, fruits, and nuts. Calcium from bone may also play a role in kidney stone formation.
Calcium phosphate	___%	when urine is alkaline (high pH)
Uric acid	5-10%	when urine is persistently acidic	Diets rich in animal proteins and purines: substances found naturally in all food but especially in organ meats, fish, and shellfish.
Struvite	10-15%	infections in the kidney	Preventing struvite stones depends on staying infection-free. Diet has not been shown to affect struvite stone formation.
Cystine	___%	rare genetic disorder	Cystine, an amino acid (one of the building blocks of protein), leaks through the kidneys and into the urine to form crystals.

Reilly Jr. RF, Chapter 13: Nephrolithiasis, pp. 192–207 in Reilly Jr. and Perazella (2005)