The effect of magnesium supplementation on blood pressure: a meta-analysis of randomized clinical trials.
BACKGROUND
An increased intake of magnesium might lower blood pressure (BP), yet evidence from clinical trials is inconsistent, perhaps as a result of small sample size or heterogeneity in study design.


METHODS
We performed a meta-analysis of randomized trials that tested the effects of magnesium supplementation on BP. Twenty trials meeting the inclusion criteria were identified. Random effects models and meta-regression methods were used to pool study results and to determine the dose-response relationship of magnesium to BP.


RESULTS
The 20 studies included 14 of hypertensive and 6 of normotensive persons totaling 1220 participants. The doses of magnesium ranged from 10 to 40 mmol/day (median, 15.4 mmol/day). Magnesium supplementation resulted in only a small overall reduction in BP. The pooled net estimates of BP change (95% confidence interval [CI]) were -0.6 (-2.2 to 1.0) mm Hg for systolic BP and -0.8 (-1.9 to 0.4) mm Hg for diastolic BP. However, there was an apparent dose-dependent effect of magnesium, with reductions of 4.3 mm Hg systolic BP (95% CI 6.3 to 2.2; P < .001) and of 2.3 mm Hg diastolic BP (95% CI 4.9 to 0.0; P = .09) for each 10 mmol/day increase in magnesium dose.


CONCLUSIONS
Our meta-analysis detected dose-dependent BP reductions from magnesium supplementation. However, adequately powered trials with sufficiently high doses of magnesium supplements need to be performed to confirm this relationship.
Jee
Sun Ha
SH
Department of Epidemiology and Disease Control, Yonsei University Graduate School of Health Science and Management, Seoul, Korea.
Miller
Edgar R
ER
Guallar
Eliseo
E
Singh
Vikesh K
VK
Appel
Lawrence J
LJ
Klag
Michael J
MJ
D000328:Adult; D000368:Aged; D000704:Analysis of Variance; D001794:Blood Pressure / Q000187:drug effects*; D016001:Confidence Intervals; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D006973:Hypertension / Q000517:prevention & control*; D008274:Magnesium / Q000008:administration & dosage*; D008297:Male; D008875:Middle Aged; D016032:Randomized Controlled Trials as Topic
D008274:Magnesium