Magnesium supplements taken daily for three months may result in slightly lower blood pressure, according to an analysis of more than 30 existing studies.
Previous evidence has suggested that magnesium deficiency may be related to cardiometabolic disorders, including high blood pressure, said lead author Yiqing Song.
“Taking oral magnesium supplements regularly can help lower blood pressure and can be considered as an inexpensive, safe, and adjuvant antihypertensive therapy,” said Song, of the Richard M. Fairbanks School of Public Health at Indiana University in Indianapolis.
But magnesium supplements can cause gastrointestinal symptoms, and may interfere with medications.
“Patients with heart disease, kidney disease, liver disease or other critically ill conditions should not take magnesium supplements without their doctor’s consent and supervision,” Song added.
Patients with heart disease, kidney disease, liver disease or other critically ill conditions should not take magnesium supplements without their doctor’s consent
The researchers combined data from 34 clinical trials that included a total of more than 2,000 people. Based on those results, they found that taking daily supplements of about 368mg magnesium for about three months seemed to reduce blood pressure measurements by between 1mm and 2mm Hg.
Finding safe ways to lower blood pressure, even modestly, could have significant public health impact, the study authors note in the journal Hypertension.
People taking these supplements also had higher levels of magnesium in their blood than those taking placebo, which suggests – but does not prove – that the magnesium is responsible for the slight lowering of blood pressure readings in the group taking the supplements.
The US Recommended Dietary Allowance for magnesium is 310mg to 320mg per day for women and 400 to 420 mg per day for men. Half a cup of boiled spinach contains almost 80mg of magnesium, and beans, nuts and other leafy greens are also good sources of the mineral.
The supplements were well-tolerated, Song said, but some people experienced non-serious side effects like mild abdominal pain, diarrhea, soft stool, nausea and vomiting.
It’s still not clear how magnesium lowers blood pressure, he noted.