Magnesium threonate: benefits, evidence and dose
What magnesium threonate is, what the trials show for thinking and sleep, how much to take, its side effects and how it compares with glycinate.
- Written by
- Amy D
- Reviewed by
- Nooroots team
- Last updated
- Reading time
- 7 min read
Overview
Magnesium threonate is magnesium joined to threonate, a breakdown product of vitamin C, sold as Magtein. Its appeal is the brain: in rats it raised brain magnesium and improved memory. In people, two small trials found small gains on thinking tests, and sleep results were mixed. Trials used 1 to 2 g a day.
Key points
- What it is: magnesium joined to threonate, a vitamin C breakdown product, sold as Magtein.
- Evidence: memory gains shown in rats; in people, small gains on thinking tests and mixed sleep results.
- Dose: trials used 1 to 2 g a day, giving about 75 to 145 mg of magnesium.
- UK status: allowed in supplements since March 2026, up to 250 mg of magnesium a day.
- Side effects: few in trials, mainly loose stools and headaches.
What is magnesium threonate?
Magnesium threonate is magnesium joined to L-threonate, a natural breakdown product of vitamin C [1]. It's sold as Magtein, and labels may call it magnesium L-threonate.
It carries less magnesium than most forms. Only 7 to 8% of its weight is magnesium, so 1 g gives you roughly 75 mg [1][2]. That's why the magnesium figure on the label matters more than the weight of the compound.
What are the benefits of magnesium threonate?
Its draw is the brain, but most of that evidence comes from rats. In a 2010 study, raising brain magnesium with threonate improved learning and memory in rats [3]. No study in people has yet measured brain magnesium after taking it.
In people, there are three small trials of threonate on its own. Two found small gains on thinking tests, and sleep results were mixed [4][5][6]. All three were funded by companies behind the ingredient.
| Study | People | Dose and length | Result | Evidence |
|---|---|---|---|---|
| Liu 2016 [4] | 51 adults aged 50 to 70 with memory complaints and poor sleep | 1.5 to 2 g a day for 12 weeks | A combined thinking score improved more than on placebo; sleep scores didn't | Early |
| Hausenblas 2024 [5] | 80 adults aged 35 to 55 with poor sleep | 1 g a day for 3 weeks | The main sleep questionnaire was no better than placebo; some tracker and mood scores were | Mixed |
| Lopresti 2026 [6] | 100 adults aged 18 to 45 unhappy with their sleep | 2 g a day for 6 weeks | A small gain on an overall thinking score; sleep measured by a ring didn't change | Early |
Does magnesium threonate help sleep?
Possibly, but the trials don't agree yet. In the 3-week sleep trial, scores on the main sleep questionnaire improved on both magnesium and placebo, and the gap between them was small enough to be chance [5].
Other measures in that trial did favour magnesium: deep sleep and REM scores from a sleep tracker, and daytime mood, alertness and energy [5]. In the 6-week trial, one sleep questionnaire improved slightly and another didn't [6].
For the wider evidence on magnesium and sleep, see magnesium for sleep: what the research shows.
How much magnesium threonate per day?
Trials used 1 to 2 g a day, which gives about 75 to 145 mg of magnesium [5][6]. In the UK, a supplement may give at most 250 mg of magnesium a day from threonate, which takes about 3 g [2].
Trials gave it about 2 hours before bed, or split between morning and evening [5][6]. Count it toward your total magnesium for the day; our guide to how much magnesium per day has the UK amounts.
Is magnesium threonate legal in the UK?
Yes, since March 2026. It was authorised in Great Britain as a novel food, meaning a food not widely eaten before 1997, for use in supplements [2].
The rules are strict. A daily dose can give at most 250 mg of magnesium, and the label must say who shouldn't take it. For five years from March 2026, only the Magtein ingredient from its US owner, AIDP, is authorised [2].
Magnesium threonate side effects
Side effects in trials were few, mild and about as common as on placebo. The main ones were loose stools and headaches [4][6].
Placebo-controlled trials have lasted up to 12 weeks, so less is known about taking it for longer.
Threonate vs glycinate, citrate and malate
Threonate gives much less magnesium per gram than the common forms. No trial has compared them head to head, so there's no evidence yet that one works better than another.
| Form | Magnesium in 1 g | Read more |
|---|---|---|
| Threonate | About 75 mg [1] | This guide |
| Glycinate | About 140 mg | Magnesium glycinate |
| Citrate | About 120 to 160 mg | Magnesium citrate |
| Malate | About 115 to 155 mg | Magnesium malate |
The glycinate, citrate and malate figures are our own sums from each compound's chemical formula. They vary with how an ingredient is made, so go by the magnesium figure on the label.
Where Nooroots fits
Nooroots Triple Magnesium doesn't contain threonate. It combines three everyday forms, glycinate, citrate and malate, to give 301 mg of magnesium in three capsules a day.
Triple Magnesium's magnesium contributes to a reduction of tiredness and fatigue and to the normal functioning of the nervous system.
Coming soon. Triple Magnesium isn't on sale yet.
Frequently asked questions
When should you take magnesium threonate?
Trials gave it about 2 hours before bed, or split between morning and evening [5][6]. No study has compared different times of day, so take it when you'll remember.
How long does magnesium threonate take to work?
Trials measured results after 3 to 12 weeks. In two trials, small gains on thinking tests showed up at 6 weeks [4][6].
Is Magtein the same as magnesium L-threonate?
Yes. Magtein is the trade name of the magnesium L-threonate ingredient, and it's the only one currently authorised in the UK [2].
Can you take magnesium threonate with other magnesium?
UK safety assessors advised against it: threonate is meant to replace other magnesium supplements, not add to them [7]. Choose one magnesium supplement and keep your daily total in check.
Is magnesium threonate better than glycinate?
No trial has compared them. Threonate's research centres on thinking tests, while glycinate gives nearly twice the magnesium per gram; see our magnesium glycinate guide.
Can you take magnesium threonate every day?
Yes, at the dose on the label. Trials gave it every day for up to 12 weeks, and UK rules cap it at 250 mg of magnesium a day [2][4].
References
Every study here is listed so you can read it yourself. This guide is for general information and doesn't replace advice from your GP or pharmacist. We review it when new research is published.
- EFSA Panel on Nutrition, Novel Foods and Food Allergens (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
- Food Standards Agency. Register of regulated products: novel food authorisation NOVEL-166, magnesium L-threonate monohydrate. Updated 5 March 2026. data.food.gov.uk/regulated-products
- Slutsky I et al. (2010). Enhancement of learning and memory by elevating brain magnesium. Neuron 65(2): 165–177. doi:10.1016/j.neuron.2009.12.026
- Liu G et al. (2016). Efficacy and safety of MMFS-01, a synapse density enhancer, for treating cognitive impairment in older adults: a randomized, double-blind, placebo-controlled trial. Journal of Alzheimer's Disease 49(4): 971–990. PMID 26519439
- Hausenblas HA et al. (2024). Magnesium-L-threonate improves sleep quality and daytime functioning in adults with self-reported sleep problems: a randomized controlled trial. Sleep Medicine: X 8: 100121, with a 2025 correction. doi:10.1016/j.sleepx.2024.100121
- 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. doi:10.3389/fnut.2025.1729164
- Food Standards Agency and Food Standards Scotland (2024). Safety assessment: magnesium L-threonate as a novel food for use in food supplements (RP956). doi:10.46756/sci.fsa.ply807
