Magnesium and Blood Pressure

What the evidence shows

A 2016 meta-analysis published in Hypertension pooled 34 randomized, double-blind, placebo-controlled trials involving 2,028 normotensive and hypertensive adults. Oral magnesium supplementation at a median dose of about 368 mg/day for a median of 3 months was associated with a small average reduction in blood pressure, lowering systolic blood pressure by roughly 2 mm Hg and diastolic blood pressure by roughly 1.8 mm Hg compared with placebo. These reductions were accompanied by a small rise in serum magnesium.^{[1], [2]}

A separate 2017 systematic review and meta-analysis of randomized controlled trials, focused on cardiovascular risk factors in adults with and without type 2 diabetes, reported a comparable small reduction in systolic blood pressure of about 3 mm Hg with magnesium supplementation. This convergence across populations adds context, with a more pronounced effect noted in diabetic subjects who had low magnesium levels.^{[1], [2]}

Doses studied

In the pooled trials, the amounts examined generally fell in the range of about 300 to 368 mg/day of oral magnesium taken over roughly 1 to 3 months. The authors observed that a dose of about 300 mg/day or a duration of about 1 month was sufficient to raise serum magnesium and produce a measurable change in blood pressure. These figures describe the amounts tested in research rather than a recommended intake, and individual needs differ.^[1]

Limitations

The reported effects are small in absolute terms, and the pooled estimates carried meaningful statistical heterogeneity, meaning results varied across trials. Most studies were short, lasting only a few months, and the authors of both meta-analyses explicitly called for further well-designed trials before drawing firm conclusions. This information is educational and is not a substitute for individualized medical care.^{[1], [2]}

Limitations of the evidence

The blood-pressure effect of magnesium supplementation is modest and was measured over short study periods, with notable variation between trials. Findings come from supplementation studies in research settings and may not generalize to every individual; anyone considering magnesium for cardiovascular reasons should consult a qualified health professional.^{[1], [2]}