Magnesium Glycinate vs Magnesium L-Threonate

Mechanism

Magnesium is a cofactor for >600 enzymatic reactions including all ATP-dependent reactions (Mg-ATP is the true substrate), DNA/RNA polymerases, and ion channel regulation. Magnesium glycinate chelate provides highly bioavailable elemental magnesium bound to glycine. The glycine moiety itself is an inhibitory neurotransmitter (glycine receptors) and NMDA receptor co-agonist at the glycine binding site. The chelated form minimizes the osmotic laxative effect of ionic magnesium salts. Magnesium regulates NMDA receptor gating (voltage-dependent Mg2+ block), GABA-A receptor potentiation, HPA axis modulation, and parathyroid hormone secretion.

Standard Dosing

200-400mg elemental magnesium daily

Timing

Evening/bedtime (promotes relaxation and sleep quality). Can split AM/PM.

Cycle Duration

ongoing

Side Effects

• Drowsiness
• Mild GI discomfort
• Loose stools (less than other Mg forms)
• Hypotension at very high doses

Contraindications

• Severe renal insufficiency (impaired Mg excretion — risk of hypermagnesemia)
• Myasthenia gravis (Mg can worsen neuromuscular junction blockade)
• Heart block (Mg slows AV conduction)

Best Stacking Partners

Mechanism

Magnesium L-threonate (Magtein) was specifically developed by MIT researchers to cross the blood-brain barrier efficiently. L-threonate, a metabolite of vitamin C, acts as a carrier to increase brain magnesium concentration by ~15% (compared to negligible CNS penetration from other Mg forms). Elevated brain Mg2+ enhances NMDA receptor signaling fidelity, increases synaptic density in the hippocampus and prefrontal cortex, promotes BDNF expression, and enhances both short-term and long-term memory via potentiation of pre-synaptic release probability at hippocampal CA3-CA1 synapses.

Standard Dosing

1000-2000mg magnesium L-threonate daily (providing ~144mg elemental Mg per 2000mg)

Timing

Split dose: 1 capsule morning, 2 capsules before bed (or per product label). Evening dose supports sleep and overnight memory consolidation.

Cycle Duration

ongoing

Side Effects

• Drowsiness
• Headache (initial)
• Mild GI discomfort
• Cost (significantly more expensive than other Mg forms)

Contraindications

• Severe renal insufficiency
• Myasthenia gravis

Best Stacking Partners