Study
Randomized, open-label study of the short-term pharmacokinetics of oral magnesium oxide in healthy volunteers.
A single 2,000 mg magnesium-oxide dose did not raise short-term systemic exposure proportionally above 750 mg in 24 healthy men.
Summary Does taking more magnesium oxide lead to much more magnesium entering the bloodstream? Show / hide ↓
Researchers randomly gave one magnesium oxide dose to 24 healthy men aged 18 to 45. Twelve took 750 milligrams, and 12 took 2,000 milligrams. They measured magnesium in the blood for 12 hours, including the highest level and the total amount measured over time. The larger dose did not produce a proportionally higher blood level or total exposure, although it reached its peak sooner. Both doses were tolerated without serious or stomach-related side effects.
What this means for you: This small, one-time study does not show that taking much more magnesium oxide gives proportionally greater short-term absorption. It does not prove which dose is best for correcting deficiency or improving health, so do not use it alone to justify buying or taking a high dose.
early evidenceThis randomised, open-label pharmacokinetic study examined absorption after a single oral dose of magnesium oxide in 24 healthy men aged 18-45 years. Twelve received 750 mg and 12 received 2,000 mg. Serum magnesium was measured from baseline through 12 hours, and the investigators calculated Cmax, Tmax and AUC0-12. They did not estimate half-life, AUC0-infinity, clearance or mean residence time because the 12-hour samples did not show a clear terminal log-linear phase. The higher dose did not produce a proportional increase in Cmax or AUC, and incremental exposure measures were also similar between doses. Tmax was shorter with 2,000 mg than with 750 mg (p=0.025). Both doses were tolerated without serious adverse events or gastrointestinal side effects. This is an acute absorption study, not an efficacy trial. It shows that more magnesium oxide did not translate into proportionately greater measured systemic exposure over 12 hours. The abstract explicitly says these exploratory pharmacokinetic results should not be extrapolated to clinical efficacy or perioperative dosing.
Oral magnesium oxide showed non-proportional systemic exposure across the 750-2,000 mg range during the 12-hour observation period.
The sample was 24 healthy male volunteers, with one dose and only 12 hours of follow-up. Serum pharmacokinetics are a surrogate and do not establish a clinical benefit.
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