BACKGROUND: Patients with nephrolithiasis and hyperoxaluria generally are advised to follow a low-oxalate diet.
However, most people do not eat isolated nutrients, but meals consisting of a variety of foods with complex combinations of nutrients. A more rational approach to nephrolithiasis prevention would be to base dietary advice on the cumulative effects of foods and different dietary patterns rather than single nutrients.
STUDY DESIGN: Randomized controlled trial.
SETTING & PARTICIPANTS: Recurrent stone formers with hyperoxaluria (urine oxalate > 40 mg/d).
INTERVENTION: The intervention group was asked to follow a calorie-controlled Dietary Approaches to Stop Hypertension (DASH)-style diet (a diet high in fruit, vegetables, whole grains, and low-fat dairy products and low in saturated fat, total fat, cholesterol, refined grains, sweets, and meat), whereas the control group was prescribed a low-oxalate diet. Study length was 8 weeks.
OUTCOMES: Primary: change in urinary calcium oxalate supersaturation.
SECONDARY: Changes in 24-hour urinary composition.
RESULTS: 57 participants were randomly assigned (DASH group, 29; low-oxalate group, 28). 41 participants completed the trial (DASH group, 21; low-oxalate group, 20). As-treated analysis showed a trend for urinary oxalate excretion to increase in the DASH versus the low-oxalate group (point estimate of difference, 9.0mg/d; 95% CI, -1.1 to 19.1mg/d; P=0.08). However, there was a trend for calcium oxalate supersaturation to decrease in the DASH versus the low-oxalate group (point estimate of difference, -1.24; 95% CI, -2.80 to 0.32; P=0.08) in association with an increase in magnesium and citrate excretion and urine pH in the DASH versus low-oxalate group.
LIMITATIONS: Limited sample size, as-treated analysis, nonsignificant results.
CONCLUSIONS: The DASH diet might be an effective alternative to the low-oxalate diet in reducing calcium oxalate supersaturation and should be studied more.
Written by:
Noori N, Honarkar E, Goldfarb DS, Kalantar-Zadeh K, Taheri M, Shakhssalim N, Parvin M, Basiri A. Are you the author?
Urology and Nephrology Research Center, Department of Urology, Shahid Labbafinejad Medical Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran; Nephrology Section, New York Harbor VA Healthcare System, New York, NY; Nephrology Division, New York University School of Medicine, New York, NY; Harold Simmons Center for Kidney Disease Research & Epidemiology, Division of Nephrology and Hypertension, School of Medicine, University of California, Irvine, Irvine, CA.
Reference: Am J Kidney Dis. 2014 Mar;63(3):456-63.
doi: 10.1053/j.ajkd.2013.11.022
PubMed Abstract
PMID: 24560157
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