The number of studies that addressed the hard water and cardiovascular health
issue grew to be too large for the main page, so I moved them here and
will add references as I find them:
Potential Health Impacts of Hard Water, Pallav Sengupta, Int J Prev Med. Aug 2013; 4(8): 866–875,
Conclusions - Although, there is some evidence from epidemiological studies for a protective effect of magnesium or hardness on cardiovascular mortality, the evidence is being debated and does not prove causality.
Relationship between Tap Water Hardness, Magnesium, and Calcium
Concentration and Mortality due to Ischemic Heart Disease or Stroke in the
Netherlands, Lina J. Leurs, et. al., Environ Health Perspect. Mar 2010; 118(3):
414–420, Conclusions - We found no evidence for an overall significant association between tap water hardness, magnesium or calcium concentrations, and IHD mortality or stroke mortality.
Cardiovascular Health: Hard Data for Hard Water,
Adrian Burton, Environ Health Perspect. Mar 2008; 116(3), The idea that hard
water—particularly that with higher magnesium concentrations—helps ward off
cardiovascular problems has been around for 50 years. However, due to the
ecologic nature of most studies, uncontrolled confounding factors, and the
different variables and outcomes measured, no firm conclusions have ever
been drawn. The WHO is therefore coordinating worldwide efforts to compare
cardiovascular morbidity before and after changes in the calcium/magnesium
content of water supplies.
A systematic review of analytical observational studies
investigating the association between cardiovascular disease and drinking
water hardness, Catling LA, et. al., J Water
Health. 2008 Dec;6(4):433-42, Mixed results from various studies reported.
Hard drinking water does not protect against cardiovascular disease: new evidence from the British Regional Heart Study, Morris RW, et. al.
Eur J Cardiovasc Prev Rehabil. 2008 Apr;15(2):185-9, Eur J Cardiovasc Prev Rehabil. 2008 Apr;15(2):185-9,
Conclusion - This study suggests that neither high water hardness, nor high calcium or magnesium intake appreciably protect against CHD or CVD. Initiatives to add calcium and magnesium to desalinated water cannot be justified by these findings.
epidemiological studies on drinking water hardness and cardiovascular diseases, Monarca S, et. al., Eur J Cardiovasc Prev Rehabil. 2006 Aug;13(4):495-506,
Conclusion - Information from epidemiological and other studies supports the hypothesis that a low intake of magnesium may increase the risk of dying from, and possibly developing, cardiovascular disease or stroke. Thus, not removing magnesium from drinking water, or in certain situations increasing the magnesium intake from water, may be beneficial, especially for populations with an insufficient dietary intake of the mineral.
Daily intake of magnesium and calcium from drinking water in relation to myocardial infarction, Rosenlund M, et. al., Epidemiology. 2005 Jul;16(4):570-6,
Conclusion - This study does not support previous reports of a protective
effect on myocardial infarction associated with consumption of drinking
water with higher levels of hardness, magnesium, or calcium.
Spatial Analysis of the Relationship between Mortality from Cardiovascular
and Cerebrovascular Disease and Drinking Water Hardness, Juan Ferrándiz, et. al., Environ Health Perspect. Jun 2004; 112(9): 1037–1044,
Results - Our results suggest the possibility of protectiveness but
cannot be claimed as conclusive. The weak effects of these covariates make
it difficult to separate them from the influence of socioeconomic and
Health significance of drinking water calcium and magnesium, František Kožíšek,
2003, The present
contribution summarizes the existing knowledge of health significance of drinking water Ca
and Mg and the attempts to reflect it in regulation and suggests how to bridge the regulatory
gaps in this field.
The influence of calcium and magnesium in drinking water and diet on
cardiovascular risk factors in individuals living in hard and soft water
areas with differences in cardiovascular mortality, Christina Nerbrand, et. al., BMC Public Health. 2003; 3: 21,
The abstract states, From these results it is not possible to conclude any definite causal relation and further research is needed.
Drinking water and cardiovascular disease, Sauvant MP & Pepin D., Food Chem Toxicol. 2002 Oct;40(10):1311-25,
The abstract states, A link between cardiovascular disease (CVD) mortality and the hardness of drinking water (DW) is suggested by about 30 epidemiological studies performed worldwide in the general population since 1957. This review examines the main ecological studies, case-control studies and cohort studies, published between 1960 and 2000.
... To date, it would be impossible to understand this environmental findings without large intervention studies performed in well-controlled public health programs.
Calcium and magnesium in drinking water and risk of death from
cerebrovascular disease, Yang CY, Stroke. 1998
Conclusion - The results of the present study show that there is a
significant protective effect of magnesium intake from drinking water on the
risk of cerebrovascular disease. This is an important finding for the Taiwan
water industry and human health.