Magnesium supplements: benefits, risks and impact on blood pressure

Research shows that magnesium supplementation can lower blood pressure, but primarily for people with a magnesium deficiency or uncontrolled hypertension. Effective doses are typically above 600 mg per day and work best when combined with antihypertensive medication. Experts advise obtaining magnesium from food such as leafy greens, legumes, whole grains, dark chocolate, nuts and bananas, and caution patients with kidney disease about excess intake.

Excessive magnesium, often from high‑dose supplements, may cause hypermagnesemia. Mild symptoms include drowsiness, nausea, diarrhea and a drop in blood pressure; severe cases can lead to irregular heartbeat, muscle weakness, breathing difficulty and, rarely, cardiac arrest. Doses exceeding 5 g daily have been linked to toxicity. Recommended daily allowances are 400‑420 mg for adult men and 310‑320 mg for adult women, with higher amounts during pregnancy. Deficiency is more common than excess, affecting up to one‑fifth of the population and causing muscle cramps and fatigue. Consultation with a physician is advised before starting high‑dose magnesium supplements, especially for individuals with chronic kidney disease.