Friday Aug 23, 2013 (foodconsumer.org) -- A new study in Journal of the American Heart Association suggests that eating foods high in magnesium may help reduce the risk of fatal coronary heart disease even though either serum magnesium or dietary magnesium was not associated with the risk of total coronary heart disease.

Stephanie Chiuve, ScD from Division of Preventive Medicine Harvard Medical School in Boston, MA and colleagues conducted the study and found those in the highest quintile of magnesium intake were 39% less likely to suffer fatal coronary heart disease than those in the lowest quintile.

The authors say in their study report that magnesium, a mineral that humans need for normal physiology, has already been associated with lower risk of sudden cardiac death.  Laboratory studies also show that magnesium affects endothelial function, inflammation, blood pressure, and diabetes mellitus.

The current study was intended to establish a direct relation between dietary and plasma magnesium and the risk of coronary heart disease (CHD).

For the study, researchers prospectively examined the association between dietary and plasma magnesium and risk of coronary heart disease among 86 323 women in the Nurses' Health Study.   Participants were free of heart disease in 1980 when entering the study and information on magnesium intake and lifestyle factors was surveyed every 2 to 4 years through questionnaires. 

The researchers found higher magnesium intake was not associated with lower risk of total coronary heart disease or nonfatal coronary heart disease even though it was associated with fatal coronary heart disease risk.

The researchers say that the association between magnesium intake and the risk of fatal coronary heart disease seemed to be mediated at least partially by hypertension or high blood pressure.

Serum magnesium levels were also associated with 33% lower risk of coronary heart disease when the mineral level reaches above 2.0 mg/dL even though the association was not independent of other biomarkers of heart disease.

The researchers concluded "Dietary and plasma magnesium were not associated with total CHD incidence in this population of women. Dietary magnesium intake was inversely associated with fatal CHD, which may be mediated in part by hypertension." (David Liu)