Nearly half of all people who die of heart disease die suddenly, the cause of death being sudden cardiac arrhythmia. Arrhythmia is a condition where the normal rhythmic contraction of the heart is disturbed with a resulting failure in circulation, resulting in ischaemia and death. Magnesium and potassium ions are present in cardiac cells and high concentrations are needed for the correct function of cardiac tissue. Magnesium deficiency has been implicated in certain types of cardiac dysfunction. For example, low dietary magnesium has been linked to the development of supraventricular ectopic beats1, and patients with the lowest levels of erythrocyte magnesium have the lowest levels of dietary magnesium. It is known that a greater proportion of deaths due to sudden cardiac anthemia occur in cities with soft drinking water, that is lacking both magnesium and potassium.
According to research, magnesium and potassium deficiencies in animals can lead to changes in neuromuscular function such as cramps, spasms, tremors, tetany and convulsions. These changes are most frequently associated with hypomagnesaemia, but also with hypocalcaemia and hypokalaemia. A paper published in the American Journal of Clinical Nutrition in 19792 demonstrated that subjects dying sudden of ischeamic heat disease had significantly lower levels of myocardial tissue magnesium and potassium that control (men dying of trauma). The study found that the four lowest potassium levels were found in the only men with a history of angina, and three of these men also had the lowest tissue magnesium levels. Research has shown that magnesium intakes for Western populations are generally below the recommended levels, and some studies suggest that these levels are set too low for optimum health.