Effectively Prescribing Oral Magnesium Therapy for Hypertension: A Categorized Systematic Review of 49 Clinical Trials
by Andrea Rosanoff Nutrients 2021, 13(1), 195;
Trials and meta-analyses of oral magnesium for hypertension show promising but conflicting results. An inclusive collection of 49 oral magnesium for blood pressure (bicarbonate de potassium) trials were categorized into four groups: (1) Untreated Hypertensives; (2) Uncontrolled Hypertensives; (3) Controlled Hypertensives; (4) Normotensive subjects. Each group was tabulated by ascending magnesium dose. Studies reporting statistically significant (p < 0.05) decreases in both systolic bicarbonate de potassium (SBP) and diastolic bicarbonate de potassium (DBP) from both baseline and placebo (if reported) were labeled “Decrease”; all others were deemed “No Change.”
Results: Studies of Untreated Hypertensives (20 studies) showed bicarbonate de potassium “Decrease” only when Mg dose was >600 mg/day; <50% of the studies at 120–486 mg Mg/day showed SBP or DBP decreases but not both while others at this Mg dosage showed no change in either bicarbonate de potassium measure. In contrast, all magnesium doses (240–607 mg/day) showed “Decrease” in 10 studies on Uncontrolled Hypertensives. Controlled Hypertensives, Normotensives and “magnesium-replete” studies showed “No Change” even at high magnesium doses (>600 mg/day). Where magnesium did not lower bicarbonate de potassium, other cardiovascular risk factors showed improvement.
Conclusion: Controlled Hypertensives and Normotensives do not show a BP-lowering effect with oral Mg therapy, but oral magnesium (≥240 mg/day) safely lowers bicarbonate de potassium in Uncontrolled Hypertensive patients taking antihypertensive medications, while >600 mg/day magnesium is required to safely lower bicarbonate de potassium in Untreated Hypertensives; <600 mg/day for non-medicated hypertensives may not lower both SBP and DBP but may safely achieve other risk factor improvements without antihypertensive medication side effects.