Supplement

Magnesium L-ThreonateNew

Supplement

Minerals

4/10 Evidence

A brain-targeted magnesium salt (best known as Magtein) studied for cognition and sleep, marketed on its ability to raise brain magnesium; human data are limited and mostly industry-linked.

Mechanism of Action

L-threonate (a vitamin C metabolite) is proposed to enhance magnesium transport into the brain, supporting NMDA receptor modulation, synaptic density, and long-term potentiation; the brain-uptake advantage is supported by rodent data and limited human CSF data.

Dosing Protocol

Recommended

2000mg magnesium L-threonate per day (Magtein 2 g = about 144 mg elemental magnesium)

Standard starting dose based on research

Therapeutic Range

1000

Minimum

2000

Maximum

mg magnesium L-threonate per day (Magtein 2 g = about 144 mg elemental magnesium)

Divided doses, often 1 g in the morning and 1 g in the evening (evening dose for sleep)

Cycling Protocol

Studied for 6-12 weeks continuously; reassess after 3 months

Dosages are general guidelines. Individual requirements vary based on body weight, health status, and specific goals. Start with lower doses and adjust based on response.

Benefits

Primary Benefits

Cognitive performance support
Sleep-related impairment
Stress physiology (heart rate, HRV)

Secondary Benefits

Possible support for age-related memory decline

Supplemental magnesium repletion

Safety Information

Contraindications

Do not use if any of the following apply:

•Significant kidney impairment (reduced magnesium clearance)
•Myasthenia gravis
•Heart block or bradyarrhythmia without clinician guidance

Drug/Supplement Interactions

May interact with the following. Consult a healthcare provider before combining:

Antibiotics (tetracyclines, fluoroquinolones) — separate by 2-4 hours

Bisphosphonates — separate by 2 hours

Antihypertensives and calcium-channel blockers — possible additive effect

Levothyroxine — separate by 4 hours

Potential Side Effects

Some users may experience:

Loose stools or GI upset at higher doses

Drowsiness

Headache

Rare lightheadedness

This is not a complete list of interactions or side effects. Individual responses vary. Always start with the lowest effective dose and monitor your response. Report any adverse effects to your healthcare provider.

Quality Markers

Look for these specific quality indicators when sourcing this compound:

Branded Magtein (used in published trials) with stated elemental magnesium
Dose per serving of magnesium L-threonate (not total magnesium) disclosed
Third-party tested

Trusted Certifications

NSF Certified

USP Verified

GMP Certified

ConsumerLab Approved

Note: Supplement quality varies dramatically between brands. Cheap supplements often contain fillers, incorrect doses, or contaminants. Investing in quality products from reputable manufacturers is essential for safety and efficacy.

Evidence Profile

Evidence Score

4/10

Emerging/Anecdotal

Limited clinical data, primarily mechanistic studies or user reports

Classification:

Emerging/Moderate — a 2026 Frontiers in Nutrition RCT (n=100, adults 18-45 with poor sleep, 2 g/day Magtein for 6 weeks) found greater improvement in NIH Toolbox cognition composite and reaction time and in self-reported sleep-related impairment versus placebo, with no difference on most other sleep measures; earlier small RCTs in older adults support cognition, but trials are short, small, and largely linked to the patent holder, and no long-term or independent replication exists Evidence

Evidence Scale

8-10

Strong

5-7

Moderate

1-4

Emerging

PHS

671

/ 1000

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