The effects of oral magnesium supplements on vascular and endothelial function: an updated systematic review and meta-analysis of randomized controlled trials

Magnesium has been suggested to play a role in cardiovascular health through its effects on endothelial function, vascular stiffness, and blood pressure. This systematic review and meta-analysis aimed to update and evaluate the effect of magnesium supplementation on vascular function and cardiometabolic outcomes in adults. A systematic search based on PRISMA 2020 guidelines was conducted on PubMed, Web of Science, Scopus, CENTRAL, and ClinicalTrials.gov up to 23 April 2026 to include randomized placebo-controlled trials assessing the effects of magnesium supplementation on flow-mediated dilation (FMD), pulse wave velocity (PWV), and carotid intima-media thickness (CIMT), and as secondary outcomes for serum magnesium levels and systolic and diastolic blood pressure. Random-effect model, subgroup analyses (dose, duration, formulation), meta-regression, sensitivity analyses, and publication bias assessment were performed as well. A total of twelve randomized controlled trials comprising 389 patients in the magnesium group and 276 patients in the placebo group were included in this study. Magnesium supplementation showed no significant overall effect on FMD (MD = 2.86; 95% CI: − 1.31 to 7.03; p = 0.18). However, doses > 400 mg/day significantly improved FMD (MD = 8.32; 95% CI: 3.45 to 13.19; p < 0.01), but it included 2 studies. CIMT was significantly reduced (MD = − 0.08; 95% CI: − 0.15 to − 0.01; p = 0.03), while PWV showed no significant change (MD = − 0.17; 95% CI: − 0.60 to 0.25; p = 0.43). Serum magnesium increased significantly (MD = 0.05; 95% CI: 0.02 to 0.07; p < 0.01) in overall and in subgroups, whereas blood pressure reductions were not statistically significant ( p > 0.3). Meta-regression showed significant modifying effects of higher magnesium doses and higher baseline SBP on FMD, and a significant inverse correlation of baseline body mass index (BMI), baseline PWV, and baseline CIMT on FMD. Magnesium supplementation may improve endothelial function and reduce CIMT, particularly at higher doses, although it should be interpreted cautiously because of limited studies and inconsistent effects on arterial stiffness and blood pressure. Further large-scale trials are required to confirm optimal dosing strategies and clinical benefits.