Low magnesium levels may increase stroke risk

Low blood levels of magnesium may increase the risk of stroke by 25 per cent, suggest findings from the Atherosclerosis Risk in Communities Study.
According to findings published in the American Journal of Epidemiology, increasing levels of the mineral could decrease the risk of ischemic stroke, with the effects related to magnesium’s benefits on blood pressure and for diabetics.

Diet is known to have an impact on a person's risk of having a stroke, and in particular a connection has been made between intake of sodium and hypertension. Conversely, more magnesium, potassium and calcium has been inversely linked to hypertension in some observational studies.

The new study supports the potential of magnesium to reduce the risk of stroke possibly via an anti-hypertensive mechanism, suggest the researchers, led by Aaron Folsom from the University of Minnesota’s School of Public Health.

Dietary sources of magnesium include green, leafy vegetables, meats, starches, grains and nuts, and milk. Earlier dietary surveys show that a large portion of adults does not meet the RDA for magnesium (320 mg per day for women and 420 mg per day for men).

Study details

Over 14,000 men and women aged between 45 and 64 took part in the study, and during the course of 15 years of follow-up the researchers documented 577 cases of ischemic stroke. The incidence of stroke was highest amongst diabetics and people with hypertension, added the researchers.

Blood levels of magnesium were negatively associated with the risk of stroke, they said, with levels of 1.6, 1.7, and 1.8 mEq/L linked to a 22, 30, and 25 per cent reduction in stroke, respectively, compared to 1.5 mEq/L.

After the results were adjusted for hypertension and diabetes, the researchers found that the links became non-significant.

"Dietary magnesium intake was marginally inversely associated with the incidence of ischemic stroke," wrote Folsom and his co-workers.

"Low serum magnesium levels could be associated with increased risk of ischemic stroke, in part, via effects on hypertension and diabetes," they concluded.

Magnesium and diabetes

A meta-analysis of prospective cohort studies by researchers at Stockholm's Karolinska Institutet, reported that for every 100 milligram increase in magnesium intake, the risk of developing type-2 diabetes decreased by 15 per cent.

Writing in the Journal of Internal Medicine Susanna Larsson and Alicia Wolk concluded that while it is too early to recommend magnesium supplements for type-2 diabetes prevention, increased consumption of magnesium-rich food "seems prudent."

Source: American Journal of Epidemiology
Published online ahead of print, 16 April 2009, doi:10.1093/aje/kwp071
"Serum and Dietary Magnesium and Risk of Ischemic Stroke - The Atherosclerosis Risk in Communities Study"
Authors: T. Ohira, J.M. Peacock, H. Iso, L.E. Chambless, W.D. Rosamond, A.R. Folsom