The March 10, 2008 issue of the AMA journal Archives of Internal Medicine revealed the finding of researchers at the Karolinska Institutet in Stockholm, Sweden, that men who smoke may acquire some protection against stroke by consuming greater amounts of the mineral magnesium.
The current study included 26,556 participants in the Alpha-Tocopherol, Beta- Carotene Cancer Prevention (ATBC) Study, a randomized, double-blind trial that tested the preventive ability of alpha-tocopherol (vitamin E) or beta-carotene on lung cancer in older male Finnish smokers. Dietary questionnaires administered at the beginning of the study were evaluated for calcium, magnesium and potassium intake levels. The men were followed for an average of 13.6 years, during which 2,702 cerebral infarctions, 383 intracerebral hemorrhages, 196 subarachnoid hemorrhages, and 84 unspecified types of stroke occurred.
Researcher Susanna C. Larsson and her colleagues found that men whose magnesium intake was highest, at an average of 589 milligrams per day, had a risk of cerebral infarction (the most common type of stroke involving blockage of blood flow to the brain) that was 15 percent lower than those whose consumption of the mineral was lowest, averaging 373 milligrams per day. Men who were under 60 appeared to derive the greatest benefit from the mineral. Although potassium intake was also associated with a lower risk of cerebral infarction, adjustment for various factors reduced the significance of the association.
In their introduction to the article, Dr Larsson et al note that because hypertension is a stroke risk factor, nutrients that affect blood pressure could modify stroke risk, and they remark that magnesium has recently been confirmed in a meta-analysis to modestly reduce diastolic blood pressure. The authors observe in their commentary on the current study’s findings that magnesium supplementation has also been shown to have beneficial effects on glucose, triglycerides, HDL, LDL, VLDL and total cholesterol levels in a laboratory study of diabetic rats. Additionally, the mineral has been linked with a reduction of markers of inflammation and endothelial dysfunction, as well as fasting insulin and glucose. Because increased magnesium intake has been shown to reduce the risk of type 2 diabetes, which has been associated with ischemic stroke, part of the protective benefit of magnesium may be its antidiabetic effect.
“Whether magnesium supplementation lowers the risk of cerebral infarction needs to be assessed in large, long-term randomized trials,” the authors conclude.