Mineral
Magnesium L-Threonate
Moderate EvidenceThe form is specifically studied for raising brain magnesium in animal work, and a small number of human trials report cognitive effects; the evidence is far lighter than for magnesium repletion generally, hence Moderate. The human trials, one by one: in 44 adults aged 50–70 with cognitive complaints plus sleep or anxiety problems, MMFS-01 — a threonate compound trademarked ClariMem, tested by the company that developed it — at 1.5–2 g a day (about 25 mg/kg) for 12 weeks improved a composite cognitive score against placebo with a large effect size (d=0.91), while its effects on sleep and anxiety were hidden by strong placebo responses (Liu 2016). In 80 adults aged 35–55 with self-reported sleep problems, 1 g a day for 21 days kept sleep quality and daytime functioning steady while the placebo group's declined, with better Oura-ring deep- and REM-sleep scores (Hausenblas 2024). A 30-day trial in 109 healthy Chinese adults gave threonate combined with phosphatidylserine and vitamins C and D, so it cannot say what the magnesium did alone (Zhang 2022). Compared with magnesium glycinate, threonate has the more specific brain story but far less human outcome data and less magnesium per capsule; compared with citicoline for memory, its trial base is smaller and younger. Verdict: a reasonable experiment if you want a brain-targeted magnesium and accept that the human evidence is three small, short trials, at least one run by the compound's developer; if the goal is simply to correct low magnesium, glycinate does that with fewer capsules.
Recommended Dose
2000 mg (providing ~144 mg elemental Mg) daily
Timing
Evening, split into 2 doses
Mechanism of Action
Magnesium L-threonate (MgT) is magnesium bound to threonic acid, a compound developed specifically to raise magnesium inside the brain. The evidence that it does so is in rats: MgT raised brain magnesium, increased synapse density in the hippocampus and improved learning, working memory and short- and long-term memory in young and aged animals (Slutsky 2010). In the one placebo-controlled human trial of the threonate compound on its own, the developers tracked red-blood-cell magnesium as their marker of uptake rather than measuring brain levels (Liu 2016). Each 2,000 mg supplies only about 144 mg of elemental magnesium, so it is a small magnesium dose in a large capsule count.
Side Effects & Safety
Headache, drowsiness, or GI upset. Lower elemental magnesium per capsule means more pills needed. More expensive than other forms. Avoid in significant kidney impairment, exactly as with any magnesium salt.
Do not use / talk to a doctor first
- Chronic kidney disease or any significant renal impairment - it is still magnesium, cleared by the same route
- Heart block or myasthenia gravis, without medical advice
Interactions
Tetracycline antibiotics (doxycycline, demeclocycline)
Magnesium forms insoluble complexes with them, reducing absorption of the antibiotic. Separate the doses
Source: NIH Office of Dietary Supplements, Magnesium
Quinolone antibiotics (ciprofloxacin, levofloxacin)
Same insoluble-complex problem as tetracyclines. Separate the doses
Source: NIH Office of Dietary Supplements, Magnesium
Oral bisphosphonates (e.g. alendronate)
Magnesium reduces their absorption. Take magnesium at least 2 hours before or after the bisphosphonate
Source: NIH Office of Dietary Supplements, Magnesium
Anything that impairs kidney function
Magnesium is cleared renally. When clearance falls, supplemental magnesium accumulates and hypermagnesemia becomes possible - this, not the upper intake level, is the real hazard
Source: NIH Office of Dietary Supplements, Magnesium
Pregnancy & breastfeeding
Not specifically studied in pregnancy in this form. Magnesium itself is used in pregnancy, but agree any supplement with a midwife or doctor.
Who should avoid / see a doctor
Anyone with reduced kidney function - this entry previously carried no renal caution while the glycinate entry did, which was inconsistent: it is the same mineral cleared the same way. At roughly 144 mg elemental magnesium the dose here sits well under the 350 mg/day supplemental upper intake level, so the tolerability concern is smaller than for high-dose forms; the renal one is identical.
Synergies
Used in These Stacks
See Magnesium L-Threonate inside a full protocol — the stack pages cover when and why to combine it.
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References
- 1.NIH Office of Dietary Supplements, Magnesium - Health Professional Fact Sheet — The tolerable upper intake level for SUPPLEMENTAL magnesium in adults is 350 mg/day. Toxicity risk rises with impaired renal function; signs generally appear once serum concentrations exceed 1.74-2.61 mmol/L. Magnesium forms insoluble complexes with tetracyclines and quinolones and reduces bisphosphonate absorption. (authoritative body)
- 2.Costello 2023, Advances in Nutrition — The 350 mg/day UL was set in 1997 with diarrhea as the limiting factor. Reviewing intervention studies from 1997-2022, seven studies at intakes of 128-1200 mg/day found no significant difference in diarrhea between intervention and control, and an FDA CAERS search found only 40 attributable gastrointestinal adverse-event cases; the authors conclude the UL should be re-evaluated. (perspective / evidence review)
- 3.Slutsky 2010, Neuron — Rats: magnesium-L-threonate raised brain magnesium and improved learning, working memory and short- and long-term memory, with pattern completion improved in aged rats; hippocampal synaptic-puncta density rose and correlated with memory improvement. (animal study — the origin of the brain-magnesium claim)
- 4.Liu 2016, J Alzheimers Dis — 44 adults aged 50–70 with cognitive impairment, randomised double-blind: MMFS-01 (an L-threonic acid magnesium salt compound, ClariMem) at about 25 mg/kg/day (1.5–2 g/day) vs placebo for 12 weeks improved overall cognitive ability (p=0.003, Cohen's d=0.91); effects on sleep and anxiety could not be determined because of strong placebo effects; adverse events mostly mild, none serious. (run by the compound's developer (Neurocentria); dosing and composition from the full text, PMC4927823)
- 5.Hausenblas 2024, Sleep Med X — 80 adults aged 35–55 with self-reported sleep problems, randomised double-blind: magnesium L-threonate 1 g/day for 21 days maintained sleep quality and daytime functioning while placebo declined; improved Oura-ring deep and REM sleep scores and morning behaviour, energy, mood and alertness ratings versus placebo; well tolerated. (three of six authors list AIDP as their affiliation; a corrigendum was published in 2025)
- 6.Zhang 2022, Nutrients — 109 healthy Chinese adults aged 18–65, double-blind: 2 g/day of Magtein PS (magnesium L-threonate + phosphatidylserine + vitamins C and D) for 30 days improved all five Clinical Memory Test subscores versus placebo, more in older participants. (combined formula — cannot isolate the magnesium effect)
