Effect of magnesium supplementation on endothelial function: A systematic review and meta-analysis of randomized...

Findings of past studies are inconsistent regarding the effects of magnesium (Mg) supplementation on endothelial function (EF). We performed this meta-analysis to examine the effects of magnesium supplementation on flow-mediated dilation (FMD) and carotid intima media thickness (CIMT) as markers of EF.

Literature searches of English publications in MEDLINE and EMBASE databases were conducted up to November 2017. Results are reported as weighted mean difference (MD) with 95% confidence intervals (CI) using random effects model (DerSimonian-Laird method). Cochrane's Q test and I-squared (I²) were used to determine heterogeneity among included studies. To determine potential sources of heterogeneity, subgroup analysis was conducted for pre-defined criteria. Funnel plot and Egger's regression test were used to assess publication bias.

Seven RCTs with 306 participants were included. Mg supplementation significantly increased FMD (MD: 2.97; 95% CI: 0.23 to 5.70%, p = 0.033). Between studies heterogeneity was high and subgroup analysis could not identify the sources of heterogeneity. Magnesium supplementation had no significant effect on CIMT (MD: -0.13 mm; 95% CI: 0.27, 0.01; p = 0.077) with high heterogeneity. Mg dose, duration of treatment, healthy status, baseline CIMT and sample size were the potential sources of heterogeneity. Mg supplementation could decrease CIMT to a greater extent in hemodialysis (HD) patients; lower doses of Mg, higher sample size and follow up duration and subjects with higher baseline CIMT also reduced the heterogeneity to some degree (p < 0.001).

Magnesium supplementation may improve endothelial function without affecting carotid intima media thickness.