Magnesium’s role in the heart

Magnesium is one of the electrolytes that plays a role in the heart’s electrical functioning. Research seems to support this conclusion, since studies show that it can relieve atrial fibrillation.

‘Heart arrhythmia is associated with magnesium deficiency,’ explains Dr Sarah Myhill, a GP based in Powys. ‘In the heart muscle and elsewhere in the body, calcium is the mineral that is needed to help excite muscle cells and cause contractions, whereas magnesium is involved in the process of getting the muscle to relax. If you don’t have enough, the muscle doesn’t relax as it should and the rhythm of the heart can go awry.’

Although she admits this is a ‘hunch’, she believes that sudden adult death syndrome, when healthy adults drop dead during strenuous exercise like long-distance runs, could be causes by acute magnesium depletion. ‘It’s biologically plausible that people who are sweating and losing water and minerals as sweat and urine, could not have enough available magnesium to keep their heart beating. It needs further investigation.’

Canadian researchers have done a meta-analysis of studies dealing with the benefits of intravenous administration of magnesium in the acute treatment of atrial fibrillation. They found that effective rate control (reduction in heart rate below 100 bpm) and/or conversion to normal sinus rhythm was achieved in 84% of patients given magnesium as compared to 53% given a placebo. The researchers conclude that intravenous magnesium is part of an effective and safe strategy for the acute treatment of atrial fibrillation.