Full profile
| Also known as | Magtein, Magnesium threonate, MgT |
|---|---|
| Best for | People specifically seeking the brain-marketed magnesium form (with realistic expectations) · General magnesium intake support · A calm/sleep-adjacent stack position |
| Evidence grade | Emerging — Emerging — mostly preclinical or preliminary human data |
| Studied dose range | ~1.5–2 g/day of magnesium L-threonate (delivering a relatively small amount of elemental magnesium) as used in the human trial. |
| Time to effect | Trials ran ~12 weeks; no reliable acute effect. |
| Best form | Magnesium L-threonate (Magtein) is the studied brain-marketed form; for general magnesium repletion, cheaper forms (glycinate, citrate) deliver more elemental magnesium per dose. |
| Food sources | The threonate form is synthetic; dietary magnesium: leafy greens, nuts, seeds, legumes, whole grains |
Evidence, honestly graded
The foundational work (Slutsky 2010, Neuron) is a rodent study showing raised brain magnesium improved learning and memory. Human data is thin: the MMFS-01 trial (Liu 2016, ~44 completers, developer-linked) reported cognitive improvement in older adults with complaints. This is single-small-trial and preclinical territory, not established human cognition benefit — general magnesium status is a separate, better-founded topic.
See the full grading rubric — study type, replication, population match, and dose adequacy — in The Evidence Standard.
Side effects
- Generally well tolerated
- Headache or drowsiness reported
- GI upset or loose stools (less than with oxide/citrate)
Who should avoid it or check first
- Kidney impairment (reduced magnesium clearance) without clinician oversight
- Pregnant or breastfeeding without clinician guidance
Interactions
- Can reduce absorption of some antibiotics (tetracyclines, quinolones) and bisphosphonates — separate the doses
- Additive with other magnesium sources — watch total elemental magnesium
Stacks well with
- L-Theanine
- Vitamin D3
- B-Complex (B6, B9, B12)
Use caution stacking with
- Other high-dose magnesium salts (cumulative laxative and elemental load)
What to look for on a label
- Always disclose elemental magnesium per serving, not just the threonate compound weight — the two differ substantially, and this is the most common way this ingredient is oversold.
- Health Canada's magnesium monographs cover mineral/electrolyte, muscle, and bone roles — not cognition; do not present threonate as a Health-Canada-recognized cognition ingredient, as a brain claim is off-monograph.
References
- Slutsky 2010, Neuron — brain magnesium and memory (preclinical). Rodent study; foundational mechanism, not human proof. PMID 20152124; doi:10.1016/j.neuron.2009.12.026. Educational.
- Liu 2016, J Alzheimers Dis — MMFS-01 human RCT. Small (~44 completers), developer-linked trial in older adults with cognitive complaints. PMID 26519439; doi:10.3233/JAD-150538. Educational, not a product claim.
Grades and studied doses are our conservative reading of the human research, shown for education. They are not product claims, and a studied dose is not a recommended dose.
See how Magnesium L-Threonate compares on grade, dose, and goal in the Evidence Explorer.