The association between domestic water hardness and kidney stone disease: a prospective cohort study from the UK Biobank

Our findings suggested that magnesium levels in water can decrease kidney stone risk, but in the overall population, domestic water hardness, calcium concentration, and calcium carbonate concentration have no significant impact on the formation of kidney stones. Interestingly, hard water and its calcium concentration can promote the formation risk of kidney stones in participants > 60 years old and females, while high magnesium concentration in domestic water can reduce the risk in males, ≤ 45 years old, and those without renal failure. The protective effects of magnesium interacted with other minerals and were more obvious in the population intake of hard water and high concentrations of CaCO 3 and calcium. This study contributes to the complex understanding of environmental factors in kidney stone etiology and suggests a need for focusing on mineral-specific effects in different populations and interaction with other minerals, which hope to provide some evidence of water's role in public health and clinical management of kidney stones.