mineral · for brain fog
Magnesium L-Threonate
The one form of magnesium that reaches the brain, where it strengthens cell connections.
Say that in clinical terms
Magnesium L-threonate (MgT) uniquely crosses the blood-brain barrier, increasing brain magnesium concentrations. This enhances synaptic density, NMDA receptor signaling, and long-term potentiation in the prefrontal cortex and hippocampus.
How strong is the research?
In 109 breast cancer patients after surgery, 12 weeks produced no improvement in pain, sleep or mood.
3 papers read, 2 supporting, 1 against.
Who was studied: Adults aged 50 to 70 with assessed cognitive impairment, not healthy adults feeling foggy.
How much to take
daily (split AM/PM)
1000–2000 mg
Take with or without food. The 2000mg dose provides ~144mg elemental magnesium. Allow 4-6 weeks for full cognitive effects.
Before you take it
- NIH ODS Tolerable Upper Intake Level is 350 mg/day of supplemental magnesium for adults (all magnesium salt forms combined); the limiting adverse effect used to set this level was diarrhea.
- Kidney disease: the kidneys clear excess magnesium; impaired renal function (chronic kidney disease) substantially increases risk of hypermagnesemia. Medical supervision required for any CKD patient taking supplemental magnesium.
- Antibiotic interaction: magnesium forms insoluble complexes with tetracyclines (e.g., doxycycline) and fluoroquinolones (e.g., ciprofloxacin), reducing antibiotic absorption. Per NIH ODS: take antibiotics at least 2 hours BEFORE or 4–6 hours AFTER magnesium supplements.
- Bisphosphonate interaction: magnesium reduces absorption of bisphosphonates (e.g., alendronate/Fosamax); separate doses by at least 2 hours.
- Diuretic interaction: loop and thiazide diuretics increase urinary magnesium excretion; potassium-sparing diuretics reduce excretion — clinical monitoring of serum magnesium is warranted.
- Proton pump inhibitor (PPI) interaction: long-term PPI use (>1 year) can itself cause hypomagnesemia; the FDA recommends monitoring serum magnesium levels in patients on chronic PPIs who also take magnesium supplements.
- The L-threonate carrier produces less osmotic GI/laxative effect than magnesium citrate or oxide at equivalent elemental magnesium doses, but gastrointestinal discomfort remains possible above the UL.
- Pregnancy and breastfeeding: the standard supplemental magnesium UL applies; physician consultation recommended before use.
When to take it
Best taken: evening