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Magnesium L-Threonate vs Glycinate

This content is for informational purposes only and does not constitute medical advice. Consult your healthcare provider before starting any supplement. Full disclaimer

Magnesium L-threonate is best for cognitive support and memory because it crosses the blood-brain barrier.

Magnesium L-threonate is best for cognitive support and memory because it crosses the blood-brain barrier. Magnesium glycinate is better for sleep, relaxation, and affordable daily magnesium supplementation.

Head-to-Head Comparison

CriteriaMagnesium L-ThreonateGlycinateWinner
BioavailabilityModerate systemically — high in the brainHigh — ~80% systemic absorptionGlycinate
Clinical EvidenceEmerging — promising cognitive/memory dataModerate — well-established for sleep and anxietyGlycinate
GI TolerabilityExcellent — no reported GI issuesExcellent — chelated form minimizes GI effectsTie
Cost$0.80-1.50/day (patented Magtein)$0.20-0.50/day (widely available)Glycinate
Brain Penetration & Cognitive BenefitsUnique — proven to cross BBB, raises brain MgLimited — does not preferentially cross BBBMagnesium L-Threonate

Detailed Analysis

Bioavailability

Magnesium glycinate has superior overall systemic bioavailability due to its amino acid chelate. Threonate contains only ~8% elemental magnesium by weight (vs ~14% for glycinate), so it's not ideal for correcting whole-body magnesium deficiency — but it uniquely elevates brain magnesium levels.

Clinical Evidence

Glycinate has a longer track record with broader clinical use for sleep, anxiety, and muscle cramps. Threonate has a landmark 2010 Slutsky et al. animal study and a 2016 human trial showing cognitive improvements, but the overall clinical evidence base is still smaller and more recent.

GI Tolerability

Both forms are exceptionally well-tolerated. Neither has osmotic laxative effects like citrate or oxide. Both are chelated to organic molecules that prevent the loose stool commonly associated with ionic magnesium forms.

Cost

Threonate is significantly more expensive because Magtein is a patented compound developed at MIT. Glycinate is a generic chelate manufactured by dozens of supplement companies, keeping prices 2-4x lower per daily serving.

Brain Penetration & Cognitive Benefits

Magnesium L-threonate is the only magnesium form demonstrated to effectively cross the blood-brain barrier and raise cerebrospinal fluid magnesium levels. The Slutsky et al. study showed it enhanced synaptic density and improved learning and memory in both young and aged models. Glycinate provides systemic magnesium but does not preferentially target the brain.

Our Verdict

Choose threonate for cognitive and memory support; choose glycinate for sleep, relaxation, and cost-effective daily magnesium supplementation.

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Frequently Asked Questions

Can I take magnesium threonate and glycinate together?

Yes, many people stack both forms effectively. Take threonate in the morning or afternoon for cognitive benefits and glycinate in the evening for sleep and relaxation. Keep total elemental magnesium from all sources under 400mg/day from supplements to avoid exceeding the tolerable upper limit.

Which magnesium form is better for memory and brain health?

Magnesium L-threonate (Magtein) is the clear winner for brain health. It is the only form shown to cross the blood-brain barrier and increase cerebrospinal fluid magnesium levels. A 2010 study by Slutsky et al. in Neuron demonstrated it enhances synaptic plasticity and memory. Glycinate supports general relaxation but does not preferentially target the brain.

Is magnesium threonate worth the extra cost?

If your primary goal is cognitive support, memory, or brain health, the 2-4x price premium is justified by threonate's unique ability to cross the blood-brain barrier. However, if you need magnesium for sleep, muscle cramps, or general deficiency correction, glycinate delivers more elemental magnesium per dollar and is the better value.

Why does magnesium threonate have so little elemental magnesium per capsule?

Magnesium L-threonate contains only about 8% elemental magnesium by weight because the threonate molecule is relatively large. A typical 2,000mg daily dose provides only about 144mg of elemental magnesium. This is by design — the value of threonate is not in the magnesium quantity but in its unique ability to transport magnesium across the blood-brain barrier.

References

  1. Slutsky I, Abumaria N, Wu LJ, Huang C, Zhang L, Li B, Zhao X, Govindarajan A, Zhao MG, Zhuo M, Tonegawa S, Liu G (2010). Enhancement of learning and memory by elevating brain magnesium. Neuron. DOI PubMed
  2. Liu G, Weinger JG, Lu ZL, Xue F, Sadeghpour S (2016). Efficacy and Safety of MMFS-01, a Synapse Density Enhancer, for Treating Cognitive Impairment in Older Adults: A Randomized, Double-Blind, Placebo-Controlled Trial. Journal of Alzheimer's Disease. DOI PubMed