Supplement analysis backed by scientific evidence · PT

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Limited evidenceBrain & cognition

Magnesium L-Threonate

A patented magnesium form marketed for memory and "brain magnesium" on the strength of rodent data and two small manufacturer-linked human trials. It is a perfectly fine magnesium salt, but the cognitive story is far ahead of the evidence — and it delivers very little elemental magnesium per dollar.

What the science says

  • Cognitive function in older adults Limited evidence

    The pivotal MMFS-01 trial randomized just 44 adults aged 50-70 with self-reported cognitive impairment to ~1.5-2 g/day magnesium L-threonate or placebo for 12 weeks, reporting improvement in a composite cognitive score and a large drop in an estimated "brain age" measure. The sample was tiny, dropout was substantial, and the study was designed and funded by the ingredient's developer. No independent replication in this population exists.

  • Memory and attention in healthy adults Limited evidence

    A 30-day trial in 109 healthy Chinese adults reported gains in memory and attention, but the product tested was a multi-ingredient formula containing magnesium L-threonate alongside other actives, so the effect cannot be attributed to the threonate itself. It was again run with manufacturer involvement.

  • Superior delivery of magnesium to the brain Limited evidence

    The central marketing claim — that L-threonate raises brain magnesium where other salts cannot — rests on rodent CSF and hippocampal measurements. No human study has demonstrated higher cerebrospinal fluid or brain magnesium in people taking it versus magnesium citrate or glycinate.

  • Sleep and anxiety Limited evidence

    Widely sold as a sleep and calm aid, but there is no dedicated randomized trial of magnesium L-threonate for insomnia or anxiety. Any benefit most likely reflects correcting a magnesium shortfall, which far cheaper forms do equally well.

Dosage & safety

Studied doseTrials used 1,500-2,000 mg/day of magnesium L-threonate, usually split into a morning and evening dose (evening dose larger). Note the low elemental magnesium content: about 8% by weight, so 2,000 mg of the compound supplies only ~144 mg of elemental magnesium — roughly a third of an adult RDA, at several times the price of magnesium citrate or glycinate.
SafetyGenerally well tolerated; reported effects are mild GI upset, headache, and daytime drowsiness. Standard magnesium cautions apply: avoid supplemental magnesium in severe renal impairment (eGFR <30) where clearance is impaired and hypermagnesemia can occur. Magnesium binds tetracycline and fluoroquinolone antibiotics and bisphosphonates — separate doses by at least 2 hours. Not a banned substance in sport. The main practical downside is cost per milligram of usable magnesium.

Scientific references

Where to buy

Life Extension, Neuro-Mag®, Magnesium L-Threonate, 90 Vegetarian Capsules (48 mg per Capsule)

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