Background: There are inconsistent reports regarding the effect of magnesium intake on blood pressure (BP) across hypertensive and normotensive populations.
Methods: We performed a meta-analysis and dose-response analysis to explore the relationship between magnesium supplementation and BP in randomized-controlled trials with a duration of ≥4 weeks, using a cubic spline regression model.
Results: Thirty-eight randomized controlled trials involving 2709 participants were eligible for inclusion. Studies included an elemental magnesium dose from 82.3 mg to 637 mg with a median dose of 365 mg and a median intervention period of 12 weeks. Mean differences of changes in BP were calculated by random effects meta-analysis. Magnesium intake resulted in a reduction in systolic BP of -2.81 mm Hg (95% CI, -4.32 to -1.29) and diastolic BP by -2.05 mm Hg (95% CI, -3.23 to -0.88) compared with placebo. Hypertensive individuals on BP-lowering medication and individuals with hypomagnesemia yielded greater systolic BP reductions of -7.68 and -5.97 mm Hg, respectively (P<0.05), and diastolic BP reductions of -2.96 and -4.75 mm Hg, respectively (P<0.05). In normotensive groups, statistical significance was not reached. We identified high heterogeneity across studies. We found no dose-response relationship between magnesium and BP changes (all P≥0.20).
Conclusions: Our findings support the beneficial effect of magnesium on reducing BP among populations with hypertension and hypomagnesemia, although effects should be interpreted with caution due to high heterogeneity of studies. Larger, well-designed studies assessing higher magnesium doses are needed to refine the dose-response relationship between magnesium intake and BP and identify potential optimal supplementation strategies for subpopulations.
Keywords: blood pressure; cardiovascular disease; diet; hypertension; magnesium.