Does water hardness have preventive effect on cardiovascular disease?

The aim of this study is to investigate the association ofcalcium and magnesium concentration of drinking water with cardiovascular disease (CVDs) in urban and rural areas of a city in Iran.This case-control study was conducted in 2012 in Khansar County in Isfahan province, Iran. We used the official data of the Provincial health center regarding the chemical analysis data of urban and rural areas including the hardness, calcisum and magnesium content of drinking water. Data of patients hospitalized for CVD in the only specialty hospital of the city was gatheresd for the years of 2010 and 2011.In 2010, the increase in the calcium hardness above 72 mg/L, the prevalence of CVDs in 1000 population decreased; in 2011 this decrease in CVDs was observed for calcium hardness of more than 75 mg/L. In 2010, the level of Mg hardness in water ranged from 23 to 57 mg/L. By increasing Mg hardness level above 31 mg/L in 2010 and above 26 mg/L in 2011, the number of CVD in 1000 people decrease.Our study suggests favorable protective effects of water hardness, mainly water magnesium content, on CVDs. Water hardness, as well as calcium and magnesium content of drinking water may have a protective role against CVDs. Further experimental studies are necessary to determine the underlying mechanisms and longitudinal studies are required to study the clinical impacts of the current findings.