Is elemental magnesium safe?

Elemental is a unit, not a form, which turns the question into one the guidance levels answer

Is elemental magnesium safe is a question that dissolves once its word is defined, because elemental magnesium is a unit rather than a product. On a supplement label, elemental magnesium means the magnesium content of whatever salt or chelate the capsule contains, the metal ion as opposed to the whole compound, so that 1500mg of magnesium bisglycinate is 300mg of elemental magnesium, 500mg of magnesium oxide is about 300mg, and 500mg of magnesium citrate is about 80mg, the label guide's elemental rule and the number the %NRV line is calculated from. Nobody swallows elemental magnesium in the chemical sense: magnesium metal is a reactive, inedible solid that burns with a white flame and is used in alloys and flares, and no supplement contains it, every supplement being a salt or a chelate that dissociates in the gut to release the ion, so a reader who has seen elemental magnesium on a label and wondered whether the element is safe to take has met the unit, not a form, and there is no product to be worried about. The question therefore becomes whether magnesium, at the elemental figure a label declares, is safe, and that is the question the safety levels are written to answer, because every level is expressed in elemental magnesium: the UK expert group's guidance of about 400mg a day from supplements, the EU's 250mg upper level set at the laxative threshold, the 375mg nutrient reference value, and the reference nutrient intakes of 300mg for men and 270mg for women, all elemental, all comparable directly with the elemental figure on a tub and none comparable with the compound weight on the front.

The safety of magnesium at the elemental figure, the two things the unit protects a reader from, and the question filed

The safety of magnesium at the elemental figure is the safety file the glycinate safety page sets out: a permitted form on the positive list, a toxicology that is osmotic, loose stools and diarrhoea at a surplus over the level, with no organ harm in working kidneys and hypermagnesaemia confined to impaired excretion or laxative-scale intake, a long-term record of trials at 300 to 500mg elemental for months without a safety signal, interactions that are spacing rules, and a short list of populations who ask first, kidney disease, myasthenia gravis, heart block, interacting medicines, pregnancy and minors, so that magnesium at 300mg elemental a day is safe for a healthy adult and daily use is what a maintenance nutrient assumes. The unit protects a reader from two errors that the safety question is usually hiding. Under-dosing: a tub declaring 500mg of magnesium citrate on the front delivers about 80mg elemental, a fifth of a reference-value dose, and a reader who took it for 500mg has taken 80, the %NRV line settling it. Over-counting the other way: a reader who fears 1500mg of bisglycinate is dangerous has confused the compound weight with the elemental figure, 1500mg of the compound being 300mg of the mineral and well under the level. The question filed: elemental magnesium is a unit, the magnesium content of a salt, and is safe in the only sense the question can mean, magnesium at the elemental figure within about 400mg supplemental a day in working kidneys, with the elemental figure being the number to compare against every level and the compound weight being the carrier, the worked example printing both, 1500mg bisglycinate giving 300mg elemental at 80% NRV, £19.99 for 90 days at 22p.

The verdict, a unit, and the mineral it measures safe within its level

Is elemental magnesium safe: elemental magnesium is a unit, the magnesium content of the salt or chelate in a capsule, and no supplement contains magnesium metal, so the question is whether magnesium at the elemental figure a label declares is safe, which it is, within the UK guidance level of about 400mg supplemental a day in working kidneys, with the osmotic laxative effect as the practical ceiling, every safety level written in elemental magnesium and the compound weight on the front being the carrier and not the number to compare. Both figures printed: Futuro Labs Magnesium Glycinate, 1500mg bisglycinate giving 300mg elemental at 80% NRV, £19.99 for 90 days at 22p a day.

What to check on the label

Questions people also ask

What does elemental magnesium mean on a supplement?

The magnesium content of the salt or chelate in the capsule, the metal ion as opposed to the whole compound: 1500mg of magnesium bisglycinate is 300mg of elemental magnesium, and the %NRV line is calculated from the elemental figure.

Is elemental magnesium the same as magnesium metal?

No: magnesium metal is a reactive, inedible solid used in alloys and flares and is in no supplement; elemental magnesium on a label is a unit for the mineral content of a salt that dissociates in the gut to release the ion.

How much elemental magnesium is safe per day?

Up to the UK guidance level of about 400mg a day from supplements for a healthy adult, with the osmotic laxative effect as the practical ceiling, harm only in failed kidneys, and 300mg elemental the section's standing dose.

Is 1500mg of magnesium bisglycinate dangerous?

No: 1500mg is the compound weight, about 300mg of elemental magnesium at the commercial 20% figure, well under the 400mg level, the confusion being between the carrier and the mineral.

Why do safety levels use elemental magnesium?

Because the mineral is what the body absorbs and the levels are set for: the UK guidance, the EU upper level, the NRV and the reference intakes are all elemental, so only the elemental figure on a tub compares with them.

Sources

1. The magnesium bisglycinate chemistry: the pure chelate, one magnesium to two glycine, is about 14% magnesium by weight, and commercial bisglycinate ingredients, buffered or of different chelate ratios, declare magnesium contents up to about 20%. PubMed record
2. Expert Group on Vitamins and Minerals. Safe Upper Levels for Vitamins and Minerals. Food Standards Agency, 2003 (magnesium guidance level 400mg a day from supplements). https://cot.food.gov.uk/sites/default/files/vitmin2003.pdf
3. The European Food Safety Authority's tolerable upper intake level for magnesium: 250mg a day from supplements, water and added sources, set at the threshold of the mild osmotic laxative effect rather than at a level of harm, and distinct from the UK expert group's guidance level of about 400mg. https://www.efsa.europa.eu/en/efsajournal/pub/4186
4. Retained Regulation (EU) No 1169/2011, Annex XIII: nutrient reference value for magnesium 375mg. https://www.legislation.gov.uk/eur/2011/1169/annex/XIII

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