Home Ingredients Magnesium L-Threonate (Magtein)
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Magnesium L-Threonate (Magtein)

Evidence Level
Moderate
2 Clinical Trials
4 Documented Benefits
3/5 Evidence Score

Magnesium L-threonate is the magnesium salt of L-threonic acid, sold most often under the branded name Magtein. In rats it raises magnesium in the brain and cerebrospinal fluid more than other magnesium forms, and this preclinical finding is the reason it is chosen when the goal is cognition, memory, or a racing mind rather than general magnesium repletion. That brain-magnesium effect has been shown in animals only and has not been measured in people. Human trials report improvements in cognitive performance, sleep quality, and daytime functioning, though the studied doses are high (1,000 to 2,000 mg of the compound) and deliver only about 144 mg of elemental magnesium. It is gentle on the gut but the most expensive magnesium form.

Studied Dose 1,000 to 2,000 mg of magnesium L-threonate per day (about 144 mg elemental magnesium), commonly split into two or three doses with a portion in the evening.
Active Compound Magnesium L-threonate, the magnesium salt of L-threonic acid (branded as Magtein); about 7.2% elemental magnesium by weight.

Benefits

Cognition and Memory

Magnesium L-threonate is the magnesium form best studied for the brain. In a randomized trial in older adults with cognitive complaints (MMFS-01), it improved overall cognitive scores versus placebo, with the largest gains in those who started with greater executive-function deficits.

Supported by Trial 1

Sleep Quality

Randomized controlled trials in adults with self-reported sleep problems found that magnesium L-threonate improved sleep quality and next-day functioning, with reports of more restful sleep and better mood on waking.

Supported by Trial 2

Brain Magnesium Delivery

Unlike most forms, L-threonate raises magnesium concentrations in the brain and cerebrospinal fluid in preclinical work, which is the basis for using it when the target is mental rather than muscular or digestive.

Supported by Trial 1, Trial 2

Calm and a Quieter Mind

By supporting healthy magnesium status and the balance between excitatory NMDA and calming GABA signaling, it may help with stress and a busy mind at bedtime. This is a mechanism, not a measured result: the trial whose participants had anxiety could not separate its effect on anxiety from a large placebo response, and a later trial found no difference in general wellbeing. It is not a treatment for an anxiety disorder.

Supported by Trial 1

Mechanism of action

1

Crosses the Blood-Brain Barrier

In rodent studies the threonate carrier raised magnesium in the brain and cerebrospinal fluid more than other forms. This has been shown in animals only and has not been measured in the human brain or spinal fluid.

2

Synaptic Density and Plasticity

Elevating brain magnesium increased synapse density and enhanced learning and memory in preclinical models, by supporting NMDA-receptor function and synaptic plasticity.

3

NMDA and GABA Modulation

Like all magnesium, it dampens excitatory NMDA-receptor signaling and supports inhibitory GABA tone, shifting the nervous system toward calm and easier sleep onset.

Clinical trials

1
MMFS-01 in Older Adults with Cognitive Impairment
PubMed

Randomized, double-blind, placebo-controlled trial. Liu G et al., J Alzheimers Dis 2016;49(4):971-90.

Older adults aged 50 to 70 with cognitive complaints and anxiety.

Magnesium L-threonate (MMFS-01) significantly improved overall cognitive ability versus placebo, with the largest effect in participants who had greater baseline executive-function deficits.

2
Sleep Quality and Daytime Functioning RCT
PubMed

Randomized controlled trial. Hausenblas HA et al., Sleep Med X 2024;8:100121.

Adults with self-reported sleep problems.

Magnesium L-threonate improved self-reported sleep quality and daytime functioning versus placebo over the study period.

Side effects and drug interactions

Common Potential side effects

Generally well tolerated and gentle on the stomach, with little of the laxative effect seen with citrate or oxide.
High capsule load: the studied dose is 1,000 to 2,000 mg of the compound, usually two to three capsules per day.
Occasional headache, drowsiness, or restlessness; taking part of the dose earlier in the day can help.
Excess magnesium from any form can cause diarrhea, though this is less common with threonate.

Important Drug interactions

Bisphosphonates (alendronate, risedronate): magnesium reduces their absorption; separate doses by at least 2 hours.
Tetracycline and fluoroquinolone antibiotics: magnesium binds them and lowers absorption; space several hours apart.
Reduced kidney function: magnesium can accumulate; use only under medical supervision.

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Frequently asked questions about Magnesium L-Threonate (Magtein)

What is magnesium L-threonate good for?

It is the magnesium form best studied for the brain. It crosses into the central nervous system and is used for memory, focus, and a racing mind, with trials also reporting better sleep quality. For general sleep and anxiety on a budget, magnesium glycinate is the more common first choice.

How much magnesium L-threonate should I take?

Studies use about 1,000 to 2,000 mg of the compound per day, which provides roughly 144 mg of elemental magnesium. It is usually split into two or three doses, with part taken in the evening. Keep your total magnesium intake sensible and check with your doctor if you have kidney problems.

What is Magnesium L-Threonate?

Magnesium L-threonate is the magnesium salt of L-threonic acid, sold most often under the branded name Magtein. In rats it raises magnesium in the brain and cerebrospinal fluid more than other magnesium forms, and this preclinical finding is the reason it is chosen when the goal is cognition, memory, or a racing mind r…

What is Magnesium L-Threonate used for?

Magnesium L-Threonate is researched primarily for Sleep Health and Cognitive. Magnesium L-threonate is the magnesium form best studied for the brain. In a randomized trial in older adults with cognitive complaints (MMFS-01), it improved overall cognitive scores versus placebo, with the largest gains in those who star…

What is the recommended dosage of Magnesium L-Threonate?

The clinically studied dose is 1,000 to 2,000 mg of magnesium L-threonate per day (about 144 mg elemental magnesium), commonly split into two or three doses with a portion in the evening. Always follow the product label and check with a healthcare provider for personal advice.

Is Magnesium L-Threonate safe, and does it have side effects?

For most healthy adults, Magnesium L-Threonate is well tolerated at studied doses. Reported effects can include: Generally well tolerated and gentle on the stomach, with little of the laxative effect seen with citrate or oxide. High capsule load: the studied dose is 1,000 to 2,000 mg of the compound, usually two to three capsules per day. It may also interact with some medications. Magnesium L-Threonate is not right for everyone, so check with a healthcare provider first if you are pregnant or breastfeeding, have a medical condition, or take prescription medication.

Does Magnesium L-Threonate interact with any medications?

Possible interactions include: Bisphosphonates (alendronate, risedronate): magnesium reduces their absorption; separate doses by at least 2 hours. Tetracycline and fluoroquinolone antibiotics: magnesium binds them and lowers absorption; space several hours apart. If you take prescription medication, check with a pharmacist or doctor before using it.

How strong is the scientific evidence for Magnesium L-Threonate?

NutraSmarts rates the evidence for Magnesium L-Threonate as Moderate (3 out of 5). It is backed by 2 clinical trials and 4 cited references summarized on this page. A higher rating reflects more, larger, and better-designed human studies.

References(4 citations)

Evidence ratings on NutraSmarts are based on the totality of human clinical research, with emphasis on randomized controlled trials, meta-analyses, and systematic reviews. The references below directly support claims made throughout this page.

  1. Slutsky I, Abumaria N, Wu LJ, et al. Enhancement of learning and memory by elevating brain magnesium. Neuron. 2010;65(2):165-77. doi: 10.1016/j.neuron.2009.12.026.PubMedUsed to support: Foundational preclinical work showing magnesium L-threonate raises brain magnesium and enhances learning, memory, and synapse density.
  2. Liu G, Weinger JG, Lu ZL, et al. Efficacy and Safety of MMFS-01, a Synapse Density Enhancer, for Treating Cognitive Impairment in Older Adults: A Randomized, Double-Blind, Placebo-Controlled Trial. J Alzheimers Dis. 2016;49(4):971-90. doi: 10.3233/JAD-150538.PubMedUsed to support: Randomized trial in older adults showing magnesium L-threonate (MMFS-01) improved overall cognition versus placebo.
  3. Hausenblas HA, Lynch T, Hooper S, et al. Magnesium-L-threonate improves sleep quality and daytime functioning in adults with self-reported sleep problems: A randomized controlled trial. Sleep Med X. 2024;8:100121. doi: 10.1016/j.sleepx.2024.100121.PubMedUsed to support: Randomized controlled trial showing improved sleep quality and daytime functioning with magnesium L-threonate.
  4. Lopresti AL, Smith SJ. The effects of magnesium L-threonate (Magtein) on cognitive performance and sleep quality in adults: a randomised, double-blind, placebo-controlled trial. Front Nutr. 2025;12:1729164. doi: 10.3389/fnut.2025.1729164.PubMedUsed to support: Randomized, double-blind trial in 100 adults aged 18 to 45 with unsatisfying sleep: over 6 weeks Magtein improved overall cognition and reaction time versus placebo, but objective sleep measures and general wellbeing did not differ from placebo. Funded by the ingredient's supplier.