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Magnesium L-Threonate illustration

Strongest sleep-Mg evidence

Magnesium L-Threonate

The only magnesium form with mechanistic evidence for raising brain magnesium levels. Sleep-quality and cognitive trials are recent, small, and largely industry-funded.

Minerals Last verified 2026-05-06
sleep stress and mood

Why this matters

Magnesium L-Threonate is the only magnesium form developed specifically as a brain-targeted compound. It was synthesized at MIT in the late 2000s by Liu and colleagues, who showed in rodent work that L-threonate (the sugar acid bound to the magnesium ion) shuttles magnesium across the blood-brain barrier substantially more efficiently than common forms like oxide, citrate, or glycinate. The branded extract sold under the Magtein label is produced by Magceutics under license; nearly every reputable consumer product on the market traces back to that same upstream supply. The mechanistic rationale is clean and the rodent data on synaptic plasticity is striking. The human evidence is thinner: the largest published trial (Liu et al. 2016) ran a small sample of older adults on 1.5-2g Magtein daily for 12 weeks and saw cognitive-aging gains, with later replications in smaller cohorts. Treat the supplement as a targeted intervention for cognitive aging or sleep-quality concerns, not a substitute for overall magnesium status. If you are deficient in magnesium generally, addressing that with a cheaper form (glycinate, citrate) is the larger lever. If you are sufficient and looking for a brain-specific add-on, Magtein is the form with the most defensible mechanism.

What it does

Magnesium L-Threonate (Magtein) crosses the blood-brain barrier via threonate-glucose-transporter coupling, mechanistically distinct from glycinate or citrate. Recent RCTs at 1 to 2 g/day show sleep-quality improvement; cognitive trials are smaller and mixed.

What works

  • 1.5-2g daily of Magtein-branded extract, divided into AM and evening doses, taken with food.
  • 12-week minimum trial duration. The Liu 2016 endpoint was at week 12; shorter periods read as null.
  • Pairing with sleep-hygiene baseline. The evening dose's effect on slow-wave sleep is one of the more reliable subjective signals.
  • Distinguishing Magtein from generic 'magnesium L-threonate'. Some products use cheaper non-branded threonate with unverified bioavailability.

What doesn't

  • Treating Magtein as a one-to-one substitute for elemental magnesium needs. Per gram, it delivers ~7% elemental Mg, much less than oxide (~60%) or glycinate (~14%).
  • Sub-1g daily doses. Below the trial baseline, you are extrapolating from animal data only.
  • Expecting acute single-dose nootropic effects. The compound's clinical signal is structural over weeks, not a same-day cognitive lift.

Top picks

  1. 1

    Life Extension

    Neuro-Mag Magnesium L-Threonate

    Magtein-branded; ~144 mg elemental Mg per 3-cap serving (matches Hausenblas 2024).

    Check on Amazon
  2. 2

    Jarrow Formulas

    MagMind Magnesium L-Threonate

    Magtein 2,000 mg per serving.

    Check on Amazon
  3. 3

    Doctor's Best

    Brain Magnesium with Magtein

    150 mg elemental Mg per 3-cap serving.

    Check on Amazon

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How to use it

Dosage
1.5 to 2 g/day Magtein (~144 mg elemental Mg at 2 g).
Timing
Split: majority in evening 1 to 2 hours before sleep for sleep benefit; morning portion for daytime cognition.
With food
Not required
Onset
Sleep changes 1 to 3 weeks; cognitive gains 4 to 12 weeks.

What to look for

  • Magtein-branded on the label (only patented form has clinical data).
  • Elemental Mg labeling disclosed (Magtein is ~7-8% elemental, vs glycinate ~14% or citrate ~16%).
  • Capsule count at 90 caps for 30 days at the 3-cap clinical dose.
  • Pair with glycinate if also targeting systemic Mg deficiency; Magtein's value is BBB penetration, not RDA coverage.
  • Third-party tested (USP, NSF, ConsumerLab).

Formats: capsules.

Skip if:
  • Renal impairment or CKD (hypermagnesemia and arrhythmia risk).
  • Concurrent bisphosphonates, tetracyclines, quinolones, or levothyroxine (Mg chelates these; separate by 2 to 4 hours).
  • Myasthenia gravis (Mg potentiates neuromuscular weakness).

FAQ

Worth the premium over glycinate?
If your goal is brain effects (sleep quality, cognition), the BBB penetration story is real; that justifies the premium. For general magnesium repletion, glycinate at half the price is fine.

Suggested protocol

Twice-daily Magtein for cognitive aging or sleep support

Split the daily dose AM and evening. The evening portion is what most users report on subjectively (sleep depth, morning clarity); the AM portion supports total daily intake without an evening overdose.

  • Magtein (magnesium L-threonate) 1g (~144mg Magtein) AM + 1g evening

    Timing: AM with breakfast, evening 1-2 hours before bed

    Verify Magtein branding on the label. Re-evaluate at week 12.

  • Background magnesium check Diet + optional 200mg elemental glycinate if intake is low

    Timing: Any meal

    Magtein does not replace overall magnesium sufficiency. Address general intake first if it is the actual gap.

Additional references