Magnesium supplementation confers no cardiovascular benefit

Supplementation with oral magnesium for 24 weeks hardly produces any change in arterial stiffness or blood pressure (BP), as do magnesium oxide and magnesium sulphate, as shown in a study.

The study randomized 164 individuals (mean age 63.2 years, 63.4 percent female) who were overweight or slightly obese (mean body mass index 28.1 kg/m²) to receive magnesium citrate (n=46), magnesium oxide (n=46), magnesium sulfate (n=46), or placebo (n=26) for 24 weeks. The total daily dose of magnesium was 450 mg/d.

Of the participants, 25 (15.2 percent) were on antihypertensive drugs, with 11 (6.7 percent) using diuretics. There were 10 (6.1 percent) who used lipid‐lowering drugs.

The primary outcome of carotid‐to‐femoral pulse wave velocity, which is the gold standard method for measuring arterial stiffness, did not change significantly with magnesium citrate or the other formulations as compared with placebo.

Relative to placebo, magnesium citrate supplementation led to an increase in plasma (0.04 mmol/L, 95 percent confidence interval [CI], 0.02–0.06) and urine magnesium (3.12 mmol/24 h, 95 percent CI, 2.23–4.01).

Effects on plasma magnesium were comparable among the magnesium supplementation groups, but magnesium citrate produced a greater increase in 24‐hour urinary magnesium excretion than magnesium oxide or magnesium sulphate.

Commonly reported adverse events were flatulence (n=10), stomach pain (n=13), and mild diarrhoea (n=13). One female participant in the magnesium sulphate group had a stroke during week 3 of the study, but the event was considered unrelated to the study treatment, and the participant was able to continue the study.

The findings suggest that magnesium supplements may not be beneficial in terms of arterial stiffness for individuals with normal arterial stiffness values. More studies are needed to establish their benefit in those with increased arterial stiffness, such as patients with chronic kidney disease.