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Clinical ResearchResearch compoundModerate evidence

L‑Threonic Acid

Vitamin C metabolite four-carbon sugar acid; as a nootropic it is the threonate carrier in magnesium L-threonate.

NootropicMemoryMemorynoo.affects.memoryNMDAnoo.affects.neuroprotection

Pharmacology

ClassMemory
Primary targetBrain magnesium delivery and NMDA receptor modulation (as threonate carrier)
Targets3 receptor targets
Half-lifeNo well-documented pharmacokinetic half-life for L-threonic acid in humans
OnsetWith magnesium L-threonate, cognitive effects typically appear after weeks of daily dosing
EvidenceModerate evidence
Affected systemsnoo.affects.memoryNMDAnoo.affects.neuroprotection

Contents

WHAT IS L-THREONIC ACID?

Detailed overview

L-Threonic acid is a four-carbon sugar acid and a natural metabolite of ascorbic acid (vitamin C). On its own it is barely studied, and its cognitive relevance comes almost entirely from the magnesium L-threonate (Magtein) salt, in which the threonate anion acts as a carrier that helps magnesium reach the brain. With elevated brain magnesium, animal studies showed enhanced learning and memory alongside greater synaptic density and altered hippocampal NMDA-receptor signaling, and a randomized, placebo-controlled human trial in older adults reported improvements on memory tests. Threonic acid is handled as a dietary-supplement ingredient rather than an approved pharmaceutical.

Mechanism

Threonate carrier: raises brain Mg2+, NMDA modulation

Evidence

Moderate (human RCT for the Mg salt)

Legal status

Dietary-supplement ingredient

Receptor profile

  • Brain magnesium levels (threonate carrier)Strong
  • NMDA receptors (Mg2+-dependent modulation)Moderate
  • Synaptic density / hippocampal plasticityModerate

Safety

Side effects, stop signs, contraindications

Side effects · 4

  • On its own (without magnesium) it is barely studied; most data come from the magnesium L-threonate salt
  • With magnesium L-threonate, headache, drowsiness and mild dizziness can occur, mainly during the ramp-up phase
  • Mild gastrointestinal upset or loose stools at higher magnesium doses
  • Vivid dreams or lighter sleep in some people when taken in the evening

Contraindications · 4

  • Severe kidney disease: magnesium can accumulate, medical supervision required
  • Bradycardia or cardiac conduction disorders: magnesium can affect conduction
  • Magnesium can impair absorption of some antibiotics (tetracyclines, quinolones) and bisphosphonates: separate the dosing in time
  • Pregnancy and breastfeeding: insufficient data on the threonate form, consult a doctor

Related Nootropics

Same therapeutic category

Studies

Related research and clinical findings

FAQ

FAQ

Vitamin C metabolite four-carbon sugar acid; as a nootropic it is the threonate carrier in magnesium L-threonate.

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Structure & chemistry

TypeNootropic
FormulaC4H8O5
UpdatedJuly 10, 2026
MolekulaX Editorial Team·Source-verified · PubMed · FDA · EMA
Updated: July 10, 2026

The information here is strictly for educational and scientific purposes. It does not replace medical advice or clinical consultation, and it does not encourage illegal substance or pharmaceutical use. Data is sourced. When in doubt, consult your doctor.