Consuming magnesium appears to reduce the risk for cerebral infarction in male smokers, according to a report in the March 10 issues of Archives of Internal Medicine, one of the JAMA/Archives journals.

A cerebral infarction is a particular kind of stroke that occurs because blood flow in the brain is blocked. This can be caused by a few factors, including blood clots or internal bleeding. Research has recently shown that dietary modifications could help prevent stroke. Since hypertension, or high blood pressure, is one of stroke’s risk factors, dietary measures that reduce blood pressure could affect stroke risk. Consuming more magnesium, calcium, and potassium is associated with a lower blood pressure, while sodium has the opposite effect.

To examine the role of each of these dietary factors on the instance of cerebral infarction, Susanna C. Larsson, Ph.D., of the Karolinska Institutet, Stockholm, Sweden, and colleagues studied the diets of 26,556 Finnish male smokers aged between 50 to 69 years old who had no history of stroke. In addition to their diets, the men were examined for various medical characteristics, for their physical activity histories, and for their smoking habits. Specifically, their hight, weight, and blood pressure were noted and a blood sample was taken for further analysis.

Averaging 13.6 years of follow-up, approximately 10% (2,702) of the men suffered cerebral infarctions. Of these, 14% (383 men) had intracerebral hemorrhages, which are identified by bleeding into the brain tissue, and 7% (196) had subarachnoid hemorrhages, which involve bleeding between the brain and its outer tissues. 3% (84 patients) had unspecified types of strokes.

Adjusting for age and for cardiovascular risk factors such as diabetes and cholesterol, the men who consumed the most magnesium, with an average of 589 milligrams per day) had a 15% lower risk of cerebral infarction than those who consumed the least, who ingested an average of 373 milligrams per day. This link was most pronounced in men younger than 60 years old. This magnsium contact was not linked to a lower risk of intracerebral or subarachnoid hemorrhage. Additionally, calcium, potassium, and sodium intake were not associated with any risk for any type of stroke.

The authors state that this is a physiologically reasonable linkage. “An inverse association between magnesium intake and cerebral infarction is biologically plausible,” they write. Additionally, magnesium may affect cholesterol concentration or the body’s use of insulin in glucose absorption metabolism. Either of these could influence cerebral infarction without affecting hemorrhage.

This study could lead to further research in this direction. These results “suggest that a high consumption of magnesium-rich foods, such as whole-grain cereals, may play a role in the prevention of cerebral infarction,” the authors explain. “Whether magnesium supplementation lowers the risk of cerebral infarction needs to be assessed in large, long-term randomized trials.”

Magnesium, Calcium, Potassium, and Sodium Intakes and Risk of Stroke in Male Smokers
Susanna C. Larsson, PhD; Mikko J. Virtanen, MSc; Monica Mars, PhD; Satu Männistö, PhD; Pirjo Pietinen, DSc; Demetrius Albanes, MD; Jarmo Virtamo, MD
Arch Intern Med. 2008;168(5):459-465.
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Written by Anna Sophia McKenney