DALLAS, August 21 -- Magnesium supplements have a small but significant effect on lowering blood pressure, according to a study in this month's Hypertension: Journal of the American Heart Association.
The authors of the study say that these findings should clarify inconsistent results from previous investigations of magnesium and blood pressure. Some results have indicated that magnesium helps lower blood pressure while others haven't.
Japanese researchers say magnesium may play a role in relaxing the blood vessels, an effect generally proven to help lower blood pressure. When blood vessels are constricted -- not relaxed -- the heart works harder to pump blood through the body, causing blood pressure to increase.
The researchers used three different measurements to study how taking a magnesium supplement affected the blood pressures of 60 men and women with high blood pressure. Blood pressure measurements were taken at the office, at home and as an average for the whole day. Results of the study were not affected by the participants' taking medication to control their high blood pressure, the researchers say.
After examining individuals following eight weeks on magnesium and eight weeks off, 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." 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 is needed before it can determine whether magnesium supplements should be recommended for people with high blood pressure.
Co-authors of the study are Hiroaki Matsuoka, Shuichi Takishita, and Teruo Omae.