Magnesium L-Threonate

What is magnesium L-threonate?

Magnesium L-threonate (sometimes "Magtein") is a magnesium salt bonded to L-threonic acid, a metabolite of vitamin C. It was developed in 2010 by researchers at MIT explicitly to address one limitation of conventional magnesium supplements: poor central nervous system penetration. Most magnesium forms — citrate, oxide, glycinate — efficiently raise serum magnesium but barely move brain magnesium concentrations.

How magnesium L-threonate works

Brain magnesium is a critical co-factor for NMDA-receptor function, synaptic density, and long-term potentiation — the cellular basis of memory and learning. Animal studies show that L-threonate, unlike other forms, raises cerebrospinal-fluid magnesium measurably, with downstream increases in synaptic density in the hippocampus and prefrontal cortex.

The same mechanism plausibly drives its effects on sleep: NMDA tone and GABA balance are tightly linked, and magnesium acts as a natural NMDA-receptor regulator. Adequate brain magnesium is associated with better sleep architecture, particularly deeper slow-wave sleep.

What the evidence shows

Human evidence is younger and smaller than for many other ingredients in this library, but consistent within the studies done.

• A 2016 pilot trial in Journal of Alzheimer's Disease found 12 weeks of magnesium L-threonate improved overall cognitive ability and executive function in older adults with cognitive complaints versus placebo [1].
• A 2022 randomized trial in Sleep Medicine found 12 weeks of magnesium L-threonate at 2 g/day improved sleep quality and daytime function in adults with sleep complaints [2].
• A 2010 animal study in Neuron (the original MIT paper) established that L-threonate raised brain magnesium and reversed age-related synaptic decline in rats [3].

Evidence level: moderate for sleep and cognitive effects in humans; strong mechanistic and preclinical support.

Magnesium L-threonate for menopause and women over 40

Two midlife realities converge here. First, sleep architecture changes meaningfully across the menopause transition — slow-wave and REM sleep both decline, even in women without overt hot flashes — and brain magnesium is one of the few non-prescription levers that affects sleep at a structural rather than sedative level. Second, the "brain fog" that women describe in perimenopause has measurable substrate: declining estradiol affects synaptic density in exactly the regions L-threonate targets.

For these reasons, magnesium L-threonate sits in our menopause sleep supplements protocol and pairs particularly well with ashwagandha KSM-66 for women with the wired-but-tired 3am-waking pattern.

For women who simply need systemic magnesium repletion (constipation, muscle cramps, low serum magnesium), magnesium glycinate or citrate is a better and far cheaper choice. L-threonate is a specifically neurological supplement, not a general magnesium top-up.

Dosage used in research

The dose used in human trials is 2 g/day of magnesium L-threonate (delivering ~144 mg elemental magnesium), typically split into a morning and evening dose, with the evening dose taken 1–2 hours before bed for sleep effects. Discuss dosing with your provider, especially if you have kidney disease.

Safety and interactions

Magnesium L-threonate is generally well tolerated. Because elemental magnesium per gram is low compared with magnesium oxide, the GI side effects (loose stools) typical of magnesium are usually absent. People with severe kidney disease should not take any supplemental magnesium without supervision. Drug interactions include some antibiotics (tetracyclines, quinolones) and bisphosphonates, which should be separated by 2 hours.

Where you will find it at kindr

Magnesium L-threonate is in our Deep Sleep Formula and is the foundational ingredient in our menopause cognition stack.

Medically reviewed by Dr. Ana Lisa Carr, MD, MBA
Board-Certified Family Medicine Physician · Lead Provider / Medical Reviewer
NPI 1689841744 · Last reviewed: May 10, 2026