Types of magnesium compared, and which is best

A useful rule of thumb with magnesium is that the form changes two things. It changes how much magnesium each capsule holds, and how well your body absorbs it.

No single type of magnesium is best for everyone. Citrate is well studied for absorption and beat oxide in trials lasting 60 days and 24 weeks [1][2]. Glycinate gave a small sleep benefit in one 2025 trial [3]. Oxide holds the most magnesium per capsule but is absorbed less well [4]. Whichever form you choose, the label tells you how much magnesium you actually get each day.

What are the different types of magnesium?

Supplement magnesium comes joined to another substance, which adds weight but no magnesium. UK law lists the forms supplements can use, including bisglycinate, citrate, malate, oxide, taurate and L-threonate [5].

Which type of magnesium is absorbed best?

Citrate, on the evidence so far Moderate. A 2025 systematic review of 14 magnesium studies in healthy adults found oxide was absorbed less well in 7 of the 8 trials that tested it against other forms [4].

Two longer trials compared forms head to head. Over 60 days in 46 healthy adults, citrate gave the highest blood magnesium, and both citrate and an amino-acid chelate beat oxide [1]. Over 24 weeks in 164 adults aged 45 to 75, citrate raised the magnesium passed in urine, a sign of how much was absorbed, more than oxide did. That trial was funded by a magnesium producer [2].

Glycinate has barely been tested against other forms. The 2025 review found no glycinate study that met its criteria [4]. A single-dose study of 40 adults found no clear difference between glycinate, citrate and oxide over 6 hours, and it was run by the maker of a rival product [9].

How you take it matters too. A 2017 review concluded that the type of salt matters less than often thought, and that several smaller doses a day are absorbed better than one large one [10]. Our library of magnesium studies lists the trials in people. In practice, a well-absorbed form you'll take every day is a sensible place to start.

Which magnesium is best for you?

It depends on what you want it for. Here are the forms ranked by goal, with the evidence for each.

Most of these rows rest on one or two trials, so treat the table as a starting point. The threonate trial was funded by a company behind the ingredient, and in the UK threonate is only authorised in supplements for adults, giving up to 250 mg of magnesium a day [11][13].

If your stomach is sensitive, our guide to magnesium side effects covers what helps. If you're looking at magnesium for constipation, our guides to magnesium oxide and citrate cover what the trials found.

How much magnesium is in each type?

Less than the big number on the front of the pack suggests. What counts is the magnesium itself, sometimes called elemental magnesium.

Take a 500 mg capsule of magnesium glycinate. Glycinate is about 14% magnesium, so that capsule holds roughly 70 mg of magnesium (about 19% of the daily reference amount). The same 500 mg of oxide holds about 300 mg [2][6][14].

UK labels must give the amount of magnesium per daily dose in milligrams, and as a percentage of the reference amount, which is 375 mg [5][14]. In practice, read that line rather than the weight of the compound in the ingredients.

The NHS says adults need about 300 mg a day for men and 270 mg for women, and that a varied diet should provide it. Taking 400 mg or less a day from supplements is unlikely to cause harm, while more than 400 mg for a short time can cause diarrhoea [15].

Which magnesium is best for sleep?

Glycinate has one encouraging trial, but the evidence is thin Early. In 155 adults with poor sleep, 250 mg of magnesium a day as bisglycinate for 4 weeks improved insomnia scores a little more than a placebo did, by 3.9 points against 2.3 [3].

In an older trial of 100 adults over 51, magnesium citrate did no better than a placebo for sleep [16]. We found no trial that compares forms head to head for sleep. Our guide to magnesium for sleep covers the trials in more detail.

Choosing the best magnesium supplement in the UK

We don't rank brands. These checks work on any label.

1. Find the magnesium figure. Look for the milligrams of magnesium per daily dose and the percentage of the reference amount [5].
2. Check the form. The ingredients should name it, such as magnesium bisglycinate or magnesium citrate. A "buffered" glycinate may be blended with oxide [7].
3. Add up your daily total. Keep magnesium from all your supplements at 400 mg a day or less, in line with the NHS [15].
4. Consider splitting it. Smaller doses spread through the day are absorbed better than one large dose [10].
5. Ask about testing. In a Polish study of 116 magnesium supplements, 58.7% fell outside the official range for the magnesium stated on the label [17]. So it's fair to ask a seller for test results.
6. Be wary of sleep promises. UK rules allow 10 health claims for magnesium, such as reducing tiredness and fatigue, and none of them is about sleep [18].

Where Nooroots fits

Nooroots Triple Magnesium is a food supplement with magnesium glycinate, citrate and malate, in three capsules a day. Magnesium contributes to normal psychological function and to a reduction of tiredness and fatigue [18].

Frequently asked questions

What is the best type of magnesium to take?

There's no single best type. Citrate beat oxide for absorption in longer trials, glycinate gave a small sleep benefit in one trial, and oxide holds the most magnesium per capsule but is absorbed less well [1][3][4].

Which magnesium is best for absorption?

Citrate, on current evidence. It beat oxide in trials lasting 60 days and 24 weeks, while glycinate, malate and threonate have barely been compared with other forms [1][2][4].

Can you take different types of magnesium together?

Yes, and some supplements combine two or three forms. Add up the magnesium from all of them and keep the total from supplements at 400 mg a day or less, in line with the NHS [15].

Is magnesium glycinate better than citrate?

Not clearly. Citrate has more absorption data and glycinate has a recent sleep trial, but few studies compare the two directly [1][3]. Our glycinate vs citrate guide compares them in detail.

Which magnesium is best for women?

We found no trial showing that one form suits women better than another. The NHS says women aged 19 to 64 need about 270 mg a day [15]. Our magnesium for women guide covers it in more detail.

Which magnesium is best for leg cramps?

None stands out. A Cochrane review found magnesium unlikely to prevent muscle cramps in older adults [12]. Our magnesium for cramps guide covers what else helps.

Read more about daily amounts in our guide to how much magnesium you need per day.

References

Every source here is listed so you can read it yourself. This guide is for general information and doesn't replace advice from your GP. We check it again at least every six months.

1. Walker AF, Marakis G, Christie S, Byng M (2003). Mg citrate found more bioavailable than other Mg preparations in a randomised, double-blind study. Magnesium Research 16(3): 183-91. PMID 14596323
2. Schutten JC, Joris PJ, Groendijk I, Eelderink C, Groothof D, van der Veen Y et al. (2022). Effects of Magnesium Citrate, Magnesium Oxide, and Magnesium Sulfate Supplementation on Arterial Stiffness: A Randomized, Double-Blind, Placebo-Controlled Intervention Trial. Journal of the American Heart Association 11(6): e021783. PMID 35253448
3. Schuster J, Cycelskij I, Lopresti A, Hahn A (2025). Magnesium Bisglycinate Supplementation in Healthy Adults Reporting Poor Sleep: A Randomized, Placebo-Controlled Trial. Nature and Science of Sleep 17: 2027-2040. PMID 40918053
4. Merschmann R, Burgmer C, Eckert GP, Wagner AE (2025). Bioavailability of Magnesium and Potassium Salts Used as Potential Substitutes for Sodium Chloride in Human Nutrition - A Review. Molecular Nutrition & Food Research 69(22): e70227. PMID 40931546
5. The Food Supplements (England) Regulations 2003 (SI 2003/1387), regulations 5 and 6 and Schedule 2, as amended. Accessed 31 October 2026. legislation.gov.uk
6. National Center for Biotechnology Information. PubChem compound summary for CID 84645, magnesium glycinate. Accessed 31 October 2026. pubchem.ncbi.nlm.nih.gov
7. Younes M, Aggett P, Aguilar F, Crebelli R, Dusemund B, Filipič M et al. (2018). Evaluation of di-magnesium malate, used as a novel food ingredient and as a source of magnesium in foods for the general population, food supplements, total diet replacement for weight control and food for special medical purposes. EFSA Journal 16(6): e05292. PMID 32625931
8. Turck D, Bohn T, Castenmiller J, De Henauw S, Hirsch-Ernst KI, Maciuk A et al. (2024). Safety of magnesium l-threonate as a novel food pursuant to regulation (EU) 2015/2283 and bioavailability of magnesium from this source in the context of Directive 2002/46/EC. EFSA Journal 22(3): e8656. PMID 38481468
9. Pajuelo D, Meissner JM, Negra T, Connolly A, Mullor JL (2024). Comparative Clinical Study on Magnesium Absorption and Side Effects After Oral Intake of Microencapsulated Magnesium (MAGSHAPE Microcapsules) Versus Other Magnesium Sources. Nutrients 16(24): 4367. PMID 39770988
10. Schuchardt JP, Hahn A (2017). Intestinal Absorption and Factors Influencing Bioavailability of Magnesium, An Update. Current Nutrition and Food Science 13(4): 260-278. PMID 29123461
11. Lopresti AL, Smith SJ (2026). The effects of magnesium L-threonate (Magtein) on cognitive performance and sleep quality in adults: a randomised, double-blind, placebo-controlled trial. Frontiers in Nutrition 12: 1729164. Correction published 15 October 2026 (wording only). PMID 41601871
12. Garrison SR, Korownyk CS, Kolber MR, Allan GM, Musini VM, Sekhon RK et al. (2020). Magnesium for skeletal muscle cramps. Cochrane Database of Systematic Reviews 9: CD009402. PMID 32956536
13. Food Standards Agency. Register of regulated products: novel food authorisation NOVEL-166, magnesium L-threonate monohydrate. Updated 5 March 2026. Accessed 31 October 2026. data.food.gov.uk/regulated-products
14. Regulation (EU) No 1169/2011 on the provision of food information to consumers, as retained in Great Britain, Annex XIII (reference intakes). Accessed 31 October 2026. legislation.gov.uk
15. NHS. Vitamins and minerals: others (magnesium section). Page last reviewed 3 August 2020. Accessed 31 October 2026. nhs.uk/conditions/vitamins-and-minerals/others
16. Nielsen FH, Johnson LK, Zeng H (2010). Magnesium supplementation improves indicators of low magnesium status and inflammatory stress in adults older than 51 years with poor quality sleep. Magnesium Research 23(4): 158-68. PMID 21199787
17. Puścion-Jakubik A, Bartosiewicz N, Socha K (2021). Is the Magnesium Content in Food Supplements Consistent with the Manufacturers' Declarations? Nutrients 13(10): 3416. PMID 34684417
18. Department of Health and Social Care. Great Britain nutrition and health claims (NHC) register, spreadsheet of 19 May 2026. Accessed 31 October 2026. gov.uk