Snacks and urinary oxalate: Which wins, almonds or chocolate?

Urinary oxalate (UOx) excretion is a modifiable risk factor for calcium oxalate kidney stone formation, particularly in populations with malabsorptive disorders. This study evaluated the feasibility of two oxalate loading methods - using chocolate and almonds - to induce hyperoxaluria in healthy volunteers.

Seven participants underwent baseline 24-hour urine collections, followed by 100g of dark chocolate and 150g of almonds, with subsequent 24-hour UOx measurement.

Results showed no significant increase in UOx after chocolate consumption (690 [430-870] μmol/24h vs 696 (640-800) μmol/24h, P=0.9), while almond intake led to a consistent and significant UOx rise (931 [680-990] μmol/24h, P=0.01).

An oxalate loading test using almonds results in a consistent and significant increase in oxaluria, unlike chocolate, highlighting the need to inform patients with nephrolithiasis about its potential lithogenic effect. An almond loading test can be more readily standardized across different centers, given the lack of diverse commercial forms as found with chocolate.