Magnesium L-Threonate (Magtein): Benefits, Sleep, Dosage And Research

ByJustin Updated on

Magnesium L-threonate is a form of magnesium, sold mainly under the brand name Magtein, that was developed after rat studies showed it raised brain magnesium and improved learning and memory.[1] In people, the evidence is limited to a handful of small, mostly industry-linked trials suggesting modest benefits for memory and sleep.[2][3][4] It supplies relatively little elemental magnesium per gram, so it is a poor choice if your goal is simply to correct low magnesium intake.

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Key Takeaways

  • The “crosses the blood-brain barrier” reputation comes from rat research published in Neuron in 2010; it has not been directly confirmed in humans.[1]
  • Three small human trials (44 to 109 participants, 3 to 12 weeks) reported benefits for cognition or sleep; each was run, funded or co-authored by the ingredient’s developer or supplier.[2][3][4][7]
  • Studied doses are 1 to 2 grams of the compound per day, which provides well under 200 mg of elemental magnesium.
  • For sleep, magnesium glycinate (bisglycinate) now has an independent placebo-controlled trial of its own, with a small benefit.[6]
  • The NIH upper limit for magnesium from supplements is 350 mg per day for adults; more often causes diarrhea.[5]

What Is Magnesium L-Threonate And How Does It Work?

Magnesium L-threonate (often shortened to MgT or “L-threonate”) pairs magnesium with threonic acid, a breakdown product of vitamin C. It was developed by researchers studying how magnesium affects the brain’s synapses, the connections between nerve cells.

Magnesium plays a role in regulating NMDA receptors, which are involved in learning and memory. The 2010 study by Slutsky and colleagues found that giving rats magnesium L-threonate raised magnesium levels in the brain and enhanced learning and memory in both young and aged rats, along with increases in synapse density in the hippocampus.[1] That paper is the foundation for nearly every marketing claim about the compound.

The important caveat: rats are not people, and no published human study has measured brain magnesium before and after magnesium L-threonate. The “brain-penetrating magnesium” claim remains an extrapolation from animal work.

What Is Magtein?

Magtein is the trademarked magnesium L-threonate ingredient used in most products on the market, including well-known brands such as NOW Magtein. If a label says “Magtein,” it contains magnesium L-threonate; if it says “magnesium L-threonate” without the brand, it may come from another manufacturer.

Magnesium L-Threonate Benefits: What The Research Shows

Memory And Cognition In Older Adults (Evidence: Limited)

The first human trial randomized 44 adults aged 50 to 70 with cognitive impairment to MMFS-01 (the developer’s magnesium L-threonate formulation) or placebo for 12 weeks. Overall cognitive scores improved more with MMFS-01 than placebo (Cohen’s d = 0.91), with the largest gains in executive function.[2] It is a promising signal, but only 23 people took the active treatment, and three of the five authors worked for Neurocentria, the company developing MMFS-01. It needs independent replication.

Memory In Healthy Adults (Evidence: Limited)

A 2022 trial in 109 healthy Chinese adults aged 18 to 65 found that 2 grams per day of Magtein PS, a formula that combined magnesium L-threonate with phosphatidylserine and vitamins C and D, improved scores on a clinical memory test after 30 days compared with placebo, with larger improvements in older participants.[3] Two limitations matter: the study was funded by AIDP, the supplier that markets Magtein, and because the formula also contained phosphatidylserine and vitamins, the result cannot be credited to magnesium L-threonate alone.[7]

Sleep (Evidence: Limited)

A 2024 randomized, double-blind trial gave 80 adults aged 35 to 55 with self-reported sleep problems 1 gram per day of magnesium L-threonate or placebo for 21 days. Compared with placebo, the magnesium group had better deep sleep and REM sleep scores measured by an Oura ring, and better self-rated energy, mood and mental alertness.[4] Keep the limits in mind: the authors describe the magnesium group as maintaining its sleep quality while the placebo group declined, the trial lasted only three weeks, consumer wearables are less precise than lab sleep studies, and co-author Jennifer Gu is vice president of research and development at AIDP, the Magtein supplier.[7]

More broadly, magnesium of any form has only weak evidence for sleep. A 2021 meta-analysis of three small trials in older adults found magnesium shortened the time to fall asleep by about 17 minutes, but rated the evidence low to very low certainty.[8]

Anxiety (Evidence: Preliminary)

Magnesium L-threonate is often listed among the “best magnesium supplements for anxiety,” but there is no dedicated human anxiety trial. In the 2016 trial, strong placebo responses meant the researchers could not determine an effect on anxiety.[2]

Magtein Dosage: Studied Doses

Purpose Dose Duration Study
Cognitive impairment, ages 50–70 MMFS-01 (magnesium L-threonate formulation), daily 12 weeks Liu 2016[2]
Memory, healthy adults 2 g/day Magtein PS (with phosphatidylserine, vitamins C and D) 30 days Zhang 2022[3]
Sleep quality 1 g/day magnesium L-threonate 21 days Hausenblas 2024[4]

Most products recommend about 2,000 mg of magnesium L-threonate per day, often split into a daytime and an evening dose. Pay attention to the difference between the weight of the compound and the elemental magnesium it contains.

Elemental Magnesium Content Is Low

Based on its chemical formula, magnesium makes up only about 8% of magnesium L-threonate by weight (less in hydrated forms). That means 2,000 mg of the compound supplies at most about 165 mg of elemental magnesium, and 1,000 mg supplies roughly 80 mg. By comparison, magnesium bisglycinate is about 14% magnesium: one trial used 893 mg of bisglycinate to deliver 125 mg of magnesium.[6] The adult RDA is 400 to 420 mg for men and 310 to 320 mg for women, most of which should come from food.[5] Always check the “elemental magnesium” line on the Supplement Facts panel.

Magnesium L-Threonate Vs Glycinate

Magnesium glycinate (also called bisglycinate) binds magnesium to the amino acid glycine. It is the form most often recommended as a magnesium supplement for sleep, and it is far more widely searched than L-threonate. Here is how they compare.

Factor Magnesium L-Threonate Magnesium Glycinate
Elemental magnesium About 8% or less by weight About 14% by weight[6]
Main research focus Memory, cognition, sleep Sleep, general magnesium repletion
Key sleep trial 80 adults, 1 g/day, 21 days, wearable data[4] 155 adults, 250 mg elemental Mg/day, 4 weeks, small benefit (d = 0.2)[6]
Who funded the trials Developer or supplier linked[7] University internal project; product made by a supplement company[6]
Cost per mg of magnesium High Low to moderate

In the 2025 bisglycinate trial, 155 adults with poor sleep took 250 mg of elemental magnesium as bisglycinate or placebo 30 to 60 minutes before bed for four weeks. Insomnia Severity Index scores fell more with magnesium (−3.9 vs −2.3 points), a statistically significant but small effect that relied on self-reported sleep only.[6]

Our take: if you want a magnesium supplement for sleep or to fill a dietary gap, glycinate delivers more magnesium per capsule at a lower cost and has comparable (still modest) evidence. Magnesium L-threonate makes more sense if you are specifically interested in its cognitive research and accept that this evidence is early and industry-linked. Some people take both, but keep total supplemental magnesium within the 350 mg daily limit.[5] Forms like magnesium taurate are also marketed for sleep, but we did not find human sleep trials of taurate specifically.

Forms And What To Look For

  • Capsules vs powder. Magtein powder and bulk magnesium L-threonate powder are cheaper per gram, but you need an accurate milligram scale to dose 1 to 2 grams.
  • Branded Magtein. The human trials used Magtein or its precursor formulation; generic L-threonate may be equivalent but is untested.
  • Elemental magnesium listed. A reputable label states both the compound weight and the elemental magnesium.
  • Third-party testing. Look for a certificate of analysis for purity and heavy metals.

Side Effects And Safety

Magnesium L-threonate was described as safe and well tolerated in the 2024 sleep trial.[4] General magnesium safety rules still apply. The NIH sets a Tolerable Upper Intake Level of 350 mg per day for adults for magnesium from supplements and medications (not food). Higher supplemental doses often cause diarrhea, nausea and abdominal cramping, and very high doses can cause dangerously low blood pressure and irregular heartbeat.[5] Some users report drowsiness or headaches when starting; if so, take it in the evening or lower the dose.

Drug Interactions And Who Should Avoid It

According to the NIH Office of Dietary Supplements, magnesium can interact with several medications:[5]

  • Bisphosphonates (such as alendronate): separate by at least 2 hours.
  • Tetracycline and quinolone antibiotics: take the antibiotic at least 2 hours before or 4 to 6 hours after magnesium.
  • Diuretics: loop and thiazide diuretics increase magnesium loss; potassium-sparing diuretics reduce it.
  • Proton pump inhibitors: long-term use can lower magnesium levels.

People with kidney disease should not take magnesium supplements without medical advice, because impaired kidneys cannot clear excess magnesium and toxicity risk rises.[5]

How Magnesium L-Threonate Stacks With Other Nootropics

Because it is mainly taken for sleep and long-term cognition, magnesium L-threonate pairs naturally with evening ingredients. L-theanine and apigenin are common partners in sleep stacks, though no trial has tested these combinations. For daytime cognition, it is sometimes combined with phosphatidylserine, which mirrors the formula in the 2022 memory trial.[3] See our nootropic stacks guide and our roundup of the best supplements for memory.

Where To Buy Magnesium L-Threonate

For a single-ingredient product, look for branded Magtein with the elemental magnesium clearly listed. Nootropics Depot sells standardized, third-party-tested single ingredients; on Amazon, buy only from listings marked “Sold by Nootropics Depot.”

Check Nootropics Depot Magnesium L-Threonate

Does Mind Lab Pro Contain Magnesium?

No. Mind Lab Pro does not contain magnesium L-threonate or any magnesium. It is a broad daytime cognitive stack built around citicoline, bacopa, lion’s mane and phosphatidylserine (100 mg, below the 300 mg used in many PS studies). If you want magnesium for sleep, take it separately in the evening; Mind Lab Pro and a magnesium supplement can be used together.

Check Mind Lab Pro Price

Magnesium L-Threonate FAQs

Is Magnesium L-Threonate Good For Sleep?

One 21-day trial in 80 adults found better wearable-measured deep and REM sleep scores versus placebo at 1 gram per day.[4] That is encouraging but preliminary, and the study was industry-linked.

What Is The Best Magnesium Supplement For Sleep?

No form has strong evidence. Glycinate has the largest recent placebo-controlled sleep trial and more magnesium per dose; L-threonate has a smaller trial with wearable data.[4][6] If your diet is low in magnesium, correcting that is the most sensible starting point.

What Is The Magtein Dosage?

Trials used 1 to 2 grams per day of the compound.[3][4] Most labels suggest 2,000 mg daily, often split between afternoon and evening.

Does Magnesium L-Threonate Cross The Blood-Brain Barrier?

It raised brain magnesium in rats.[1] Whether it does so meaningfully better than other forms in humans has not been directly measured.

Can I Take Magnesium L-Threonate And Glycinate Together?

Yes, many people do. Add up the elemental magnesium from both and keep the supplemental total at or below 350 mg per day unless a doctor advises otherwise.[5]

Is Magnesium L-Threonate A Nootropic?

It is marketed as one, and early trials suggest possible memory benefits, but the human data are small and industry-linked.[2][3] For context on what counts as a nootropic, see what are nootropics.

Medical disclaimer: This article is for educational purposes only and is not medical advice. Dietary supplements are not evaluated by the FDA to diagnose, treat, cure or prevent any disease. Talk with your doctor or pharmacist before starting a supplement, especially if you are pregnant, nursing, take prescription medication or have a medical condition. Read our full medical disclaimer.

References

  1. Slutsky I, et al. Enhancement of learning and memory by elevating brain magnesium. Neuron. 2010;65(2):165-177. PubMed
  2. Liu G, 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):971-990. PubMed
  3. Zhang C, et al. A Magtein, magnesium L-threonate, -based formula improves brain cognitive functions in healthy Chinese adults. Nutrients. 2022;14(24):5235. PubMed
  4. Hausenblas HA, 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
  5. NIH Office of Dietary Supplements. Magnesium: Fact Sheet for Health Professionals. NIH ODS
  6. Schuster J, et al. Magnesium bisglycinate supplementation in healthy adults reporting poor sleep: a randomized, placebo-controlled trial. Nat Sci Sleep. 2025;17:2027-2040. DOI
  7. NutraIngredients. AIDP’s Magtein boosted memory scores in study on healthy adults. December 15, 2022. NutraIngredients
  8. Mah J, et al. Oral magnesium supplementation for insomnia in older adults: a systematic review and meta-analysis. BMC Complement Med Ther. 2021;21(1):125. PubMed

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