Magnesium L-threonate is the newest of the common forms, developed in 2010 and usually sold under the branded ingredient name Magtein. Its pitch is brain delivery: in animal studies it raises magnesium levels in the brain more effectively than other forms, which is why every bottle mentions memory and focus.
It’s also several times the price of the alternatives, so the question worth answering is whether the evidence justifies that.
Already decided? Skip to the fair summary, or see what I take.
Where it came from
The form was created by researchers at MIT and described in a 2010 paper in Neuron by Slutsky and colleagues. Feeding rats magnesium L-threonate raised magnesium concentrations in the brain and improved learning, working memory, and both short and long-term memory.
What the human trials found
The human evidence is thinner but no longer absent.
A 2024 randomised controlled trial by Hausenblas and colleagues gave 80 adults aged 35 to 55 with self-reported sleep problems either magnesium L-threonate or placebo. Using an Oura ring for objective measurement, the magnesium group showed better deep sleep and REM scores than placebo, alongside self-reported improvements in daytime energy, alertness and mood on waking.
The detail that makes this trial useful is what it says about placebo. Both groups improved sharply in the first week. The difference was that the placebo group then plateaued while the magnesium group kept improving, and the objective wearable data separated the two more clearly than the questionnaires did.
A 2026 review by Lopresti and Smith covers the wider picture for cognition. The pattern there is familiar: some small randomised trials report improvements on cognitive measures, sample sizes are small, and several trials were funded by the ingredient’s maker.
The fair summary
Promising is a fair description. Proven isn’t, at least not yet.
There’s a real mechanism from animal work, one decent human sleep trial with objective measurements, and a handful of small cognitive studies with funding caveats. That’s more than nothing and less than the marketing suggests.
If the cognitive angle interests you and the price doesn’t hurt, it’s a reasonable bet on early science. If you’re on a budget, spend it on getting your overall magnesium intake right first with a cheaper form.
The elemental magnesium problem
This catches people out. L-threonate carries relatively little elemental magnesium for its bulk, so a serving delivering 144mg typically means three capsules, and it’s a smaller dose than you’d get from a single cheap citrate tablet.
If your goal is raising your overall magnesium levels, threonate is an expensive way to do it. If your goal is specifically the brain angle, that’s the trade you’re making knowingly.
Who it suits
People chasing cognitive or age-related brain goals who have money to spare and understand the evidence is early. Also, on the strength of the 2024 trial, people whose sleep problems come with daytime fog rather than trouble falling asleep, though glycinate remains the cheaper first thing to try for sleep generally.
Dosing basics
Trials have generally used doses around 1,500 to 2,000mg of magnesium L-threonate, which delivers roughly 144mg of elemental magnesium, usually split across three capsules taken in the evening.
Check the elemental figure on any product you’re comparing, because the headline number on the front is the compound weight and it looks far more impressive.
The usual cautions
The same three groups, on every page, because they matter every time. If your kidneys don’t work well, magnesium supplements can be risky, because the kidneys are what clear it: talk to a doctor first. If you take regular medication, magnesium interacts with several drugs, including some antibiotics, and a pharmacist can check yours in about a minute. If you’re pregnant or breastfeeding, ask your midwife or doctor before starting anything.
Disclosure: the links below are affiliate links. If you buy through one I may earn a small commission, at no extra cost to you. It never changes what I recommend.
Cognitive goals
Jigsaw Health
Brain Boost
Uses Magtein, the branded L-threonate the research was done on. I've taken it for over six months, two capsules most evenings. It's the expensive option, so go in knowing the evidence is early.
- Elemental magnesium144 mg per 3-capsule serving
- Third-party testedThird-party label claim verified
- PriceUS$59.97 for 30 servings, about US$2 a day (roughly A$85 a bottle, A$2.85 a day)
Australian dollar figures are approximate, converted at US$1 = A$1.42 (checked August 2026), and exclude international postage.
Is it worth the extra cost? Only if the brain angle is specifically what you want. For general magnesium top-up it’s poor value.
Is Magtein different from generic L-threonate? Magtein is the branded ingredient the research was done on. Products using it can point to that research; others are relying on the form rather than the specific studies.
Does it help sleep? The 2024 trial suggests it may, particularly for sleep quality and next-day functioning. Glycinate is still the cheaper starting point.
Sources: Slutsky et al., Enhancement of learning and memory by elevating brain magnesium, Neuron, 2010 (https://pubmed.ncbi.nlm.nih.gov/20152124/); Hausenblas 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 (https://pmc.ncbi.nlm.nih.gov/articles/PMC11381753/); Lopresti & Smith, Frontiers in Nutrition, 2026 (https://www.frontiersin.org/journals/nutrition/articles/10.3389/fnut.2025.1729164/full)
This article is general information, not medical advice.