The short answer
Magnesium L-threonate raised brain magnesium and improved memory in rats. In people, two placebo-controlled trials reported better memory scores and better sleep, but both were linked to the company that sells the branded ingredient and neither has been repeated independently. It contains only about 8% magnesium and is the most expensive form.
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What is magnesium L-threonate?
Magnesium bound to L-threonic acid, a breakdown product of vitamin C. It was developed by researchers at the Massachusetts Institute of Technology and is sold under the brand name Magtein. At about 8% magnesium by weight, it holds less magnesium per gram than any other common form.
Where did the brain claims come from?
A 2010 study in the journal Neuron. Rats given magnesium L-threonate had higher magnesium in their cerebrospinal fluid than rats given other forms, more connections between nerve cells in the hippocampus, and better results on learning and memory tasks. It was a careful study, but it was in rats.
What do the human trials show?
Memory, 2022. In a double-blind trial in China, 109 healthy adults aged 18 to 65 took 2 g a day of a formula based on magnesium L-threonate, or a starch placebo, for 30 days. The formula also contained phosphatidylserine and vitamins C and D. The supplement group did better on a standard Chinese memory test. Because of the extra ingredients, the effect of magnesium L-threonate alone cannot be separated out. One author works for a consultancy in the supplement industry.
Sleep, 2024. In a US trial (covered with the other sleep trials in magnesium for sleep), 80 adults aged 35 to 55 with sleep problems took 1 g a day of magnesium L-threonate or placebo for 21 days. The magnesium group scored better on several questionnaires about sleep and daytime energy, and on ring-tracker measures of deep and REM sleep. Three of the authors work for the company that distributes the ingredient.
Does it help memory or brain fog in older adults?
Not proven. A small 2016 pilot study in older adults with memory complaints, run by the company behind the ingredient, reported better test scores, but it had no independent replication. No trial has tested magnesium L-threonate in people with diagnosed dementia. Magnesium for the brain remains an interesting research idea rather than an established treatment; see the benefits overview for how it compares with better-tested uses.
Is magnesium L-threonate worth it?
Probably not as your first choice. The human evidence is small, short and industry-linked, and other forms have similar sleep data at a fraction of the cost. If you want to try it, use our cost calculator to compare the real price per 100 mg of magnesium against glycinate or citrate.
Is magnesium L-threonate safe?
The trials reported no serious side effects, and at about 8% magnesium the doses used provide only around 80 to 150 mg of magnesium a day, so gut upsets are less likely than with oxide or citrate (see side effects). The usual magnesium cautions apply: avoid it if you have kidney disease unless your doctor advises it, and check medicines it affects.
Keep reading
- Epsom salt baths and magnesium sprays: can skin absorb magnesium?
Do Epsom salt baths, magnesium flakes, oils and sprays raise your magnesium? What the research says about absorption through the skin.
- Magnesium glycinate: benefits, dose and how it compares
What magnesium glycinate (bisglycinate) is, how much magnesium a capsule really holds, the trial evidence for sleep, and how it compares with citrate.
- Magnesium citrate: uses, dose and side effects
Magnesium citrate explained: how much magnesium it contains, why it is one of the best-absorbed forms, its laxative effect, and how to take it.
Common questions
Is Magtein the same as magnesium L-threonate?
Magtein is the trademarked brand of magnesium L-threonate, and most products and trials use it.
How much magnesium is in magnesium L-threonate?
About 7 to 8% by weight. A typical 2 g daily dose of magnesium L-threonate provides only about 145 to 165 mg of magnesium, so it is an expensive way to meet your needs.
Does magnesium L-threonate improve memory?
It is not proven. The only human trial we found used a formula that also contained phosphatidylserine and vitamins, was tested in healthy Chinese adults for 30 days, and involved a researcher from a consultancy linked to the product. Independent trials are needed.
Is magnesium L-threonate better than glycinate for sleep?
Nobody has compared them directly. Both have one small placebo-controlled sleep trial, and glycinate is much cheaper per milligram of magnesium.
References
- Slutsky I et al. Enhancement of learning and memory by elevating brain magnesium. Neuron, 2010.pubmed.ncbi.nlm.nih.gov
- Zhang C et al. A Magtein, magnesium L-threonate-based formula improves brain cognitive functions in healthy Chinese adults. Nutrients, 2022.pubmed.ncbi.nlm.nih.gov
- 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 Medicine: X, 2024.pubmed.ncbi.nlm.nih.gov Three authors work for the company that distributes the branded ingredient.
- 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. Journal of Alzheimer's Disease, 2016.pubmed.ncbi.nlm.nih.gov
First published 4 November 2026. Spotted an error? Tell us and we'll correct it. Read our editorial policy.