Comparison
Magnesium L-Threonate vs Melatonin
Side-by-side of Magnesium L-Threonate and Melatonin. Every row below is pulled from the compound schema and will update as our data grows. For deeper reads, follow through to each compound page.
Magnesium L-Threonate
Magnesium l-threonate (Magtein) crosses the blood-brain barrier. Typical dose 1,500-2,000 mg. Sleep and cognitive trial data, side effects.
Melatonin
Melatonin as a sleep supplement: 0.3-1 mg matches physiological output, 3-10 mg is pharmacological. Shifts circadian phase, shortens sleep latency.
Effects at a glance
Magnesium L-Threonate
- •Distinct magnesium salt designed for blood-brain barrier penetration; not a higher-quality systemic magnesium
- •Liu 2010 rodent study: elevated CSF magnesium ~15% and increased hippocampal synaptic density
- •Trial portfolio in humans is small and mostly Magtein-funded; cognitive effects are modest where reported
- •Typical dose 1500 to 2000 mg/day delivers only ~108 to 144 mg of elemental magnesium
- •GI tolerability comparable to other magnesium forms; loose stools in a minority at 2000 mg/day
- •Distinct from magnesium glycinate, which is the conventional sleep/anxiety/repletion form
Melatonin
- •Shortens sleep onset latency by ~7 to 12 minutes at physiological 0.3 to 1 mg doses
- •Advances circadian phase when taken 30 to 60 minutes before target bedtime, useful for jet lag and shift work
- •Does not meaningfully increase total sleep time in healthy adults without circadian misalignment
- •Endogenous nighttime production is not suppressed by short-term exogenous supplementation
- •Higher doses (3 to 10 mg) raise plasma levels above physiological range and often increase morning grogginess
- •Effective for delayed sleep-wake phase disorder and reducing jet-lag severity in eastward travel
Side-by-side
| Attribute | Magnesium L-Threonate | Melatonin |
|---|---|---|
| Category | supplement | supplement |
| Also known as | Mg-T, MgT, Magtein, magnesium threonate | N-acetyl-5-methoxytryptamine |
| Half-life (hr) ↗ | 4 | 0.75 |
| Typical dose (mg) ↗ | 2000 | 0.5 |
| Dosing frequency | 1 to 3 times daily | daily, 30 to 60 minutes before target sleep time |
| Routes | oral | oral, sublingual |
| Onset (hr) | 1 | 0.5 |
| Peak (hr) | 2 | 1 |
| Molecular weight | 294.5 | 232.28 |
| Molecular formula | C8H14MgO10 | C13H16N2O2 |
| Mechanism | Proposed to deliver magnesium across the blood-brain barrier more effectively than other oral salts via threonate-related transporters, raising CNS magnesium and modulating NMDA receptor function and synaptic plasticity. | Agonist at MT1 and MT2 receptors in the suprachiasmatic nucleus, signaling biological night and promoting sleep-onset gating plus circadian phase shifts. |
| Legal status | OTC dietary supplement | OTC in US; prescription in UK, EU, Japan |
| WADA status | allowed | allowed |
| DEA / Rx | OTC supplement (not scheduled) | OTC supplement in US; Rx in UK, EU, Japan, Australia |
| Pregnancy | Standard magnesium safety; Mg-T-specific data limited | Insufficient data; not routinely recommended |
| CAS | 778571-57-6 | 73-31-4 |
| PubChem CID | 10691810 | 896 |
| Wikidata | Q27151568 | Q179243 |
Safety profile
Magnesium L-Threonate
Common side effects
- loose stools
- mild GI upset
- headache (rare)
- fatigue (rare)
Contraindications
- severe renal impairment (eGFR below 30)
- hypermagnesemia
- myasthenia gravis (high doses)
- concurrent IV magnesium therapy
Interactions
- tetracyclines and fluoroquinolones: magnesium chelation reduces antibiotic absorption; separate by 2 to 4 hours(moderate)
- bisphosphonates: reduced absorption; separate by 2 hours minimum(moderate)
- muscle relaxants and aminoglycosides: potentiated neuromuscular blockade at high doses(moderate)
- antihypertensives: additive blood pressure reduction at high doses(minor)
Melatonin
Common side effects
- vivid dreams
- morning grogginess (higher doses)
- headache
- dizziness
Contraindications
- autoimmune disease (theoretical)
- concurrent anticoagulant therapy without monitoring
Interactions
- fluvoxamine: CYP1A2 inhibition raises melatonin levels substantially(major)
- warfarin: possible increased bleeding risk(moderate)
- benzodiazepines and alcohol: additive sedation(moderate)
- antihypertensives: may alter blood pressure response(minor)
Which Should You Take?
Melatonin comes out ahead for most readers on the criteria we weight: 2 catalogued goals, OTC, oral dosing, with a Tier-A outcome catalogued. Magnesium L-Threonate is the right call when one of the conditionals below applies.
- → If your priority is focus or working memory, pick Magnesium L-Threonate.
- → If your priority is circadian regulation, pick Melatonin.
- → If your priority is sleep onset or sleep quality, pick Melatonin.
Edge case: Half-lives differ materially (Magnesium L-Threonate ~4 hr vs Melatonin ~0.75 hr). Magnesium L-Threonate reaches steady state faster; Melatonin is easier to dial in if tolerability is uncertain.
Default choice: Melatonin. Wider use case, a Tier-A evidence outcome catalogued, and broader goal coverage. Reach for Magnesium L-Threonate only if your priority sits squarely in the goals it owns above.
This verdict is generated from each compound's schema (goals, legal status, evidence outcomes, dosing route). It updates automatically as our compound data evolves; the deeper read sits on each individual compound page.
Common questions
What is the difference between Magnesium L-Threonate and Melatonin?
Magnesium L-Threonate and Melatonin differ in category (supplement vs supplement), mechanism, and typical dosing. See the side-by-side table for full details.
Which has a longer half-life, Magnesium L-Threonate or Melatonin?
Magnesium L-Threonate half-life is 4 hours; Melatonin half-life is 0.75 hours.
Can you stack Magnesium L-Threonate with Melatonin?
Stack compatibility depends on mechanism overlap, legal status, and individual response. Check each compound page for specific interactions and contraindications before combining.
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