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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.

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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.

How to take it

TimingSplit morning and evening with the larger dose in the evening, as the trials did.
With food?With or without food; it is far less laxative than citrate or oxide because it carries so little elemental magnesium.
Worth knowingAt about 8% elemental magnesium, 2,000 mg of the compound gives you only ~144 mg of magnesium — if you are also trying to fix a magnesium deficiency, this is not the product for it.

Interactions

With medications

  • tetracycline and fluoroquinolone antibiotics

    Magnesium chelates these antibiotics and reduces their absorption. take the antibiotic at least 2 hours before or 4-6 hours after

  • bisphosphonates

    Absorption of the bisphosphonate is substantially reduced. separate by at least 2 hours

  • levothyroxine

    Magnesium reduces thyroid hormone absorption. separate by at least 4 hours

With other supplements

  • other magnesium supplements

    Elemental magnesium adds up across products, and the laxative threshold depends on your total. count elemental magnesium from every source, not capsule counts

Well-established interactions only — this is not a complete list. Always tell your doctor and pharmacist what you take.

Frequently asked questions

Does magnesium L-threonate improve memory?

The evidence is limited. The key trial randomized just 44 adults and was funded by the ingredient's developer, and no independent study has replicated the cognitive benefit of magnesium L-threonate.

Does magnesium L-threonate get more magnesium into the brain?

That claim rests on rodent data. No human study has shown higher brain or spinal fluid magnesium with magnesium L-threonate than with magnesium citrate or glycinate.

How much magnesium L-threonate per day?

Trials used 1,500–2,000 mg/day of magnesium L-threonate, split morning and evening with the larger dose at night. That supplies only about 144 mg of elemental magnesium, so it is a poor choice for correcting a deficiency.

Does magnesium L-threonate help sleep?

There is no dedicated trial of magnesium L-threonate for insomnia or anxiety, so the evidence is limited. Any benefit likely reflects fixing a magnesium shortfall, which cheaper forms do equally well.

Scientific references

Where to buy

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

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