Magnesium Glycinate: What It Is, How Much to Take, and When
Magnesium glycinate, also sold as magnesium bisglycinate, is magnesium bound to the amino acid glycine, a chelated form of the mineral used in food supplements. To compare products, read the milligrams of magnesium per serving rather than the weight of the glycinate, and check the label says fully reacted with no magnesium oxide.
A plain-English guide to magnesium glycinate, also sold as magnesium bisglycinate: what the form is, how to read the magnesium figure on a label, how much UK adults need a day, how it compares with citrate and oxide, and when to take it.
- Magnesium glycinate is magnesium bound to the amino acid glycine. Magnesium bisglycinate is the same thing: the name counts the two glycine molecules.
- Buffered means glycinate blended with another form, usually magnesium oxide. Fully reacted means all of it is glycinate.
- Read the magnesium figure on the label, not the weight of the compound. 1,667mg of magnesium bisglycinate provides 200mg of magnesium.
- UK adults need about 300mg (men) and 270mg (women) of magnesium a day from all sources. The figure used on labels, the NRV, is 375mg. The NHS says 400mg or less a day from supplements is unlikely to cause any harm.
- Magnesium contributes to a reduction of tiredness and fatigue, to normal functioning of the nervous system, to normal psychological function and to normal muscle function.
- There is no single right time of day. Taking it every day matters more, so pick a time you will keep to, such as the evening.
What is magnesium glycinate?
Magnesium glycinate is a form of magnesium in which the mineral is bound to glycine, an amino acid. Bound like this, the compound is called a chelate, and it is one of several forms of magnesium sold as supplements, alongside citrate, oxide, malate and others.
On a label you may see it called magnesium glycinate, magnesium bisglycinate or magnesium diglycinate. You may also see the words "fully reacted" or "buffered", which tell you whether the product is only glycinate or a blend. Both are explained below.
Is magnesium glycinate the same as bisglycinate?
Yes. Magnesium bisglycinate and magnesium glycinate are two names for the same compound. "Bis" means two: each magnesium atom is bound to two molecules of glycine. Glycinate is the shorter, everyday name, and bisglycinate is the more exact chemical one.
So a product labelled "magnesium bisglycinate" and one labelled "magnesium glycinate" can contain the same ingredient. The differences that matter between products are how much magnesium each serving gives, whether the glycinate is fully reacted or buffered, and what else is in the capsule.
What is buffered magnesium glycinate?
Buffered magnesium glycinate is magnesium glycinate blended with another form of magnesium, usually magnesium oxide. Oxide carries more magnesium per milligram and costs less, so a buffered product can show a higher magnesium figure for a lower price, but it is no longer only glycinate.
"Fully reacted" means the opposite: all of the magnesium has been bound to glycine. A buffered product is not wrong, it is simply a different product. If you want glycinate only, check two places: the front of the pack for the words "buffered" or "fully reacted", and the ingredients list for "magnesium oxide". Some labels say neither, and then the ingredients list is the one to trust.
How much magnesium is in magnesium glycinate?
Magnesium is only a small part of the compound's weight, because glycine makes up most of it. In ours, 1,667mg of magnesium bisglycinate provides 200mg of magnesium, about 12% by weight, so the figure to compare between products is the magnesium itself, often shown as "of which magnesium" or "elemental magnesium".
This is the most common source of confusion when comparing labels. A front label that says "1,000mg magnesium glycinate" describes the weight of the compound, which gives roughly 120mg of magnesium. A label that says "200mg magnesium" describes the mineral itself. Check the nutrition table to see which one you are reading.
The key idea: compare products on milligrams of magnesium per serving, not on the weight of the glycinate.
How much magnesium do you need a day?
The NHS says adults aged 19 to 64 need about 300mg of magnesium a day for men and 270mg a day for women, and that most people can get this from a varied diet. If you take a supplement, the NHS says 400mg or less a day of magnesium from supplements is unlikely to cause any harm.1
| Figure | Amount a day | What it is |
|---|---|---|
| Men, 19 to 64 | 300mg | NHS daily amount, from all sources1 |
| Women, 19 to 64 | 270mg | NHS daily amount, from all sources1 |
| NRV (Nutrient Reference Value) | 375mg | The reference used for the "% NRV" figure on food and supplement labels5 |
| From supplements | 400mg or less | The NHS says this is unlikely to cause any harm1 |
Scroll the table sideways on mobile to see all columns.
Magnesium is found in a wide variety of foods, including spinach, nuts and wholemeal bread.1 A supplement adds to what you already eat, so the amount it provides does not have to match the daily figures on its own. Two capsules of our Magnesium Glycinate provide 200mg of magnesium, 53% of the NRV, which sits under the NHS figure for supplements.
For readily absorbed magnesium salts taken as supplements, the EU's Scientific Committee on Food set an upper level of 250mg a day for adults, based on mild, temporary loose stools seen at higher intakes.4 That level does not include the magnesium in ordinary food.
Magnesium oxide vs glycinate vs citrate: what is the difference?
They are different compounds that all supply magnesium. Oxide packs the most magnesium into each milligram and costs the least, citrate is magnesium bound to citric acid, and glycinate is magnesium bound to the amino acid glycine.
| Form | What it is bound to | Worth knowing |
|---|---|---|
| Magnesium glycinate (bisglycinate) | Glycine, an amino acid | Lower magnesium per milligram of compound, so capsules are larger or you take two. Check that it is fully reacted, not buffered with oxide. |
| Magnesium citrate | Citric acid | A widely used organic salt that dissolves well in water. Often sold as a powder or tablet. |
| Magnesium oxide | Oxygen | The highest magnesium content by weight and the lowest cost. It dissolves poorly in water. |
Scroll the table sideways on mobile to see all columns.
Studies on how well each form is absorbed are few and small. In one often-quoted study, magnesium oxide was absorbed far less than magnesium chloride, lactate or aspartate.3 Glycinate was not part of that study, so we do not quote a figure for it. The fair way to compare forms is the magnesium per serving, the rest of the formula, and the price for the same amount of magnesium. What we can say plainly is what is in ours: pure, fully reacted magnesium bisglycinate, with no magnesium oxide.
What does magnesium do?
Magnesium is an essential mineral involved in many processes in the body. In the UK only authorised wording may be used to describe what a nutrient does, and these four are among the claims authorised for magnesium.6
The register also lists these for magnesium: it contributes to normal energy-yielding metabolism, to electrolyte balance, to normal protein synthesis, to the maintenance of normal bones and to the maintenance of normal teeth, and it has a role in the process of cell division.6 The claims apply to a product that gives at least 15% of the NRV per serving. Our two capsules give 53%.
When to take magnesium glycinate: morning or evening?
You can take magnesium at any time of day, with or without food. There is no strong evidence that one time is better than another, so the best time is the one you will keep to every day.
Many people find the evening easiest to remember, with a glass of water after their evening meal. Our Magnesium Glycinate is made to be taken in the evening, two capsules with water, which is why its name carries "Night Time". If you also take a B complex, a simple routine is the B complex with breakfast and magnesium in the evening. If a supplement ever upsets your stomach, taking it with food or splitting the dose can help. Always follow the label and do not exceed the stated dose.
How to read a magnesium glycinate label
Check five things: the magnesium per serving, the words fully reacted or buffered, whether magnesium oxide is in the ingredients, how short the ingredients list is, and the price for the same amount of magnesium.
- Magnesium per serving. Find the "of which magnesium" line in the nutrition table and note how many capsules make a serving.
- Fully reacted or buffered. Fully reacted means all of it is glycinate. Buffered means part of it is another form.
- Magnesium oxide. If you want glycinate only, oxide should not appear in the ingredients list.
- Everything else in the capsule. Fillers, flow agents and the capsule shell are all listed. Gelatine capsules are not vegan.
- Price per 200mg of magnesium. Divide the price by the total magnesium in the bottle, then multiply by 200.
Read the same way, our label says: 200mg of magnesium (53% NRV) from 1,667mg of pure, fully reacted magnesium bisglycinate per two capsules; not buffered and no magnesium oxide; a plant cellulose (HPMC) capsule; no fillers and no flow agents. It is made in Britain at a site certified to GMP and FSSC 22000 (food safety, built on ISO 22000 and HACCP). Our price check works out the cost per 200mg of magnesium for UK products made to the same spec.
Who should check first?
Speak to your doctor or pharmacist before taking magnesium if you have kidney problems, take regular medication, or are pregnant or breastfeeding. Magnesium can affect how some medicines are absorbed, such as certain antibiotics and bone medicines, so the timing of doses may need to be spaced apart.
Food supplements should not replace a varied, balanced diet and a healthy lifestyle. Keep them out of the reach of young children.
Frequently asked questions
What is magnesium glycinate?
Magnesium glycinate is magnesium bound to the amino acid glycine, a chelated form of the mineral used in food supplements. It is also sold as magnesium bisglycinate. When comparing products, read the milligrams of magnesium per serving, not the weight of the glycinate.
Is magnesium glycinate the same as magnesium bisglycinate?
Yes. They are two names for the same compound: magnesium bound to two molecules of the amino acid glycine. Bisglycinate is the more exact chemical name, glycinate the everyday one.
What does buffered magnesium glycinate mean?
Buffered means magnesium glycinate has been blended with another form of magnesium, usually magnesium oxide, which raises the magnesium figure at a lower cost. Fully reacted means all of the magnesium is bound to glycine. Ours is fully reacted and not buffered, with no magnesium oxide.
What is the difference between magnesium oxide and magnesium glycinate?
They are different compounds. Magnesium oxide has the most magnesium per milligram, costs the least and dissolves poorly in water. Magnesium glycinate is magnesium bound to glycine, so it has less magnesium per milligram and needs larger capsules or two of them. Compare them on magnesium per serving and price for the same amount of magnesium.
How much magnesium glycinate should I take a day?
Go by the magnesium figure, not the weight of the glycinate. The NHS says adults need about 300mg (men) or 270mg (women) of magnesium a day from all sources, and that 400mg or less a day from supplements is unlikely to cause any harm. Two capsules of ours provide 200mg of magnesium. Follow the label and do not exceed the stated dose.
Is it better to take magnesium in the morning or the evening?
Either is fine. There is no strong evidence that one time is better, so choose a time you will keep to every day. Ours is made to be taken in the evening, two capsules with water.
Can I take magnesium glycinate every day?
Yes, magnesium supplements are designed for daily use. Stay within the dose on the label. If you have kidney problems, take medication, or are pregnant or breastfeeding, check with your doctor or pharmacist first.
Is magnesium glycinate vegan?
The ingredient itself can be, but check the capsule: some use gelatine. Ours uses a plant cellulose (HPMC) capsule and is suitable for vegans.
