A study that was published in the American Heart Journal (2010; 160(3): 464-70) looked at the relationship between sudden cardiac death and magnesium levels in the serum of 14,232 subjects between the ages of 45 and 64. Researchers found an inverse association between serum magnesium levels and the incidence of sudden cardiac death. In the 12 years (average) of follow-up, there were 264 cases of sudden cardiac death. The subjects with magnesium levels in the highest quartile of serum magnesium had a 38% lower risk of sudden cardiac death when compared to the subjects in the lowest quartile.