Methods: A total of 30 BALB/c female mice (age 3 weeks) were randomized to receive 1 of 3 ad libdiets: standard mouse chow (13% fat, 25% protein, 62% carbohydrates kcals), a complex-carbohydrate-based Western diet (35% fat, 17% protein, 48% carbohydrate kcals), or a Western diet in which 95% of the carbohydrate kcals were from fructose plus 3.84g sodium/kg of diet. Body weights were measured twice weekly. Mice remained on study for 30 days, and urine was collected on Days 0 (at randomization), 1, 2, 5, 10, 15, 20, 25, and 30 by applying gentle suprapubic pressure. All samples were pooled into 3 samples per arm (Days 0-2, 5-15, and 20-30) and sent for analysis of creatinine, uric acid, urea nitrogen, calcium, potassium, sodium, magnesium, phosphorus, sulfate, citrate, and oxalate. Upon harvest at Day 30, we collected serum by cardiac puncture as well as bladder and kidneys for subsequent analyses.
Results: There were no significant differences in body weights among the 3 groups, although the mice consuming the high-fructose, high-sodium diet trended to be larger on Day 30 (p=0.15). We found no observable differences in stone-forming analytes in the urine of the 3 dietary arms. However, we did find a substantial decrease in urinary magnesium and citrate levels of Western diet groups compared to the mice consuming mouse chow.
Conclusion: Results from this study suggest that consumption of Western diets, especially those high in fructose and sodium may lead to decreases in stone-forming inhibitors magnesium and citrate. Although more research is necessary, this decrease in the inhibitors may explain, in part, how diet may play a role in pediatric stone formation.