Magnesium
Mg · last AI check: 2026-07-19
In short
Takes part in many processes within cells. Found in nuts, wholegrains and legumes.
What it does in the body
The sentences below are officially authorised EU health claims.
Magnesium contributes to a reduction of tiredness and fatigue EU health claim
Commission Regulation (EU) No 432/2012 of 16 May 2012, Annex — list of permitted health claims · register entry: 244 · EFSA opinion: 2010;8(10):1807
Condition of use on a product: The product is at least a source of Magnesium.
Magnesium contributes to normal muscle function EU health claim
Commission Regulation (EU) No 432/2012 of 16 May 2012, Annex — list of permitted health claims · register entry: 241, 380, 3083 · EFSA opinion: 2009;7(9):1216; 2010;8(10):1807
Condition of use on a product: The product is at least a source of Magnesium.
How much you need
| Country / organisation | Group | Value | Type |
|---|---|---|---|
| EFSA | adult men | AI Adequate intake — an approximate value used when data are insufficient to set an exact requirement (RDA). | |
| FAO | adult men | RNI Reference nutrient intake — the RDA equivalent in WHO/FAO, UK and Philippine terminology. | |
| NASEM (US/CA) | adult men | RDA Recommended daily allowance — covers the needs of almost all healthy people in a group. | |
| Philippines | adult men | RNI Reference nutrient intake — the RDA equivalent in WHO/FAO, UK and Philippine terminology. | |
| India | adult men | RDA Recommended daily allowance — covers the needs of almost all healthy people in a group. | |
| Poland | adult men | RDA Recommended daily allowance — covers the needs of almost all healthy people in a group. | |
| Switzerland | adult men | RDA Recommended daily allowance — covers the needs of almost all healthy people in a group. | |
| United Kingdom | adult men | RNI Reference nutrient intake — the RDA equivalent in WHO/FAO, UK and Philippine terminology. |
Reference values from different countries are not directly comparable — they differ in definition and age group. How to read reference values →
Every value states its source — click it to see the document, location and link.Data and content are prepared and cross-checked against source documents by several independent AI models. They have not been audited by a human editor.Before citing a value, check it in the source document — verification is automated (AI), not editorial.
Worth knowing
Magnesium is a cofactor for hundreds of enzymatic reactions, including all those involving ATP — the cell's energy molecule binds magnesium in order to be used at all. This is why magnesium comes up in the context of muscle function, the nervous system and energy metabolism all at once.
Why a blood test tells you less than it seems
Only a small part of the body's magnesium circulates in the blood — the great majority is found in bone and inside cells. The body keeps the serum concentration within a narrow range, drawing on bone reserves when needed. The practical consequence is that a normal serum magnesium result doesn't rule out tissue deficiency, and the test itself has limited value as a screening tool. Interpretation is for a doctor.
Forms in supplements differ in absorption
Magnesium in supplements comes in the form of a salt — some dissolve well, others poorly, and the stated mass of the preparation isn't the same as the content of the element itself. The same number of milligrams on the packaging can therefore mean a different amount of available magnesium, depending on the chemical form. When comparing supplements, look for the magnesium ion content, not the mass of the salt.
It's also worth knowing that excess magnesium from supplements most often shows up as a laxative effect — unabsorbed magnesium stays in the gut and binds water. This is one of the reasons why the upper limit for magnesium applies to doses from supplements, not to magnesium from food.
Where to find it
nuts · wholegrains · legumes · cocoa · green vegetables
This material is for information and education. It does not replace advice from a doctor or dietitian. For health matters, consult a qualified medical professional.