Long-term magnesium supplementation improves arterial stiffness in overweight and obese adults: results of a randomized, double-blind, placebo-controlled intervention trial.

Randomized, double-blind, placebo-controlled trial in Maastricht, Netherlands. In the active magnesium arm, 26 apparently healthy adults aged 45 to 70 years with BMI 25 to 35 kg/m2 were enrolled; participants were overweight or slightly obese, had no active cardiovascular disease or diabetes, and were not taking antihypertensive medication.

Oral magnesium citrate complex providing 350 mg/day elemental magnesium, given as 3 capsules per day (116.7 mg magnesium per capsule) after breakfast, lunch, and dinner for 24 weeks, compared with placebo.

Twenty-four weeks of magnesium citrate supplementation improved arterial stiffness versus placebo in overweight and obese adults. Carotid-femoral pulse wave velocity decreased to 8.3 m/s at 24 weeks and was significantly better than placebo by 1.0 m/s (95% CI 0.4, 1.6; P = 0.001). Office and 24-hour ambulatory blood pressure did not change, and no adverse events were observed. Serum magnesium did not significantly differ at 12 weeks and only tended to increase at 24 weeks, while 24-hour urinary magnesium excretion increased significantly.

The active intervention arm was small (N = 26), and the trial was conducted at a single center in a relatively specific group of apparently healthy overweight or slightly obese Dutch adults, limiting generalizability. Follow-up was only 24 weeks, and clinically harder cardiovascular outcomes were not assessed. Ethnicity was not reported, and secondary biomarker findings were limited or partly null.