Evidence-based·Last reviewed May 31, 2026·How we grade evidence

Magnesium threonate

MineralMagnesiumBest before bed

A patented magnesium form (Magtein) developed specifically for brain penetrance. The animal data showing it raises CSF magnesium are real and impressive; the human cognitive evidence is positive but modest, comes from small studies, and several were funded by the patent-holder. For non-brain magnesium needs, cheaper forms work as well or better.

Quick decision guide

May help most

Adults with subjective cognitive concerns, mild memory complaints, or sleep difficulty who want to try the form with the most brain-targeted evidence (modest as it is). Don't use for routine magnesium repletion.

Common dosing range

1.5–2 g of magnesium L-threonate per day (≈144 mg elemental magnesium) — usually split 2x/day.

When to expect effects

Days for sleep effects; 6–12 weeks for cognitive endpoints.

Watch out for

Cost premium is substantial vs other magnesium forms. The 350 mg/day supplemental magnesium UL applies — elemental magnesium content from MgT counts.

Evidence snapshot

CSF magnesium increase (animal models)Strong (animal)

Cognitive function in older adults (subjective decline)Emerging

Sleep quality (subjective)Emerging

General magnesium repletionModerate (any form works)

Alzheimer's disease prevention or slowingLow

ADHD, anxiety, migraine (form-specific)Low

What is it

Magnesium L-threonate (sold as Magtein) is a chelated form of magnesium bound to threonic acid, a metabolite of vitamin C. It was developed at MIT specifically to enhance magnesium delivery to the brain and is most commonly marketed for cognitive function, sleep, and memory.

Is it worth it for you?

Use this as a quick fit check, not a diagnosis.

Worth considering if…

You have mild subjective memory complaints or 'cognitive haze' and want to try the form with brain-specific evidence

You've used cheaper magnesium forms (glycinate, citrate) for sleep and want to A/B test threonate for cognitive feel

You're an older adult experimenting with stack interventions for healthy cognitive aging and can absorb the cost

You've tolerated other magnesium forms well and want to escalate to the brain-targeted form

Your goal is specifically cognitive — not laxation, leg cramps, or general repletion

Probably skip if…

Your goal is correcting magnesium deficiency, treating constipation, or general supplementation — magnesium glycinate or citrate work just as well at a fraction of the cost

You're using it for migraine prevention — magnesium oxide or citrate are the forms with actual prevention-trial data

You're hoping to prevent or treat Alzheimer's disease — the human data don't support this claim

You're already on calcium-channel blockers, bisphosphonates, or tetracyclines — magnesium has interactions to manage regardless of form

You want the cheapest magnesium for daily wellness use

Evidence at a glance

Goal	Effect	Best fit	Time
Brain magnesium concentration (mechanism) Good Evidence	Animal: ~15% rise in CSF magnesium vs no rise with magnesium chloride/citrate/gluconate at equivalent elemental Mg doses. Human CSF data: none.	Anyone whose decision is informed by mechanism plus modest human evidence	Hours in animal models; not measured in humans
Cognitive function in older adults with subjective decline Limited Evidence	Liu 2016: significant improvement in overall cognitive ability vs placebo; effect sizes moderate (g ≈ 0.5–0.8 on executive-function subscores); n=44	Adults 50+ with mild subjective cognitive complaints; otherwise healthy	6–12 weeks
Sleep quality Limited Evidence	Significant subjective improvement on PSQI and daytime function vs placebo at 21 days	Adults with mild self-reported sleep difficulties looking for a low-risk adjunct	Days to weeks
Anxiety / mood Mixed Evidence	No form-specific RCT data for MgT in anxiety or depression	No one specifically — generic magnesium is the more evidence-based pick for mood support	Not characterized
Alzheimer's disease prevention or treatment Weak Evidence	Encouraging animal-model results; no human disease-modification data	Researchers; people willing to act on preclinical signal	Not established in humans

Brain magnesium concentration (mechanism)

Good Evidence

Effect: Animal: ~15% rise in CSF magnesium vs no rise with magnesium chloride/citrate/gluconate at equivalent elemental Mg doses. Human CSF data: none.
Best fit: Anyone whose decision is informed by mechanism plus modest human evidence
Time: Hours in animal models; not measured in humans

Cognitive function in older adults with subjective decline

Limited Evidence

Effect: Liu 2016: significant improvement in overall cognitive ability vs placebo; effect sizes moderate (g ≈ 0.5–0.8 on executive-function subscores); n=44
Best fit: Adults 50+ with mild subjective cognitive complaints; otherwise healthy
Time: 6–12 weeks

Sleep quality

Limited Evidence

Effect: Significant subjective improvement on PSQI and daytime function vs placebo at 21 days
Best fit: Adults with mild self-reported sleep difficulties looking for a low-risk adjunct
Time: Days to weeks

Anxiety / mood

Mixed Evidence

Effect: No form-specific RCT data for MgT in anxiety or depression
Best fit: No one specifically — generic magnesium is the more evidence-based pick for mood support
Time: Not characterized

Alzheimer's disease prevention or treatment

Weak Evidence

Effect: Encouraging animal-model results; no human disease-modification data
Best fit: Researchers; people willing to act on preclinical signal
Time: Not established in humans

Evidence for 5 uses

AI-assisted evidence assessment — talk to your doctor before relying on any single supplement.

Brain magnesium concentration (mechanism)

Mechanism only

Good Evidence

The mechanistic case for MgT rests on a 2010 Neuron paper showing that in rats, oral MgT — uniquely among magnesium forms tested — raised cerebrospinal-fluid magnesium by ~15%, increased hippocampal NMDA receptor signaling, and improved learning and memory performance. The mechanism is plausible: threonate may act as a chaperone facilitating Mg²⁺ transport across the blood-brain barrier. Direct CSF measurement in humans on MgT has NOT been published — this is the gap between the mouse mechanism and the clinical claims.

Effect size

Animal: ~15% rise in CSF magnesium vs no rise with magnesium chloride/citrate/gluconate at equivalent elemental Mg doses. Human CSF data: none.

Time to effect

Hours in animal models; not measured in humans

Best fit

Anyone whose decision is informed by mechanism plus modest human evidence

Less likely

Anyone needing demonstrated human BBB-penetration evidence

Bottom line: The mechanism is real in animals. We don't have human CSF data confirming it translates. Decide accordingly.

SourceSlutsky et al., 2010 — Neuron

Cognitive function in older adults with subjective decline

Supplement benefit

Limited Evidence

The 2016 Liu trial in 44 adults aged 50–70 with subjective cognitive impairment found that 12 weeks of MgT (1.5–2 g/day) improved global cognitive scores vs placebo, with the largest effects in executive function and episodic memory. Effect sizes were moderate but the trial was small. A 2024 RCT (Hausenblas) showed improvements in sleep that may indirectly support cognition. Replication in larger independent trials is still limited; some published studies have manufacturer funding.

Effect size

Liu 2016: significant improvement in overall cognitive ability vs placebo; effect sizes moderate (g ≈ 0.5–0.8 on executive-function subscores); n=44

Time to effect

6–12 weeks

Best fit

Adults 50+ with mild subjective cognitive complaints; otherwise healthy

Less likely

Diagnosed Alzheimer's disease (no prevention or treatment benefit demonstrated); young adults with normal cognition

Bottom line: Promising in small trials but undersized and undermined by funding bias. Worth a 12-week trial if cognition is your specific goal; not a slam dunk.

Evidence is mixed

Most positive human trials are small (n ≤50) and several have ties to the patent-holding manufacturer. Independent large-scale replication is limited.

SourceLiu et al., 2016 — Journal of Alzheimer's Disease· conflicting

SourceLiu et al., 2016 — Journal of Alzheimer's Disease

Sleep quality

Supplement benefit

Limited Evidence

A 2024 RCT (Hausenblas, n=80) found 1 g nightly of magnesium L-threonate for 21 days improved subjective sleep quality, sleep efficiency, restorative sleep, and daytime functioning vs placebo in healthy adults with self-reported sleep concerns. The trial was relatively short and used subjective endpoints (PSQI, daytime function questionnaires) rather than polysomnography. Other magnesium forms (glycinate especially) have similar emerging sleep evidence.

Effect size

Significant subjective improvement on PSQI and daytime function vs placebo at 21 days

Time to effect

Days to weeks

Best fit

Adults with mild self-reported sleep difficulties looking for a low-risk adjunct

Less likely

Diagnosed insomnia or sleep apnea (use evidence-based therapy first)

Bottom line: Modest subjective sleep benefit. Magnesium glycinate is cheaper and has overlapping evidence; choose threonate only if you want the cognitive-evening dosing rationale.

SourceHausenblas et al., 2024 — Sleep Medicine: X

Anxiety / mood

Mechanism only

Mixed Evidence

No high-quality RCTs have tested MgT specifically for anxiety or depression. Magnesium more broadly has emerging RCT evidence in mild-to-moderate depression and anxiety, but the form-specific case for threonate over cheaper magnesium forms is mechanistic only. If you want magnesium for mood, you can save money with glycinate.

Effect size

No form-specific RCT data for MgT in anxiety or depression

Time to effect

Not characterized

Best fit

No one specifically — generic magnesium is the more evidence-based pick for mood support

Less likely

Anyone expecting threonate to outperform cheaper magnesium forms for mood

Bottom line: Use cheaper magnesium for mood support. Threonate's price premium is for cognition, not anxiety.

SourceSlutsky et al., 2010 — Neuron

Alzheimer's disease prevention or treatment

Mechanism only

Weak Evidence

Animal models of Alzheimer's pathology have shown MgT can reduce amyloid pathology and improve cognitive performance. There are NO human RCTs of MgT in clinically diagnosed Alzheimer's disease or mild cognitive impairment (MCI) showing slowed progression. Marketing that implies prevention or treatment is overstated.

Effect size

Encouraging animal-model results; no human disease-modification data

Time to effect

Not established in humans

Best fit

Researchers; people willing to act on preclinical signal

Less likely

Anyone expecting demonstrated Alzheimer's prevention or treatment

Bottom line: Don't pay a premium for unproven Alzheimer's prevention claims.

SourceSlutsky et al., 2010 — Neuron

How it works

Like other magnesium forms, magnesium L-threonate provides elemental magnesium to support hundreds of enzymatic reactions involved in energy metabolism, neuromuscular function, and protein synthesis. What sets it apart is preclinical evidence that the threonate carrier may facilitate transport across the blood-brain barrier, raising magnesium concentrations in cerebrospinal fluid more effectively than other forms in animal studies. In rodent studies, magnesium L-threonate increased brain magnesium levels and was associated with improvements in synaptic density, NMDA receptor function, and various measures of learning and memory. Whether these brain-specific effects also occur in humans at typical supplement doses remains uncertain, but the form is widely used for cognitive and sleep support based on this mechanism. The elemental magnesium content of magnesium L-threonate is relatively low (about 7-8% by weight), so larger total doses are needed to deliver the same elemental magnesium as other forms.

How to take it

1. Typical dose

• 1.5–2 g of magnesium L-threonate per day (~144 mg elemental magnesium total) • Most common product: 1,000 mg capsules — typical regimen 1 capsule with breakfast + 2 capsules in the evening • For sleep-only use: 1 g nightly 1–2 hours before bed • Stay at or below the 350 mg/d supplemental magnesium UL (elemental magnesium from all forms combined)

2. Higher studied dose

Liu 2016 used up to 2 g/day of MgT (~190 mg elemental Mg) for 12 weeks. Doses above this haven't been studied for additional benefit and risk approaching the 350 mg/d supplemental magnesium UL when combined with other sources.

3. Timing

Two-thirds of the day's dose is often taken in the evening because of the cognitive/sleep rationale. Some users dose entirely at bedtime. Take with food if you experience any GI sensitivity.

4. With food

Optional; food is not required but reduces GI upset for sensitive users.

5. Split dosing

Typical protocol splits the daily total: smaller morning dose + larger evening dose. Single-evening dosing is also used, especially for the sleep indication.

6. How long to try

Cognitive trials run 12 weeks — give it at least that long before judging cognitive effects. Sleep effects appear within days. Long-term safety beyond 12 weeks is poorly studied but no specific signals.

What to track

Subjective cognitive function (memory, focus, mental clarity) — give 8–12 weeks before judging

Sleep quality (PSQI-style or simple bedtime/wake-time + restfulness rating)

GI tolerance — threonate is gentler than oxide/citrate but still magnesium

Total elemental magnesium intake from all supplements (stay ≤350 mg/d added)

Bottom line: Take 1.5–2 g/day split AM/PM (or all PM for sleep). Give it 12 weeks for cognitive endpoints. If you don't notice anything, switch back to cheaper magnesium glycinate.

4 commercial forms

Compare the main delivery options and what they’re best suited for.

Magnesium L-threonate (Magtein, the standard branded form)

Brain-targeted form

A chelate of magnesium with L-threonic acid, developed by MIT researchers and licensed as Magtein. Animal data show selective BBB penetration; small human trials show modest cognitive and sleep benefits. The form-specific use case is cognition.

Standard absorption; the selling point is brain penetration, not gut absorption.

Magnesium glycinate (for cheaper sleep/relaxation use)

Cheaper alternative

Mg bound to glycine. Well-absorbed, gentle on the gut, emerging sleep and relaxation evidence. If you want magnesium for sleep at lower cost, this is the typical pick.

Excellent absorption; gentle GI profile.

Magnesium citrate (for general use or constipation)

Cheap and well-absorbed

Mg bound to citric acid. Well-absorbed; commonly used for general repletion. Higher doses are mildly laxative — useful or annoying depending on goal.

Well absorbed; mild laxative at higher doses.

Magnesium oxide (avoid for serious supplementation)

Inexpensive but poor absorption

Common in cheap multivitamins. Poorly absorbed (~4%); mostly laxative. Don't use as your only magnesium source if you're trying to raise body stores.

Low absorption; useful primarily as a laxative.

Safety

Know the common side effects, key cautions, and who should avoid it.

Common side effects

mild GI upset (less than oxide/citrate)occasional headacheloose stools at higher doses

Serious risks

Like any magnesium supplement, intake above the 350 mg/d elemental-Mg supplemental UL can cause persistent diarrhea, abdominal cramps, and at very high doses (grams of elemental Mg) hypermagnesemia with hypotension and cardiac effects — especially in people with reduced kidney function.
SourceNIH Office of Dietary Supplements — Magnesium — Health Professional Fact Sheet
Severe hypermagnesemia is rare in people with normal kidney function but is a serious risk in chronic kidney disease — even modest supplemental doses can accumulate.
SourceNIH Office of Dietary Supplements — Magnesium — Health Professional Fact Sheet

Who should avoid it

People with chronic kidney disease (eGFR <30) — magnesium clearance is impaired; supplemental magnesium of any form risks hypermagnesemia. Talk to your nephrologist.
SourceNIH Office of Dietary Supplements — Magnesium — Health Professional Fact Sheet
People with bradycardia, AV block, or myasthenia gravis — magnesium can worsen these conditions at high serum levels.
SourceNIH Office of Dietary Supplements — Magnesium — Health Professional Fact Sheet
Anyone with bowel-obstruction risk or severe IBD flare — high magnesium can exacerbate diarrhea.

Pregnancy & breastfeeding

Magnesium in pregnancy at RDA levels (350–360 mg/d total, food + supplement) is safe and beneficial. Magnesium L-threonate specifically has not been studied in pregnant women; if you want supplemental magnesium during pregnancy, stick to better-studied forms (glycinate, citrate) at standard prenatal doses. Don't use MgT-specific high-cognitive-dose regimens (1.5–2 g/day) in pregnancy without your obstetrician's input.

SourceNIH Office of Dietary Supplements — Magnesium — Health Professional Fact Sheet

Bottom line: MgT shares magnesium's overall safety profile. Stay at or under 350 mg/d elemental Mg from supplements. Skip in advanced kidney disease.

Interactions

tetracycline antibiotics (doxycycline, minocycline) and quinolones (ciprofloxacin)Moderate

Magnesium binds these antibiotics in the gut and dramatically reduces their absorption. Separate dosing by 2 hours before or 4–6 hours after magnesium.

SourceNIH Office of Dietary Supplements — Magnesium — Health Professional Fact Sheet

bisphosphonates (alendronate, risedronate)Moderate

Magnesium reduces absorption of oral bisphosphonates. Take bisphosphonate first, wait at least 30 minutes (preferably 2 hours), then take magnesium.

SourceNIH Office of Dietary Supplements — Magnesium — Health Professional Fact Sheet

proton pump inhibitors (omeprazole, pantoprazole) — long-term useModerate

Long-term PPI use (>1 year) lowers magnesium absorption and can cause hypomagnesemia. People on chronic PPIs may need a magnesium supplement, but should also monitor levels.

SourceNIH Office of Dietary Supplements — Magnesium — Health Professional Fact Sheet

diuretics — loop (furosemide) and thiazideMinor

These diuretics increase urinary magnesium losses, sometimes warranting supplementation; potassium-sparing diuretics conversely reduce magnesium losses.

SourceNIH Office of Dietary Supplements — Magnesium — Health Professional Fact Sheet

Protocols featuring Magnesium threonate

Evidence-backed routines where Magnesium threonate plays a role.

Deep Sleep & Recovery

sleep

Slow-wave (deep) sleep is when growth hormone peaks, memory consolidates, and tissue recovery accelerates. Some people sleep 8 hours but get insufficient deep sleep — often visible in poor next-day recovery, brain fog, and slow gains from training. This stack targets deep sleep architecture specifically: apigenin and magnesium L-threonate (crosses blood-brain barrier better than other forms), glycine for slow-wave enhancement, L-theanine for alpha-wave priming, and zinc for testosterone-mediated sleep architecture support.

Choosing a product

What to look for on the label — and what to be skeptical of.

Look for…

Look for the 'Magtein' branded ingredient — this is the patented form used in the published cognitive trials

Label should state both magnesium L-threonate weight AND elemental magnesium content per serving

Daily serving providing 1.5–2 g MgT (~144–190 mg elemental Mg) matches the cognitive trial dosing

Third-party tested (USP, NSF, Informed Choice)

Single-ingredient products (or simple stacks) make it easier to dose precisely

Be skeptical of…

'Crosses the blood-brain barrier' as a unique selling point — this is animal data; not directly demonstrated in humans

'Prevents Alzheimer's' or 'reverses cognitive decline' — no human disease-modification trials exist

'Best magnesium for every use' — for non-brain magnesium needs, cheaper forms work as well

Marketed as a sleep aid at a price premium — magnesium glycinate has overlapping evidence for less money

'Boosts brain magnesium 50%' or similar specific percentage claims — those numbers come from animal studies, not human CSF measurements

Frequently asked questions

Is magnesium threonate really better for the brain?⌄

Animal studies clearly show it raises brain magnesium levels more than other forms. Human evidence is limited but suggestive. If brain effects are your goal, it is a reasonable choice; for muscle, sleep, or constipation, other forms work as well or better.

How much elemental magnesium am I getting?⌄

Magnesium L-threonate is only about 7-8% elemental magnesium. A 2,000 mg dose provides roughly 144-160 mg of elemental magnesium, less than the same weight of magnesium citrate or oxide.

When should I take it?⌄

Many users take a smaller dose in the morning and a larger dose 1-2 hours before bed to support sleep and overnight brain magnesium delivery.

Can I combine it with other magnesium?⌄

Yes, but watch total elemental magnesium intake. Keep total supplemental magnesium under 350 mg/day unless directed by a clinician.

Is it worth the price?⌄

Magnesium L-threonate is significantly more expensive than other magnesium forms. If you specifically want brain-targeted dosing for cognition or sleep, it may be worthwhile. For general magnesium support, cheaper forms work fine.

References by claim

Brain magnesium concentration (mechanism)

Slutsky et al., 2010 — Neuron (2010) link

Cognitive function in older adults with subjective decline

Liu et al., 2016 — Journal of Alzheimer's Disease (2016) link

Sleep quality

Hausenblas et al., 2024 — Sleep Medicine: X (2024) link

Safety

NIH Office of Dietary Supplements — Magnesium — Health Professional Fact Sheet (2024) link

Other references

Magnesium threonate on Wikidata — Wikidata link

Magnesium threonate (PubChem CID 71307398) — PubChem link

Magnesium threonate on NIH DSLD — NIH Dietary Supplement Label Database link

Track Magnesium threonate with Pilora

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Evidence-based·Last reviewed May 31, 2026·Evidence current as of May 31, 2026·How we grade evidence

Disclaimer: These statements have not been evaluated by the FDA. This page is educational, not a substitute for personalized medical advice. Evidence grades are AI-assisted assessments — talk to your doctor before starting any new supplement, especially if you’re pregnant, breastfeeding, on medications, or managing a chronic condition.