Magnesium glycinate: what it is, what it’s good for and when to take it

What is magnesium glycinate?

Magnesium is a mineral your body needs every day but can’t make for itself, so it has to come from food or, if you choose, a supplement. In a capsule or tablet, magnesium is always bound to something else, and that partner gives the form its name. In magnesium glycinate, the partner is glycine – the smallest of the amino acids.

When each magnesium atom is bound to two glycine molecules, it’s called magnesium bisglycinate. On UK shop shelves and labels the two names are used for the same thing, and you’ll sometimes see “magnesium diglycinate” too.

What is magnesium glycinate good for?

The benefits come from the magnesium, not from the form it’s bound to. Under the authorised health claims on the Great Britain nutrition and health claims register, magnesium contributes to:

• a reduction of tiredness and fatigue
• normal muscle function
• normal functioning of the nervous system
• normal psychological function
• electrolyte balance
• normal energy-yielding metabolism
• the maintenance of normal bones and teeth
• normal protein synthesis

What sets glycinate apart from other forms is how well it’s absorbed and how kind it tends to be on the gut – not what the magnesium does once it’s in your body. You’ll see glycinate sold online as the form for sleep, stress or anxiety. None of those are authorised health claims in the UK, and the research on magnesium and sleep is limited.

Is magnesium glycinate better than other forms of magnesium?

Every form delivers the same mineral. They differ in how much magnesium they carry per gram, how well they’re absorbed and how your stomach reacts.

Organic forms such as glycinate and citrate are generally absorbed a little better than magnesium oxide, although how much difference that makes in practice isn’t clear. There’s no single form that’s best for everyone – choose on how your stomach copes, how many capsules you’re happy to take and the cost per daily dose. We compare more forms in Types of magnesium: which form is best?

When should you take magnesium glycinate?

No time of day has been shown to work best. Plenty of people take magnesium in the evening as part of their routine; others take it with breakfast. What matters is taking it regularly.

• Take it with a meal if you have a sensitive stomach.
• Split the daily dose between morning and evening if taking it all at once upsets your stomach.
• Stick to the dose on the label.

There’s more detail in When is the best time to take magnesium?

How much magnesium glycinate should I take?

In the UK, the NHS says adults aged 19 to 64 need 300 mg of magnesium a day for men and 270 mg a day for women, and that you should be able to get all you need from a varied and balanced diet. Good sources include nuts, seeds, wholemeal bread, spinach, beans and brown rice.

For supplements, the NHS advises that 400 mg or less a day from supplements is unlikely to cause any harm. The European Food Safety Authority sets a lower tolerable upper level of 250 mg a day of magnesium from supplements for adults and children from 4 years, because higher amounts can cause diarrhoea. We use the stricter 250 mg figure. Neither limit includes the magnesium in ordinary food.

See the best food sources in Magnesium-rich foods, and the full breakdown by age in How much magnesium do you need per day?

What are the side effects of magnesium glycinate?

Taken at the dose on the label, magnesium is considered safe for healthy adults – your kidneys clear any excess. The most common side effects are loose stools or diarrhoea, usually at higher doses, and sometimes nausea or stomach cramps. Glycinate tends to cause fewer of these problems than oxide or citrate.

If it doesn’t agree with you, take it with food, split the dose or cut back. If you have kidney problems, speak to your GP before taking any magnesium supplement.

Who should not take magnesium glycinate?

Most healthy adults can take magnesium at the recommended dose. Talk to your GP or pharmacist first if any of these apply to you:

• You have kidney disease or reduced kidney function. Your kidneys get rid of excess magnesium; if they’re not working well, it can build up in the body.
• You take medicines regularly – for example certain antibiotics, bisphosphonates for osteoporosis such as alendronic acid, levothyroxine for an underactive thyroid, or diuretics (water tablets).
• You have a heart condition or take medicine for high blood pressure. Some of these medicines, such as diuretics (water tablets), can change your magnesium levels.
• You’re pregnant or breastfeeding. Speak to your midwife, GP or pharmacist before starting any supplement.

Adult magnesium supplements aren’t meant for children. Ours is not suitable for under-18s, and children normally get enough magnesium from food.

What should you not take with magnesium glycinate?

Magnesium can bind to some medicines in the gut so less of them is absorbed. That includes some antibiotics (tetracyclines such as doxycycline, and quinolones such as ciprofloxacin), bisphosphonates such as alendronic acid, and levothyroxine. Usually leaving a gap of a few hours between them is enough.

If you take any medicine regularly, ask your pharmacist how best to space it with a magnesium supplement – they can check against your own prescriptions.

Who might benefit from a magnesium supplement?

Food comes first. A supplement can be a way to top up if your intake is low – and in the UK that isn’t rare. The National Diet and Nutrition Survey (2016 to 2019) found that around 1 in 9 adults, and nearly half of girls aged 11 to 18, have magnesium intakes below the lower reference nutrient intake, the level that is likely to be too low for most people.

Some medicines, such as diuretics and proton pump inhibitors like omeprazole, can also lower magnesium levels when taken long term – usually over a year or more in the case of proton pump inhibitors. If you think you might be low, speak to your GP rather than guessing. Food supplements shouldn’t replace a varied, balanced diet and a healthy lifestyle.

How do I choose the best magnesium glycinate?

There’s no single best magnesium glycinate, and online round-ups weigh price, taste and dose in very different ways. Here’s what actually separates one product from another:

• Look at the amount of magnesium per daily dose, not the amount of magnesium glycinate.
• Read the ingredients list. Some products sold as glycinate also contain other forms, such as oxide – it should say so there.
• Work out the cost per daily dose rather than per tub.
• Stay at or below 250 mg of magnesium a day from supplements unless your GP has advised otherwise.
• Check what the capsule is made of if you’re vegan – gelatine capsules aren’t.

Our own magnesium is a three-form complex: 130 mg of magnesium from bisglycinate, 60 mg from citrate and 60 mg from malate – 250 mg of magnesium in a daily dose of two vegan capsules, plus 5 mg of vitamin B6. Vitamin B6 contributes to a reduction of tiredness and fatigue and to normal functioning of the nervous system.

4 HIM & HERMagnesium GlycinateThree magnesium forms – bisglycinate, citrate & malateView product →