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What Is Magnesium Glycinate? Dose, Side Effects, Who Should Avoid
Magnesium glycinate is magnesium bound to glycine, an amino acid, and it is the form most people are steered towards for daily use because it is absorbed well and, unlike citrate or oxide, rarely loosens the bowels. The magnesium in it does what magnesium does: it contributes to normal muscle function, normal functioning of the nervous system, normal psychological function, normal energy-yielding metabolism, the maintenance of normal bones and a reduction of tiredness and fatigue.1 The glycine is mostly a carrier; it is the same amino acid found in protein foods and it is what makes the compound gentle. The numbers on the label are where people go wrong. "Magnesium glycinate 1,000 mg" is roughly 100 to 140 mg of magnesium, because the glycine is most of the weight, and the figure to compare with the UK reference intake of 300 mg for men and 270 mg for women is the elemental one.2 This page covers what it is for, how much to take, the downsides, who should avoid it, and the questions people ask most.
- What it is: magnesium chelated to two glycine molecules; glycinate and bisglycinate are the same thing
- Best for: daily top-up of a diet short in magnesium, particularly if other forms upset your stomach
- Dose: 100 to 300 mg of elemental magnesium a day, within the UK guidance of 400 mg from supplements
- Downsides: cost, bulky capsules, and a minority who feel restless or sleep worse on it
- Avoid without advice: kidney disease; a heart rhythm condition; and space it from certain medicines
What magnesium glycinate actually is
Minerals cannot be swallowed on their own; they are bound to something. Magnesium oxide binds it to oxygen, citrate to citric acid, and glycinate to glycine, the simplest amino acid. Because two glycine molecules attach to each magnesium, the full name is magnesium bisglycinate; "glycinate" is the shorthand and the two names describe the same compound. The chelate holds together through the stomach and releases the magnesium in the small intestine, where glycine's own transport routes help uptake, which is the basis of the claim that it is well absorbed.3 One caution: some products labelled "glycinate" are "buffered", meaning magnesium oxide has been added to raise the elemental content cheaply. The label will say "magnesium bisglycinate and magnesium oxide" if so, and the oxide brings back the bowel effect the glycinate was chosen to avoid. Our hub on what magnesium is good for has the elemental content of every common form.
What does taking magnesium glycinate do?
It tops up magnesium, and the effects depend entirely on whether you were short. If you were, the signs of shortfall ease over two to four weeks: cramps and twitching, tiredness, a poor appetite, sometimes low mood. If you were not, nothing happens that you can feel, because the kidneys excrete what is not needed. The authorised roles above describe its contribution to normal function, not a treatment for anything. The questions people bring to this form specifically, sleep, anxiety, cramps, restless legs and migraine, have no authorised claim, and the evidence is set out honestly in does magnesium help you sleep: small trials in people who were low, a modest effect, nothing in people with normal status.4 Glycinate is not better than other forms for any of those; it is chosen for tolerability.
How much magnesium glycinate per day?
Read the elemental figure. A label saying "magnesium (as bisglycinate) 200 mg" means 200 mg of magnesium; a label saying "magnesium bisglycinate 1,200 mg" means about 240 mg of magnesium if it is a pure chelate, and you should find the elemental amount in the nutrition panel as a percentage of the 375 mg reference value. For a healthy adult topping up a diet, 100 to 300 mg of elemental magnesium a day is enough, and the UK guidance for supplements is to stay at or below 400 mg a day, above which loose stools become likely even with glycinate.2 There is no need to take the maximum; a dose that closes the gap between what you eat and 270 to 300 mg is the right one. Is it OK to take magnesium every day covers daily use and the signs of too much.
Night or morning?
Either. The mineral does not care, and no trial has compared timings. Evening suits people trying it for cramps or sleep and is when most remember; morning suits people who find it makes them restless. With food if it upsets your stomach, and separated by two to four hours from the medicines listed below. The one timing point with evidence is that absorption is slightly better from smaller doses, so splitting 300 mg into two is marginally more efficient than one capsule, though not enough to matter for most.
What is the downside of magnesium glycinate?
Price and bulk. Because glycine is most of the weight, a useful dose means large capsules or several of them, and the chelate costs more per milligram of magnesium than oxide or citrate.
Restlessness in a minority. A small number of people report feeling wired, anxious or sleeping worse after starting it, and forum threads on this are common enough to take seriously even though no trial has looked. Glycine itself is mildly stimulating for some. If it happens, move the dose to the morning or try a different form; if it persists, it is not for you.
Still laxative at high doses. Gentler than citrate and oxide, not immune. Above 400 mg a day, or in a blend that includes citrate, loose stools return.
It can hide the real problem. Cramps, palpitations and tiredness have many causes; a supplement taken instead of a GP visit delays the diagnosis.
Who should avoid magnesium glycinate?
Kidney disease. The kidneys clear magnesium; if they are not working well it accumulates, and excess magnesium causes low blood pressure, a slow or irregular heartbeat, weakness and confusion.5 Do not take any magnesium supplement without your renal team's advice.
Heart rhythm conditions. Magnesium is sometimes prescribed and sometimes unsuitable; ask your cardiologist or pharmacist first.
Myasthenia gravis, where magnesium can worsen weakness.
Bowel conditions with diarrhoea, including colitis, where glycinate is the gentlest form but any magnesium can worsen symptoms; a GP or dietitian question rather than a self-care one.
Pregnancy and breastfeeding: food sources first, and a supplement within the guidance only with your midwife's agreement.
Medicines to separate from magnesium glycinate
Magnesium binds some medicines in the gut and reduces their absorption: tetracycline and quinolone antibiotics, bisphosphonates for bone density, and levothyroxine. Take those two hours before or four to six hours after the magnesium. Two groups of medicines lower magnesium over time and may be a reason to take it: proton pump inhibitors such as omeprazole after a year or more, and loop and thiazide diuretics.5 Painkillers such as tramadol, antidepressants and anti-epileptics such as lamotrigine have no established interaction with magnesium, but every question about mixing a prescription medicine with a supplement belongs with your pharmacist, who has your full list. What you should not take with magnesium has the full list.
Glycinate or something else?
Glycinate for daily use and sensitive stomachs. Citrate if constipation is part of why you want magnesium, since its laxative effect is the point. Oxide only as a cheap laxative. Malate as an alternative to glycinate. Threonate and taurate are sold on specific stories with thin human evidence and high prices. Which magnesium is best compares them. Food remains the cheapest route: a handful of pumpkin seeds a day supplies about 160 mg, and which foods contain magnesium lists the rest.
Wellgard's Mag 1200 magnesium bisglycinate is a pure chelate, not buffered with oxide, with the elemental magnesium stated per serving; magnesium contributes to normal muscle function, normal functioning of the nervous system, normal psychological function, the maintenance of normal bones and a reduction of tiredness and fatigue.
What we don't know
- How much better absorbed glycinate is than other forms in people. Studies are small and mostly compare oxide and citrate.3
- Why a minority feel restless on it. Reported widely, unstudied.
- Whether glycine at these doses does anything itself. Probably not; a 300 mg dose carries about 2 g of glycine against a dietary intake of several grams.
Frequently asked questions
What is magnesium glycinate best for?
Daily top-up of a diet short in magnesium, in people who want the gentlest form on the bowels. It is not better than other forms for sleep, cramps or mood; those have no authorised claim.1, 4
Is magnesium glycinate the same as bisglycinate?
Yes. Two glycine molecules bind each magnesium, so bisglycinate is the full name and glycinate the shorthand.
What happens if you take magnesium glycinate every day?
If you were short, cramps, twitching and tiredness ease over weeks. If you were not, nothing noticeable; excess is excreted. Keep to 400 mg of elemental magnesium or less.2
Can I take magnesium glycinate with lamotrigine or tramadol?
No interaction is established with either, but ask your pharmacist, who knows your full prescription list, rather than relying on a general answer.
Can I take magnesium if I have colitis?
Ask your GP or IBD team. Glycinate is the gentlest form, but any magnesium can worsen diarrhoea during a flare.
Sources
- NHS. Vitamins and minerals: others, including magnesium. nhs.uk; Great Britain nutrition and health claims register.
- Costello R, et al. Perspective: call for re-evaluation of the tolerable upper intake level for magnesium supplementation in adults. Advances in Nutrition, 2023. PubMed 37487817.
- Pajuelo D, et al. Comparative clinical study on magnesium absorption and side effects after oral intake of microencapsulated magnesium and other forms. Nutrients, 2024. PubMed 39770988.
- Mah J, Pitre T. Oral magnesium supplementation for insomnia in older adults: a systematic review and meta-analysis. BMC Complementary Medicine and Therapies, 2021. PubMed 33865376.
- Liamis G, et al. An overview of diagnosis and management of drug-induced hypomagnesemia. Pharmacology Research and Perspectives, 2021. PubMed 34278747.
This article is general information, not medical advice. If you have kidney disease, a heart rhythm condition or take prescription medicines, ask your pharmacist or GP before taking magnesium.
