A systematic review of analytical observational studies investigating the association between cardiovascular disease and drinking water hardness

Abstract

The aim of this study is to systematically review and critically assess analytical observational epidemiology studies investigating the association between levels of drinking water hardness and cardiovascular disease. We searched electronic databases and used standardised forms to extract data and assess study quality. Of 2,906 papers identified, 14 met the inclusion criteria (nine case control and five cohort studies). Of the nine case control studies, seven examined both drinking water magnesium and calcium and risk of death from cardiovascular disease. A pooled odds ratio showed a statistically significant inverse association between magnesium and cardiovascular mortality (OR 0.75 (95%CI 0.68, 0.82), p , 0.001). Only two studies reported a statistically significant effect for calcium. Substantial heterogeneity between studies made calculation of a summary estimate for drinking water calcium inappropriate. Of three cohort studies reviewed, two were of good quality. A weak suggestion that soft water was harmful in females and possibly associated with a slightly greater risk of sudden death was reported, but there was no association between water hardness and mortality from stroke or cardiovascular disease. This study found significant evidence of an inverse association between magnesium levels in drinking water and cardiovascular mortality following a meta-analysis of case control studies. Evidence for calcium remains unclear.

Calcium and Magnesium in Drinking Water as Risk Factors for Ischemic Heart Disease

“…Ca from food did not affect levels of total and LDL cholesterol. Results of this study are consistent with the results of many other published studies in which the inverse relationship between water hardness and cardiovascular morbidity and mortality was established [23][24][25]. Persons who consumed medium hard drinking water had a significantly higher rate of incidence of IHD compared to people of the same sex and age who consume hard drinking water.…”

Impact of Calcium and Magnesium in Groundwater and Drinking Water on the Health of Inhabitants of the Slovak Republic

“…In other cases, these essential elements are only limited in the form of recommended values, such as in the Slovak guideline for water used for human consumption [17]. There are many publications documenting increased incidence and mortality rates for cardiovascular diseases associated with a deficit of Ca and Mg in drinking water [18,19,20,21,22,23,24]. Several studies can be found that link these deficits to increased mortality from oncological diseases as well [25,26,27,28,29,30].…”

First report on the association of drinking water hardness and endothelial function in children and adolescents

“…Some studies have documented that softer water is associated with higher CVD death rates; this protective role is suggested to be because of the water Ca content [28, 29]. …”