Diet To Reduce Mild Hyperoxaluria In Patients With Idiopathic Calcium Oxalate Stone Formation: A Pilot Study

Main Category: Urology / Nephrology
Article Date: 26 May 2009 - 2:00 PDT

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UroToday.com - You pass what you eat! If you eat wisely, passage shouldn't be painful. This may be especially true for stone formers. To be sure, high fluid intake resulting in a urine output of > 2 liters per day is key; however, what is eaten also plays a role. In this study among 56 hyperoxaluric patients on a low oxalate diet, the institution of a low salt (4-5 grams/day), low animal protein (approximately 20 grams per day vs. a norm of 50 grams per day), and normal calcium diet over a 3 month period, resulted in a statistically significant drop in 24 hour urine calcium (364 to 263 mg/d) and oxalate (50 to 35 mg/d).

Sodium also dropped (238 to 118 mmol/d) and the patients had a 2 kilogram fall in body weight; both of these changes were likewise statistically significant. None of these changes occurred in a group of patients just instructed on a low oxalate diet.

Hypothetical explanations for the beneficial effects include: low oxalate intake, less oxalate intestinal absorption (e.g. less fat in the diet leaves more calcium to bind oxalate in the gut), and theoretically less endogenous oxalate production (e.g. due to lower intake of certain amino acids and carbohydrates).

Unfortunately, supersaturation data for calcium oxalate was not supplied; likewise, there is no long term follow-up to show that these presumed beneficial effects translated into fewer future stone episodes for these patients. These data will be necessary before this diet can be widely adopted, but in the mean time, it seems like a relatively simple and palatable way to go.

Nouvenne A, Meschi T, Guerra A, Allegri F, Prati B, Fiaccadori E, Maggiore U, Borghi L
Urology. 2009 Apr;73(4):725-30, 730.e1.
doi: 10.1016/j.urology.2008.11.006

Reported by UroToday.com Medical Editor Ralph V. Clayman, MD

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