What do clinical trials actually say about magnesium?
Magnesium's evidence base is one of the broadest in the supplement world — 300+ enzymatic roles invite research in every system — and one of the most honest to grade: genuine, replicated effects in each condition, consistently modest in size, strongest in deficient populations. The field teaches calibrated reading better than almost any nutrient: real effects, honestly small, population-dependent, and never approaching the prescription tier.
The field's breadth teaches several reading skills:
The first dietary-deficiency demonstration — animals on magnesium-poor diets develop vasodilation, seizures, and death; the mineral joins the essential list.
The first human magnesium-deficiency cases documented — in patients with malabsorption and alcoholism, the condition's classic high-risk groups to this day.
IV magnesium becomes standard treatment for torsades de pointes and severe pre-eclampsia — the hospital-medicine era of the mineral begins.
The first randomized trials in blood pressure (600 mg oxide/citrate) and migraine (600 mg/day) — modest positive effects that established the field's honest size.
Pooled analyses confirm: type 2 diabetics are commonly magnesium-deficient (osmotic losses), and correction improves insulin sensitivity in the deficient subgroup.
L-threonate's brain-penetrant design, the glycinate tolerance advantage, and the continuing search for better deficiency diagnostics — while the food-system shortfall that started it all persists.
POPULATION · 81 adults with migraine, 12 weeks
FINDING · Attack frequency fell significantly in the magnesium group (41.6% responders vs 15.8% placebo), with benefit building over the trial period.
LIMITATION · Modest sample; trials used different magnesium salts (oxide/citrate) than the better-tolerated modern forms; oral magnesium's dose ceiling limits escalation. Now guideline Level B.
POPULATION · Adults with mild-to-moderate generalized anxiety, 300–450 mg/day magnesium + vitamin B6, 8 weeks
FINDING · Significant anxiety-score reduction versus placebo in one trial — small sample, combination intervention (magnesium + B6), single-center.
LIMITATION · The anxiety evidence base is exactly this: small, combination trials in mild populations — suggestive, not practice-changing. Our anxiety page grades it Tier 3, gentle baseline.