How Much Elemental Magnesium Is in Magnesium Glycinate?

Magnesium bisglycinate, usually sold as magnesium glycinate, is about 14% magnesium by weight, so 1,000 mg of the compound provides roughly 140 mg of elemental magnesium. The elemental figure is the one to compare between products, because it tells you how much magnesium you actually get, whatever form it is bound to.

What 'elemental magnesium' means

Magnesium in a supplement is never on its own. It is always bound to another molecule, such as glycine, citrate or oxide, to make a stable compound that can be put into a capsule. The total weight of that compound includes both the magnesium and the molecule it is attached to.

Elemental magnesium is the weight of the magnesium alone. It is the figure that counts towards your daily intake and the figure used for the percentage of the Nutrient Reference Value (NRV) on a UK label. The adult NRV for magnesium is 375 mg a day, set out in Annex XIII of the retained food information regulation: legislation.gov.uk.

This is why two labels can look very different and still describe a similar amount. One might say '1,000 mg magnesium glycinate' and another '140 mg magnesium'. The first is the compound, the second is the elemental amount.

Why glycinate carries less magnesium per milligram

In magnesium bisglycinate, one magnesium atom is bound to two molecules of glycine, an amino acid. Glycine is much heavier than magnesium, so it makes up most of the compound's weight. Calculated from molecular weights, anhydrous magnesium bisglycinate is about 14% magnesium.

For comparison, the same calculation gives about 60% for magnesium oxide and about 16% for anhydrous magnesium citrate. Hydrated forms, which hold water in the crystal, carry a little less magnesium per gram. These are chemistry figures, not a ranking: the percentage only tells you how much powder is needed to reach a given elemental amount.

That is the main reason glycinate products often use two or three capsules for a daily serving. There is simply more compound to fit in.

Buffered and fully reacted products

Some products sold as magnesium glycinate are 'buffered'. This means another form, usually magnesium oxide, has been blended in to raise the amount of magnesium per capsule. It is a legitimate approach, but it means the product is not only glycinate.

A 'fully reacted' product contains the chelate alone. If you want a single form, check the ingredient list. Anything other than magnesium bisglycinate listed as a magnesium source tells you it is a blend.

If the label gives a compound weight and an elemental weight, you can divide one by the other. A result far above 14% suggests a denser form has been added.

How to read a magnesium glycinate label

Find the line that states magnesium with a %NRV next to it. That is the elemental amount. The compound weight, if it is shown, usually appears in the ingredients list and will be higher.

Check how many capsules the figure refers to. An amount per daily serving of three capsules is not the same as per capsule, and products can differ here.

Consider your total intake. The NHS says that taking 400 mg or less a day of magnesium from supplements is unlikely to cause any harm, and that high doses for a short time can cause diarrhoea: NHS. The European Food Safety Authority uses a lower tolerable upper level of 250 mg a day for readily dissociable magnesium salts added to foods and supplements, set out in its summary of tolerable upper intake levels: EFSA.

Our step-by-step guide covers the rest of a supplement label.

Read our guide to reading supplement labels.

Food sources

Food is the main source of magnesium for most people. The NHS lists spinach, nuts and wholemeal bread as good sources, and other leafy greens, seeds, beans and wholegrains also contribute. The NHS says most people should be able to get the magnesium they need from a varied and balanced diet.

A supplement sits alongside food. When you add up your intake, only the supplement counts towards the supplemental guidance figures above.

Hyoomen's figures

Hyoomen Magnesium Glycinate states 225 mg of elemental magnesium per 3 capsules, from magnesium bisglycinate.

See Hyoomen Magnesium Glycinate.

For more on why the form is named on the label, read our guide to chelated magnesium.

Read: chelated magnesium explained.

Frequently asked questions

Is magnesium glycinate the same as magnesium bisglycinate?

Yes. In everyday labelling the two names describe the same compound: magnesium bound to two glycine molecules.

Does the compound weight count towards my daily intake?

No. Only the elemental magnesium counts towards the NRV and the supplement guidance figures.

Why do I need more than one capsule?

Glycinate is bulky. Reaching a useful elemental amount takes more powder than denser forms such as oxide.

Should I take magnesium with medicines?

Magnesium can affect the absorption of some medicines, including certain antibiotics. Ask a pharmacist about timing.

Important

This article is general information, not medical advice. Food supplements should not be used as a substitute for a varied, balanced diet and a healthy lifestyle. If you are pregnant, breastfeeding, taking any medication or under medical supervision, speak to your GP or pharmacist before taking a supplement. Do not exceed the stated recommended daily dose.