Pooling data from seven prospective studies revealed that, for every 100 mg per day increase in magnesium intake, the risk of stroke was reduced by about 9%.
“Although it is premature to recommend magnesium supplementation to reduce risk of stroke, increased consumption of magnesium-rich foods such as green leafy vegetables, beans, nuts, and whole-grain cereals appears to be prudent,” wrote the Swedish scientists in the American Journal of Clinical Nutrition.
Need for an RCT
The meta-analysis was described as “well-done” in an accompanying editorial by Yiqing Song from Harvard Medical School and Simin Liu from UCLA.
Song and Liu note that scientists have been studying the role of magnesium in cardiovascular health for about 80 years, and that, without a large randomized clinical trial, “it is safe to predict that another 8 decades will go by while generations of nutritional scientists continue to debate magnesium’s efficacy for the primary prevention of CVD”.
Minerals and stroke
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 have been inversely linked to hypertension in some observational studies.
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).
Susanna Larsson, Nicola Orsini, and Alicja Wolk from the Karolinska Institutet in Stockholm conducted a dose reponse meta-analysis of seven studies including 241,378 participants.
Results showed that every increase in magnesium intake of 100 mg per day was associated with an 8% and 9% reduction in the risk of total and ischemic stroke, respectively. No association was observed between magnesium intake and other forms of stroke, however.
Commenting on the potential mechanism behind the minerals apparent benefits, the Swedish scientists said that several potential mechanisms are plausible. These include a blood-pressuring lowering effect, or a role for magnesium in reducing the risk of type-2 diabetes.
In the editorial, Song and Liu called for “a better understanding of mechanisms to enable that eventual large efficacy trial.
“For example, integrating dietary and genetic markers of magnesium homeostasis with intermediate CVD phenotypes has provided additional insight concerning the homeostatic
regulation of magnesium metabolism and its role in the etiology of CVD.”
Source: American Journal of Clinical Nutrition
Published online ahead of print, doi: 10.3945/ajcn.111.022376
“Dietary magnesium intake and risk of stroke: a meta-analysis of prospective studies”
Authors: S.C. Larsson, N. Orsini, A. Wolk
Editorial: American Journal of Clinical Nutrition
Published online ahead of print, doi:10.3945/ajcn.111.031104
“Magnesium for cardiovascular health: time for intervention”
Authors: Y. Song, S. Liu