Magnesium L-Threonate vs Potassium (Citrate)

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

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Mechanism

Potassium is the principal intracellular cation, maintaining resting membrane potential (-70 to -90mV) via the Na+/K+-ATPase pump (3 Na+ out, 2 K+ in per ATP). It is essential for: cardiac rhythmicity (phase 3 repolarization of cardiac action potential), skeletal muscle contraction, nerve impulse transmission, acid-base balance (exchanged for H+ in renal tubules), blood pressure regulation (promotes natriuresis via renal sodium excretion), and insulin secretion. Citrate form provides alkalinizing anion that inhibits calcium oxalate and uric acid kidney stone formation.

Standard Dosing

99-200mg per capsule (regulatory limit in US); dietary target 3500-4700mg/day total

Timing

With meals, divided throughout the day. Slow-release forms preferred for higher doses.

Cycle Duration

ongoing

Side Effects

• GI irritation/ulceration (non-microencapsulated forms)
• Nausea
• Diarrhea
• Hyperkalemia (dangerous — cardiac arrhythmias)

Contraindications

• Hyperkalemia
• Renal insufficiency (impaired K+ excretion)
• Addison's disease (aldosterone deficiency)
• Concurrent ACE inhibitor/ARB + potassium-sparing diuretic

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