But because the research focused on magnesium in food, the authors stopped short of recommending that people take a daily magnesium supplement. It's possible that another aspect of the food is responsible for the finding.
What the results do suggest is that people eat a healthy diet with "magnesium-rich foods such as green leafy vegetables, nuts, beans and whole grains," said lead author Susanna Larsson, a professor at the Karolinska Institutet in Stockholm, Sweden.
Larsson and her colleagues combed through research databases spanning the last 45 years to find studies that tracked how much magnesium people ate and how many of them had a stroke over time.
In seven studies published in the past 14 years, about 250,000 people in the US, Europe and Asia were followed for an average of 11.5 years. About 6,500 of them, or three percent, had a stroke in the time they were followed.
For every extra 100 milligrams of magnesium a person ate per day, their risk of an ischemic stroke -- the most common kind, typically caused by a blood clot -- fell by nine per cent.