Diet to reduce mild hyperoxaluria in patients with idiopathic oxalate stone formation: a pilot study

OBJECTIVES To assess whether a normal-calcium, low-animal protein, low-salt diet is effective in reducing hyperoxaluria in idiopathic calcium oxalate nephrolithiasis compared with a traditional lowoxalate diet, routinely recommended by clinicians. METHODS We treated 56 patients with idiopathic calcium oxalate stone formation who presented with mild hyperoxaluria (40 mg/d) while consuming a free diet with a normal-calcium, low-animal protein, low-salt diet for a 3-month period. We compared the results obtained with this diet with those of a historical control group of 20 hyperoxaluric patients treated in the traditional way with a low-oxalate diet. RESULTS After 3 months of therapy, the mean oxaluria level had decreased from 50.2 to 35.5 mg/d with the normal-calcium, low-animal protein, low-salt diet and from 45.9 to 40.2 mg/d with the traditional diet (adjusted difference between post-treatment mean value 7.3 mg/d, 95% confidence interval 12.3 to 2.2, P .005). CONCLUSIONS The results suggest that a normal-calcium, low-animal protein, low-salt diet can reduce oxalate excretion in hyperoxaluric patients. This should encourage the undertaking of a randomizedcontrol study to confer more solid evidence in support of our findings.