Impact of Calcium–Magnesium Ratio in Purified Water Remineralization on Calcium Oxalate Crystal Formation and Renal Injury

Despite the known association between calcium and magnesium in drinking water and stone risk, the difference in stone prevention of purified water remineralized with varying calcium-to-magnesium ratios (Ca:Mg) remains unclear. Objectives: This study investigates the impact of different Ca:Mg in the remineralization of purified water on calcium oxalate crystallization and renal injury. Methods: Sixty male Sprague-Dawley rats were induced calcium oxalate crystals by a sodium oxalate diet and divided into six groups, where they drank purified water with or without remineralized varying Ca:Mg (0.5, 3.4, 10, 20, 100). Serum and urine biomarkers of renal function, renal injury, mineral metabolism, bone metabolism, and urine calcium oxalate crystals were detected. Kidneys were isolated for pathological examination. Results: Findings showed that remineralization by 0.5 and 3.4 Ca:Mg significantly reduced urinary calcium oxalate crystallization, renal injury, and improved renal function, while extreme ratios (Ca:Mg over 10) showed no benefits. Conclusions: These results elucidate the pathophysiological effects of Ca:Mg in drinking water on renal health, particularly emphasizing the protective role of the 0.5 and 3.4 in inhibiting calcium oxalate crystallization and mitigating renal injury. It provides a quantifiable reference for purified water remineralization aimed at stone prevention.