New human study on magnesium L-threonate (Magtein®): what do the results really say?

Magnesium supplements are more popular than ever, but not every form of magnesium gets the same level of scientific attention. One of the most discussed forms in recent years is magnesium L-threonate, also known under the brand name Magtein®. This form is best known for its potential support of cognitive function, focus, and sleep quality. In addition, this form of magnesium is known for its ability to cross the blood-brain barrier, which may make magnesium available more efficiently in the brain.

In 2025, a new placebo-controlled human study was published in the journal Frontiers in Nutrition, in which researchers examined the effects of magnesium L-threonate in healthy adults with reduced sleep quality. But how strong is this study really, and what can we conclude from it?

Study design

The study was conducted as a:

• randomized study
• double-blind study
• placebo-controlled study

In total, 100 adults took part, aged between 18 and 45. All participants reported reduced sleep quality, but were otherwise healthy.

For 6 weeks, the participants received daily:

• 2 grams of magnesium L-threonate
  or
• a placebo

During the study, various cognitive tests were performed. In addition, researchers also used wearables to measure physiological data such as heart rate and HRV (heart rate variability).

What did the researchers find?

According to the results, the magnesium L-threonate group showed improvements in:

• working memory
• reaction time
• hand-eye coordination
• cognitive performance
• subjective sleep quality
• heart rate variability (HRV)

In addition, the researchers reported an improvement in so-called “cognitive age,” with participants scoring on average as if their cognitive performance corresponded to a younger age.

This drew a lot of attention online, because some media translated this as “younger brains.” Still, nuance is important here.

What does “7.5 years younger brains” actually mean?

One of the most striking claims from the study was an improvement in cognitive age by about 7.5 years.

However, that does not mean the brain literally became biologically younger. It concerns a calculated score based on cognitive test results. When someone scores better on memory, reaction time, and attention, this can be translated by the model into a “younger cognitive age”.

So it is mainly a statistical interpretation of test performance, not a direct measurement of biological rejuvenation of the brain.

Why is this study interesting?

This study is designed more robustly than many other supplement studies. This is partly because researchers used:

• placebo control
• double-blind randomization
• objective cognitive tests
• physiological measurements via wearables

The NIH Toolbox was also used, a well-known cognitive testing platform that is more often used in scientific research.

In addition, the results partly align with earlier studies on magnesium L-threonate, which also showed improvements in sleep quality and cognitive performance.

What can we conclude from this?

This human study provides interesting indications that magnesium L-threonate may provide support for:

• cognitive performance
• focus
• working memory
• mental performance under stress
• sleep quality

The combination of cognitive tests and HRV measurements makes this study strong.

Final conclusion

Magnesium L-threonate is currently among the most researched forms of magnesium in the area of cognitive support. This new 2025 study adds to the growing body of evidence that this form may offer benefits for focus, memory, and sleep-related cognitive performance.

References

• Frontiers in Nutrition (2025). Effects of magnesium L-threonate supplementation on cognition, sleep quality and physiological stress markers in healthy adults. Available via: https://www.frontiersin.org/journals/nutrition/articles/10.3389/fnut.2025.1729164/full
• Hausenblas, H. A. et al. (2024). Magnesium L-threonate supplementation and sleep/cognitive outcomes. Nutrients.
• Slutsky, I. et al. (2010). Enhancement of learning and memory by elevating brain magnesium. Neuron, 65(2), 165–177.
• Vink, R. & Nechifor, M. (2011). Magnesium in the Central Nervous System. University of Adelaide Press.