Magnesium confers BP-lowering benefits in people with hypertension, hypomagnesemia

Magnesium supplementation appears to substantially reduce blood pressure (BP) levels in individuals with hypertension and hypomagnesemia, especially those on antihypertensive medication, according to a systematic review and meta-analysis.

Researchers searched multiple online databases for randomized controlled trials (RCTs) in which the effect of supplementation with magnesium on BP was examined. The studies had to have a population of adults, assessed systolic and diastolic BP during follow-up, included an intervention period of at least 4 weeks, and had a placebo or control group.

A total of 38 RCTs involving 2,709 participants that met the inclusion criteria were included in the meta-analysis. The interventions included elemental magnesium supplementation at doses ranging from 82.3 to 637 mg (median dose 365 mg) and lasting a median of 12 weeks.

Random-effects meta-analysis showed that magnesium intake resulted in a reduction of 2.81 mm Hg (95 percent confidence interval [CI], −4.32 to −1.29) in systolic BP and of 2.05 mm Hg (95 percent CI, −3.23 to −0.88) in diastolic BP as compared with placebo.

More pronounced benefits were observed in hypertensive individuals on BP-lowering medications and those with hypomagnesemia, with systolic BP reductions of −7.68 and −5.97 mm Hg (p<0.05) and diastolic BP reductions of −2.96 and −4.75 mm Hg (p<0.05), respectively.

No dose-response association was seen between magnesium supplementation and BP changes (p≥0.20 for all).

Heterogeneity was high across studies.

The present data support the beneficial effect of magnesium on lowering BP among populations with hypertension and hypomagnesemia, although effects should be interpreted with caution due to high heterogeneity of studies, the researchers said. They called for larger, well-designed studies assessing higher magnesium doses to further investigate a dose-response effect and identify potential optimal supplementation strategies for subpopulations.