Magnesium Oxide
Magnesium bound to oxygen. The simplest and densest form sold. Also sold as Magnesia, MgO. No authority has published an intake figure for magnesium oxide itself. The figures further down are magnesium’s, and this page says what they count.
Stacky is an organisational tool, not a medical device. It does not provide medical advice, and nothing on this page says what magnesium oxide does. Talk to a doctor or pharmacist before starting, stopping or changing what you take.
The number on the bottle and the number in the limit
Intake references for a mineral are set on the element. When EFSA writes 250 mg for magnesium, it means 250 milligrams of magnesium, the metal itself.
A supplement label can mean either of two things by a milligram. Some brands declare the magnesium delivered. Others declare the mass of the whole compound, magnesium plus whatever it is bound to. The magnesium is only a fraction of that weight, and the fraction is different for every salt.
| Form | Magnesium by weight |
|---|---|
| Magnesium oxide | about 60% |
| Magnesium malate | about 15% |
| Magnesium glycinate | about 14% |
| Magnesium citrate | about 11% to 16% |
| Magnesium L-threonate | about 8% |
Calculated from each compound’s anhydrous formula (MgO for magnesium oxide) using standard atomic weights. Real product is usually a little lower, because these salts are often sold hydrated. This is our arithmetic, not a regulator’s figure.
A label that declares the element writes it like this. The figure is magnesium, and it is the number the references below are about.
Magnesium (as magnesium oxide) ................ 300 mg
A label that names only the compound writes it like this. That figure is the whole salt, and the magnesium in it is about 60% of it.
Magnesium oxide ................................ 500 mg
Stacky does not convert between the two. We do not know which salt, which hydrate or which convention your brand used, and a guess would turn a figure you can check into one you cannot.
Published intake references for magnesium, the element
These figures are magnesium’s. They are here because magnesium oxide is a source of magnesium, not because any authority set them for magnesium oxide. Where the EU and the US disagree, both are shown; nothing is averaged, converted or reconciled. A tolerable upper intake level is the only kind of figure that sets a ceiling; a recommended or adequate intake is context, not a limit.
Applies to one chemical form only: readily dissociable magnesium salts (e.g. chloride, sulphate, aspartate, lactate) and compounds such as MgO EFSA →
Applies to one chemical form only: supplemental / pharmacological magnesium NIH ODS / IOM-DRI (NASEM) →
On the EU ceiling and this form. EFSA's upper limit names compounds such as MgO by formula. This is the one form on these pages the authority named itself.
Other forms of magnesium with a page
Indexed studies
A study reaches this page only if its own title names magnesium oxide or one of its recorded alternative names, and does not name a disease or clinical condition. Titles are the studies’ own words, newest first. A study appearing here is not a statement that magnesium oxide does what the study set out to look at. How this list is built →
| Title | Journal | Year | Reference |
|---|---|---|---|
| Effects of Magnesium Citrate, Magnesium Oxide, and Magnesium Sulfate Supplementation on Arterial Stiffness: A Randomized, Double-Blind, Placebo-Controlled Intervention Trial. | J Am Heart Assoc | 2022 | PubMed 35253448 |
Showing 1 of the 5 papers indexed against magnesium oxide in Stacky.
About this page
What this page does not contain: a figure of its own for magnesium oxide, a recommended dose, a grade, a conversion of any product’s amount, or any statement that it treats, prevents or improves a condition. How these pages are built →
Figures are read from the authorities’ published tables and can go out of date when those tables are revised. If one here is wrong, tell us at support@stacky-app.com and we will check it against the source.