Magnesium L-Threonate for Memory and Brain Fog: What the Human Trials Show, and Who Paid for Them
The “brain magnesium” story started in rats. Four small human trials of 1 to 2 grams a day report better scores on some cognitive tests, mixed sleep results and no objective sleep change in the largest one. All four were company-funded.
By Kymata Health Editorial Published Last checked
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Momentous Magnesium L-Threonate, 90 capsules
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Its name matches magnesium L-threonate, one of the forms compared in our Forms table.
Label: 3 capsules: 2 g Magtein magnesium L-threonate (145 mg elemental magnesium).
Best for regular use: $37.49 on subscription vs $49.99 one-time (checked Oct 15, 2026).
Key takeaways
From 7 sources- The idea comes from a 2010 rat study in which magnesium L-threonate raised brain magnesium and improved learning and memory1.
- In the largest trial, 100 adults took 2 g a day or placebo for 6 weeks: a composite cognition score and reaction time improved more, but a reasoning test and ring-measured sleep did not4.
- In 44 adults aged 50 to 70 with cognitive impairment, 1.5 to 2 g a day for 12 weeks improved an overall cognitive score versus placebo2.
- Magnesium L-threonate is only about 8% magnesium by weight, so a 2 g dose supplies roughly 165 mg of elemental magnesium, under the 350 mg upper limit for supplements67.
- All four trials were company-funded, by Neurocentria, Wu-xi Magtein Bioscience, AIDP and Threotech; Threotech also supplied the product it tested2354.
What this article covers
2 evidence profilesThe evidence, graded
Pulled from the trial tables in our evidence profiles. Grades follow our evidence-grading policy.
Graded findings
2 rows- CGrade COverall cognitive performanceImproved Greater improvement than placebo on the NIH Toolbox total cognition composite (p = 0.043) and reaction time; no difference on Raven's matrices.Magnesium L-threonate · RCT · n=100 · 2025 · PMID 41601871
- CGrade CSleep qualityMixed Ring-measured deep and REM sleep scores and several self-rated daytime measures improved versus placebo. In a 6-week trial of 2 g/day (n=100), ring-measured sleep did not differ and only some self-rated measures improved, so results are mixed.Magnesium L-threonate · RCT · n=80 · 2024 · PMID 39252819
Safety at a glance
From our Magnesium L-threonate evidence profilePublished interactions and cautions only. Each one is cited on our Magnesium L-threonate evidence profile, with its own numbered sources.
Interactions
- Oral bisphosphonates
- L-threonate supplies magnesium like any salt; NIH ODS advises a 2-hour gap from bisphosphonates.
- Tetracycline and quinolone antibiotics
- Magnesium latches onto these drugs. Take them 2 hours before your threonate dose or 4–6 hours after it.
- Levothyroxine
- In a crossover study of 15 healthy adults, a 1 mg dose of levothyroxine given together with 243–301 mg of magnesium cut thyroxine absorption by 12% with magnesium aspartate and by 7% (not significant) with magnesium citrate. The authors advise spacing levothyroxine apart from magnesium products. Threonate itself was not tested.
- Potassium-sparing diuretics
- Reduce kidney excretion of magnesium.
Who should be careful
- Kidney problems
- Threonate's magnesium is still cleared by the kidneys, so impaired function means a toxicity risk.
- High intakes and digestive effects
- At high doses expect diarrhea, nausea or abdominal cramps. Only the elemental magnesium in threonate counts toward 350 mg/day; laxative or antacid doses over about 5,000 mg/day have caused toxicity.
- Pregnancy and breastfeeding
- No threonate-specific pregnancy data. EFSA's 2024 safety opinion covered adults except pregnant and lactating women. ODS RDAs are 350–400 mg/day pregnant and 310–360 mg/day lactating, with pill magnesium capped at 350 mg.
- Children
- For children, supplement magnesium is capped at 65 mg/day (1–3) and 110 mg/day (4–8).
Where the brain claim comes from
In a 2010 study in Neuron, researchers developed magnesium L-threonate and showed that raising brain magnesium with it improved learning, working memory and short- and long-term memory in rats, with more synaptic markers in the hippocampus1. That rat finding is why the compound is marketed as the magnesium that reaches the brain. Rat results do not always carry over to people, which is why the human trials matter.
The four human trials
Here is what each trial tested and found:
- Older adults with cognitive impairment (2016): 44 people aged 50 to 70 took the compound, branded MMFS-01, at 1.5 or 2 g a day by body weight, or placebo, for 12 weeks; the overall cognitive score improved more than placebo, with a large effect size (Cohen’s d 0.91)2. Strong placebo effects meant the effect on sleep and anxiety could not be determined2.
- Healthy Chinese adults (2022): 109 people aged 18 to 65 took 2 g a day of a formula combining magnesium L-threonate with phosphatidylserine and vitamins C and D, or starch placebo, for 30 days, and memory test scores improved3. Because the capsule had several active ingredients, it cannot isolate the magnesium3.
- Adults with sleep problems (2024): 80 people aged 35 to 55 took 1 g a day or placebo for 21 days; ring-measured deep and REM sleep scores and self-rated mood, energy and alertness favoured the supplement5.
- Adults with poor sleep (2025): 100 people aged 18 to 45 took 2 g a day or placebo for 6 weeks; the NIH Toolbox total cognition score improved more on the supplement (p = 0.043), as did reaction time, but Raven’s reasoning test did not differ and ring-measured sleep showed no group differences4.
Who funded the research
Three of the trials named their product, Magtein or MMFS-01234. The 2016 trial was funded by Neurocentria, which also helped design it2. The 2022 Chinese trial was funded by Wu-xi Magtein Bioscience3. The 2024 sleep trial was funded by AIDP, which employed three of its authors5. The 2025 trial was funded by Threotech, which supplied the product and was involved in designing the study4.
Industry funding does not make a result wrong, but it is a reason to want independent replication. Our magnesium L-threonate page grades the cognition and sleep findings C.
Dose and label math
Magnesium L-threonate has a molecular weight of about 294.5, and magnesium makes up only about 8% of it7. So the 2 g a day used in most trials supplies roughly 165 mg of elemental magnesium, and the 1 g dose about 80 mg7. The tolerable upper limit for magnesium from supplements is 350 mg a day for adults, and it counts elemental magnesium only6.
If you stack threonate with another magnesium product, add up the elemental amounts; our magnesium upper limit guide walks through it. High supplement doses can cause diarrhea, nausea and cramps, and people with kidney problems face a higher risk of magnesium building up6.
Should you pick threonate over other forms?
For memory, threonate has a few dedicated human cognitive trials, though they are small and all industry-funded24. For sleep the picture is mixed: one trial found ring-measured gains, the larger one did not54. If your goal is simply to meet your magnesium needs, other forms supply more elemental magnesium per gram; compare them in best magnesium supplement and magnesium glycinate vs citrate. For other focus supplements, see does lion’s mane work.
Quick answers
Common questions
4 answersDoes magnesium L-threonate help sleep?
How much elemental magnesium is in magnesium L-threonate?
About 8% by weight, so roughly 165 mg in a 2 g serving7.
Keep reading
Full evidence profiles
Every graded study, studied doses, interactions and safety- MineralMagnesium L-threonateMagnesium salt of L-threonic acid (about 8% magnesium by weight), studied for cognition and sleep in small RCTs.CGrade C
- MineralMagnesiumEssential mineral involved in over 300 enzyme systems; sold as glycinate, citrate, threonate, malate, taurate, oxide and other salts.AGrade A
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3 capsules: 2 g Magtein magnesium L-threonate (145 mg elemental magnesium); 30 servings
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References
7 sources. Numbers in the text link here.
Sources cited in this article
7 sources- 1Enhancement of learning and memory by elevating brain magnesiumNeuron, 2010 · PMID 20152124
- 2Efficacy and Safety of MMFS-01, a Synapse Density Enhancer, for Treating Cognitive Impairment in Older Adults: A Randomized, Double-Blind, Placebo-Controlled TrialJ Alzheimers Dis, 2016 · PMID 26519439
- 3A Magtein®, Magnesium L-Threonate, -Based Formula Improves Brain Cognitive Functions in Healthy Chinese AdultsNutrients, 2022 · PMID 36558392
- 4The effects of magnesium L-threonate (Magtein®) on cognitive performance and sleep quality in adults: a randomised, double-blind, placebo-controlled trialFront Nutr, 2025 · PMID 41601871
- 5Magnesium-L-threonate improves sleep quality and daytime functioning in adults with self-reported sleep problems: A randomized controlled trialSleep Med X, 2024 · PMID 39252819
- 6Magnesium: Fact Sheet for Health Professionals (updated January 6, 2026)NIH Office of Dietary Supplements, 2026
- 7Magnesium L-threonate (CID 45489777): C8H14MgO10, MW 294.50PubChem, NIH, 2026
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