Supplement

Magnesium L-threonate

Q: Does magnesium L-threonate really get into the brain better?

This was only measured in rats. There, the magnesium concentration in the cerebrospinal fluid after 24 days was around 7 percent above baseline and around 16 percent above the control group. None of the three human studies measured brain or cerebrospinal fluid magnesium. The claim is therefore a transfer from the animal model, not a measurement in humans.

Q: How much magnesium does it actually contain?

Little in relation to the amount of powder. The EU specification states 7.2 to 8.3 percent magnesium; the rest is essentially L-threonate. In the Australian study, 2 grams of the raw material supplied 145 milligrams of elemental magnesium. Anyone who wants to cover their magnesium requirement therefore pays considerably more per milligram with this form than with ordinary salts.

Q: Is magnesium L-threonate permitted in Germany at all?

Yes, since November 7, 2024. The EU has authorized the substance as a novel food for food supplements for adults, with a maximum content of 250 milligrams per day and the exclusion of pregnant and breastfeeding women. Since November 5, 2025, it has also been listed in Annex II of the Food Supplements Directive. Until November 2029, only the authorization holder AIDP Inc. may place it on the market in the EU.

Q: Does it help with sleep?

The data are inconsistent. One study over 21 days reports differences in deep sleep and REM readings from a sleep ring; a second over 6 weeks finds no group difference in the same objective measures and only an improvement in self-reported impairment. In the oldest study, sleep was no better than under placebo. In any case, there is no authorized health claim on sleep for magnesium.

Q: What about the 7.5 years of cognitive age?

This figure comes from the Australian study with 100 participants over 6 weeks. In the methods section it is explicitly labeled as an exploratory analysis, that is, not as a pre-specified endpoint. The actual primary endpoint was an overall cognitive score, which narrowly favored the active group with p equal to 0.043. The figure in years is a conversion of this score to a normative sample.

Q: Is the extra cost worth it compared with citrate or glycinate?

The data cannot answer this, because the comparison was never made. There is no randomized study in humans that has tested magnesium L-threonate directly against another form of magnesium on memory or sleep. The only direct comparison comes from a rat study on absorption in the gut. Anyone who decides therefore decides without comparative data.

Mineral · Magtein, Mg threonate

Magnesium L-threonate is the form of magnesium sold as “brain magnesium”. Its reputation goes back to a 2010 rat study in which the magnesium concentration in the cerebrospinal fluid rose under this compound. In humans, three randomized studies are now available, and since November 2024 the substance has been authorized in the EU as a novel food.

In short

Magnesium L-threonate is a salt of magnesium and L-threonic acid, a breakdown product of vitamin C. It supplies little magnesium per gram – the EU specification states 7.2 % to 8.3 % – and is taken not for the amount, but because of the claim that it gets magnesium into the brain better. This claim has never been measured in humans: the cerebrospinal fluid values come from rats. Three randomized studies with 51, 80 and 100 participants report better test performance and in part better sleep, but all three were paid for by manufacturers. Independent confirmation is lacking, as is any comparison against an ordinary form of magnesium.

What makes this compound special

In supplements, magnesium is always present as a salt, bound to a partner: oxide, citrate, glycinate, malate. Here this partner is L-threonic acid, a sugar acid formed during the breakdown of vitamin C. The EU specification describes a white powder of 7.2 % to 8.3 % magnesium and 82 % to 91 % L-threonate.

This leads to the first practical peculiarity: the magnesium content is small. In the Australian study, 2 g of the raw material supplied 145 mg of elemental magnesium. By far the larger part of the powder is the threonate – and that part is precisely the reason the compound exists at all.

Where the brain narrative comes from

The original observation was published in Neuron in 2010. Rats received magnesium L-threonate in their drinking water, target dose 50 mg of elemental magnesium per kilogram of body weight per day. On day 24, the magnesium concentration in the cerebrospinal fluid was around 7 % above baseline and around 16 % above the control group. In addition, there was a higher density of synaptic markers in the hippocampus and better memory performance in the animals.

The finding is real, and it addresses a real hurdle: magnesium in the blood gets into the brain only poorly. Liu and colleagues themselves write in their later human study that in humans, raising blood magnesium by up to 300 % changes the concentration in the cerebrospinal fluid by less than 19 %. But no human study measured brain or cerebrospinal fluid magnesium. What is sold as a unique selling point is an animal finding that is assumed in humans rather than tested.

What has been tested in humans

Three randomized, placebo-controlled studies are available: 51 older adults with memory complaints over 12 weeks, 80 adults with sleep problems over 21 days, 100 adults over 6 weeks. All three report effects – and all three were paid for by companies that manufacture or distribute the raw material.

Alongside them are two papers worth knowing but not overrating. Surman and colleagues gave the compound to 15 adults with ADHD for up to 12 weeks, open-label and without a control group; 47 % met the responder definition. Zhang and colleagues tested a combination with phosphatidylserine, vitamin C and D in 109 adults over 30 days – there it is impossible to separate which component had an effect.

What is well supported

What is robust, first of all, is the basis: magnesium is available from this compound. EFSA reviewed this in 2024, considers the compound safe under the proposed conditions and sees no indication of genotoxicity. Very few niche supplements have a regulatory assessment with a specification and an upper limit.

On the efficacy side, the most robust single finding is the primary endpoint of the Australian study: pre-specified, prospectively registered, in favor of the active group (p = 0.043), with the larger effects on working and episodic memory. The blinding also held – 54 % of the placebo group and 62 % of the active group guessed wrong or did not know. This fits with the older study by Liu and colleagues, whose cognitive composite score clearly separated from placebo (p = 0.003, Cohen’s d = 0.91).

What the studies show

Liu et al., Journal of Alzheimer’s Disease 2016 – 51 older adults over 12 weeks

Randomized, double-blind, placebo-controlled study in Miami in 51 adults aged 50 to 70 with memory complaints, 25 in the active and 26 in the placebo group, dose about 25 mg per kilogram of body weight per day. 7 participants (14 %) dropped out. The cognitive composite score improved significantly compared with placebo (p = 0.003, Cohen’s d = 0.91); no difference was seen for sleep and anxiety. Funded by Neurocentria Inc. In the registry entry NCT02363634, the primary endpoint listed is magnesium status, not cognition, and the registration was only received on February 4, 2015 – after data collection ended in November 2013.

Hausenblas et al., Sleep Medicine: X 2024 – 80 adults over 21 days

Randomized, double-blind, placebo-controlled study in 80 people aged 35 to 55 with sleep problems, 1 g daily before bedtime for 21 days. Primary endpoints were three sleep questionnaires and the readings of an Oura ring. In the active group, sleep quality and daytime functioning remained stable while they declined under placebo; deep sleep score, REM score and several activity values favored the active group (each p < 0.05). Funded by AIDP Inc.; three of the authors work there. A 2025 corrigendum states that the study was only registered on April 15, 2024, while data collection ended in September 2022, and that the declaration of interests in the original article was incomplete.

Lopresti and Smith, Frontiers in Nutrition 2025 – 100 adults over 6 weeks

Randomized, double-blind, placebo-controlled study in 100 adults aged 18 to 45 with unsatisfactory sleep, 2 g daily for 6 weeks. The pre-specified primary endpoint, an overall cognitive score, favored the active group (p = 0.043), as did reaction time (p = 0.031); Raven’s matrices test showed no difference (p = 0.953). The conversion into a cognitive age, labeled as exploratory, came to 7.5 years. For sleep, only self-reported impairment improved (p = 0.043), not sleep disturbances (p = 0.316) or restorative sleep (p = 0.439); in the objective ring readings there were no group differences. Funded by Threotech Inc., which also supplied the study product.

Where the data stop

The most important caveat concerns the core of the promise. That this form of magnesium reaches the brain better than others has not been measured in humans – the cerebrospinal fluid values are rat values. And to this day there is no randomized study in humans that has tested magnesium L-threonate directly against citrate, glycinate or another ordinary form on a cognitive or sleep endpoint. The only direct comparison in the EFSA opinion is an absorption comparison in rats, in which around 60 % versus around 40 to 45 % was absorbed.

Then there is who paid for the data: Neurocentria, AIDP, Threotech. An independently funded replication does not exist. Two of the three papers were only registered after data collection, and one of them had to submit its declaration of interests later. The endpoints are questionnaires, test batteries and ring readings; there are no hard endpoints, and the longest study ran for 12 weeks. The much-cited figure of 7.5 years of cognitive age is labeled as an exploratory analysis. And the two sleep studies contradict each other where it counts: Hausenblas and colleagues report differences in the objective ring readings, Lopresti and Smith find none in the same measures.

Status, approval and legal

The legal status has changed considerably recently. With Implementing Regulation (EU) 2024/2694, magnesium L-threonate was added to the Union list of novel foods as of November 7, 2024 – for food supplements for adults, excluding pregnant and breastfeeding women, with a maximum content of 250 mg per day and a mandatory labeling statement. The authorization is based on protected data: until November 7, 2029, the compound may only be placed on the market in the EU by AIDP Inc. With Regulation (EU) 2025/2225 it was additionally added to Annex II of Directive 2002/46/EC and is thus formally considered a source of magnesium. The scope for advertising remains narrow: only the general magnesium claims of Regulation (EU) No 432/2012 are authorized, for example on the reduction of tiredness. There is no claim on sleep, memory or concentration. Minerals are not on the doping prohibited list; NADA does, however, point out the contamination risk of food supplements.

Safety

EFSA assessed a maximum intake of 3,000 mg of the compound per day, corresponding to around 2,730 mg of L-threonate and 250 mg of magnesium, and considers this safe; the up to 1 % oxalic acid amounts to up to 30 mg per day, which the authority does not consider problematic. For supplemental magnesium an upper limit of 250 mg per day applies, derived from mild diarrhea at intakes of around 360 to 365 mg; the BfR proposes the same 250 mg, and the US reference values state 350 mg. The typical side effect is diarrhea with nausea and abdominal cramps; in the Australian study, the rate of intake-related side effects was 8.0 % under placebo and 10 % under the active product. According to the authorization, the compound is not suitable for pregnant and breastfeeding women. With impaired kidney function, the risk of overload increases – here any magnesium intake should be clarified with a doctor. Magnesium also reduces the absorption of bisphosphonates and forms poorly soluble complexes with tetracyclines and quinolones, which is why a time gap is recommended.

BK-Score Thin human evidence

Human evidence		5
Mechanism		3
Safety data		6
Hype gap		3
Track record of use		6

The entire unique selling point rests on an unconfirmed step: that this form of magnesium brings magnesium into the brain comes from the cerebrospinal fluid of rats – there around 7 % above baseline and around 16 % above control on day 24 – and has not been measured in living humans in any of the available studies. Three randomized studies with 51, 80 and 100 participants over 3 to 12 weeks report better cognitive composite scores and in part better sleep; all three were funded by manufacturers or raw material suppliers, and two were only registered after data collection had ended. The much-cited 7.5 years of cognitive age are explicitly labeled as an exploratory analysis in the original paper, and the two sleep studies contradict each other in the objective readings of the same sleep ring. The evidence axis rises from 4 to 5 because there are three RCTs and not two; use rises from 5 to 6 because the substance has been authorized in the EU as a novel food since November 7, 2024 and has been listed in Annex II of Directive 2002/46/EC since November 5, 2025.

The score rates the state of knowledge, not the substance. “Safety data 9” means well studied – not harmless.
Subjective assessment by Biohacking Kompakt based on published scoring rules – not a scientific rating and not a medical recommendation. Rules and all ratings (German)

Frequently asked questions about magnesium L-threonate

Does magnesium L-threonate really get into the brain better?