ABSTRACT

Calcium oxalate stones are the most common type of kidney stone, and dietary oxalate is a key modifiable risk factor for recurrence. We aimed to investigate the effect of a low-oxalate diet compared to a standard diet on the rate of recurrent kidney stones in individuals with a history of calcium oxalate stones. We conducted a single-blind, randomized controlled trial enrolling 200 adults with a history of calcium oxalate kidney stones confirmed by urinalysis or imaging. Participants were randomly assigned to either a low-oxalate diet group (n=100) or a standard diet group (n=100). The low-oxalate diet contained approximately 40mg of oxalate per day, achieved through education and personalized meal plans, while the standard diet reflected typical food choices without specific oxalate restriction. Primary outcome was the incidence of recurrent stone formation diagnosed by urinalysis or imaging during a one-year follow-up period. Secondary outcomes included changes in urinary oxalate excretion, dietary oxalate intake, and quality of life (QoL) measured using the SF-36 questionnaire.  The incidence of recurrent kidney stones was significantly lower in the low-oxalate diet group compared to the standard diet group (12% vs. 24%, p=0.02). Urinary oxalate excretion decreased significantly in the low-oxalate group compared to the standard group (35mg/24h vs. 50mg/24h, p<0.001). Dietary oxalate intake as assessed by food diaries also decreased significantly in the low-oxalate group (50mg/day vs. 120mg/day, p<0.001). No significant differences in QoL scores were observed between the groups at baseline or follow-up. A low-oxalate diet significantly reduces the risk of recurrent calcium oxalate kidney stones compared to a standard diet. This dietary strategy represents a safe and effective intervention for individuals with a history of this common condition.

Keywords

Kidney stones, calcium oxalate, oxalate diet, recurrence, randomized controlled trial.

MJE-009