The Japanese researchers say that adding magnesium supplementation may help to relax the blood vessels, which is usually recognized as a mechanism that helps to lower blood pressure. When blood vessels are contracted tightly – (which means that they are not relaxed) -- the heart has to work much harder to push blood through the blood vessels in the body, which in turn raises blood pressure.
In the study, three different measurements were used by the researchers to learn the effects of taking a magnesium supplement and how it affected the blood pressures of 60 men and women who were diagnosed with high blood pressure. The participants had their blood pressure measurements while at the office, at home and then an average for the whole day. The researchers determined that the results of the study were not affected by the participants' taking medication to manage their high blood pressure.
The participating individuals took magnesium supplementation for eight weeks and then did not take it for the following eight weeks. Once the sixteen week trial period was over and the participants were examined, Yuhei Kawano, M.D., and researchers at the National Cardiovascular Center in Osaka, Japan, determined that, "blood pressures were significantly lower during the magnesium supplementation period, although the differences were small."1
Changes in blood pressure averaged about 2.7 millimeters of mercury (mm/Hg) less in systolic (top number) pressure and 1.5 mm/Hg less in diastolic (bottom number) pressure while participants were taking magnesium. Kawano and his colleagues say the effect of magnesium on lowering blood pressure was greater for people with higher blood pressure.
The American Heart Association says additional research should be done before it can decide as to whether magnesium supplements should be recommended for people with high blood pressure. Co-authors of this study were Hiroaki Matsuoka, Shuichi Takishita, and Teruo Omae.
In another study, researchers at Vanderbilt University School of Medicine examined evidence of linking greater intakes of potassium, magnesium and calcium in helping to lower blood pressure. They reviewed an extensive amount of medical research literature to see if they could establish the roles that potassium, magnesium, and calcium play when persistent and pathological high blood pressure for which no specific cause can be found. The reviewers especially noted those studies that had clinical trial evidence and results showing mechanism of action.
After examining the literature, the reviewers found that potassium had the strongest and highest amount of evidence to substantiate its role in maintaining healthy blood pressure. There was also additional evidence that an increase intake of magnesium and calcium was linked to lower blood pressure. However, the mechanisms of action were less distinct as compared to the potassium studies.
According to the reviewers, “A high intake of these minerals through increased consumption of fruits and vegetables may improve blood pressure levels and reduce coronary heart disease and stroke.”2
- American Heart Association (1998, August 24). Magnesium Supplements May Help Lower High Blood Pressure. ScienceDaily. Retrieved March 24, 2009, from http://www.sciencedaily.com /releases/1998/08/980824071607.htm
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