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.
In the new study published in the Archives of Internal Medicine , researchers from the Karolinska Institutet in Sweden set out to examine the association between these minerals and the risk of stroke in male smokers.
They found that, of the four, magnesium intake in the diet, from sources such as whole grains, appeared to significantly reduce the risk of cerebral infarction.
The association could not be extended to supplementation, however, without further research.
The researchers said in their conclusion that the mechanism to explain the observation is not clear, but their findings "suggest that a high consumption of magnesium-rich foods, such as whole-grain cereals, may play a role in the prevention of cerebral infarction."
As to whether the magnesium supplementation could have the same effect, they said that large, long-term randomised trials are required.
Susanna Larsson, PhD, and her team used prospective data from the Alpha-Tocopherol, Beta Carotene Cancer Prevention (ATBC) study, which was primarily designed to see whether alpha-tocopherol and beta-carotene could reduce lung cancer incidence in men who smoke.
It followed data on a cohort of 29,133 men, aged 50 to 69 years, who smoked five or more cigarettes a day at baseline over a 13.6 year period.
The men were recruited between 1985 and 1988 in southwestern Finland, and they reported on their diet at baseline using a food frequency questionnaire including 276 food items and mixed dishes commonly consumed in Finland.
Over the follow-up period, a total of 3365 men suffered a stroke (2702 cerebral infarctions, 383 intracerebral hemorrhages, 196 sub arachnoid hemorrhages and 84 unspecified strokes.
Larsson adjusted the results for age, cardiovascular risk factors (like diabetes and cholesterol levels).
She found that men who reported consuming the most magnesium - an average of 589 mg per day - had a 15 per cent lower risk of cerebral infarction than those who consumed the least (average 373mg per day).
This association was most pronounced in men under 60 years.
No association was seen between magnesium intake and risk of intracerebral or subarachnoid stroke.
Moreover, calcium, potassium and sodium were not associated with risk of any type of stroke.
Source: Archives of Internal Medicine 2008, Volume 168, Number 5, Pages 459-465 "Magnesium, calcium, potassium and sodium intakes and risk of stroke in male smokers."
Authors: S. Larsson, M. Virtanen, M. Mars, S. Mannisto, P. Pietinen, D. Albanes, J. Virtamo