Health effects of magnesium deficiency in drinking water – the case of water desalination

Seawater desalination is an important source of drinking water in increasing number of countries. In Israel, the use of desalinated water is on the rise and it is expected that in a few years the main source of drinking water will be desalinated water. Most desalination plants apply reverse osmosis, leaving minimal concentrations of minerals. Drinking water contributes about 20% of magnesium intake and the lack of magnesium in the water may lead to magnesium deficiency. This deficiency may increase morbidity and mortality from various diseases, particularly cardiovascular diseases. A systematic review was conducted in order to identify studies that examined the health effects of drinking water magnesium concentration. Fourteen studies that examined the association between magnesium concentration and cardiovascular morbidity or mortality were identified. Six of eleven studies and one of three studies found that higher magnesium concentration in drinking water had a protective effect against myocardial infarction and cerebrovascular disease, respectively. A meta-analysis of these studies reported an overall protective effect (OR = 0.75, 95% CI: 0.68-0.82). The range of magnesium concentrations measured in studies was large. We performed a cost-utility analysis of the possible effects of adding magnesium to desalinated water in Israel. Adding 30 mg magnesium/Liter of water can lead to possible reduction of 250 yearly deaths from coronary heart disease, with a cost of 23,000$ per QALY. In conclusion, more and better epidemiological studies to examine the effects of drinking water magnesium deficiency are required. However, intervention may start simultaneously with those studies. Adding magnesium to desalinated drinking water is simple, effective, safest and most equal public health measure compared with other interventions such as using nutritional supplements or magnesium enrichment of food. It should be considered taking into account the implementation costs and technological feasibility.