Bloomington, IN—Magnesium supplements, widely available on drugstore shelves and elsewhere, appear to modestly lower blood pressure, according to a new study.

The report about magnesium, an essential element in the human body, was published recently in the American Heart Association’s journal Hypertension.

A study team led by Indiana University researchers sought to help settle the debate about whether magnesium plays a role in regulating blood pressure; inconsistent and controversial evidence from studies in humans have left that an open question.

In an effort to answer it, the researchers conducted a meta-analysis of 34 clinical trials, involving 2,028 participants.

Results indicate that trial participants receiving a median of 368 mg of magnesium a day for an average of three months had overall reductions in systolic blood pressure of 2.00 mmHg and diastolic blood pressure of 1.78 mmHg.

The study notes that taking 300 mg/day of magnesium for just 1 month was enough to elevate blood magnesium levels and reduce blood pressure. It also suggests that high magnesium levels in the blood were linked to improvements in blood flow which can help lower blood pressure.

In the meta-analysis, the daily dosage of magnesium supplements ranged from 240 to 960 mg, 82% of which were equal to or higher than the U.S. Recommended Dietary Allowance for adults—310 to 320 mg/day for women and 400 to 420 mg/day for men.

“With its relative safety and low cost, magnesium supplements could be considered as an option for lowering blood pressure in high-risk persons or hypertension patients,” said lead author Yiqing Song, MD, ScD, associate professor in the department of epidemiology at the Richard M. Fairbanks School of Public Health at Indiana University.

Study authors caution that the applicability of their meta-analysis is limited by the small size of most of the studies, which ranged from 13 to 461 participants, and by high dropout rates. On the other hand, they point out that the higher quality studies with lower dropout rates also showed the greatest reductions in blood pressure.

An examination of sub-groups in the study raised the possibility that magnesium supplements reduced blood pressure only in those deficient in the mineral, according to the researchers.

“Consistent with previous studies, our evidence suggests that the anti-hypertensive effect of magnesium might be only effective among people with magnesium deficiency or insufficiency,” Song said. “Such suggestive evidence indicates that maintenance of optimal magnesium status in the human body may help prevent or treat hypertension.”

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