Quick Comparison
| Magnesium L-Threonate | Polygala Tenuifolia | |
|---|---|---|
| Half-Life | 2-3 hours (threonate carrier), but brain magnesium levels increase cumulatively | 3-6 hours (tenuigenin and polygalasaponins) |
| Typical Dosage | Standard: 1500-2000 mg Magnesium L-Threonate daily (providing 144 mg elemental magnesium). Often split into a daytime dose and a pre-bed dose. The Magtein brand uses 2000 mg daily (667 mg three times). | Standard: 100-300 mg extract daily (standardized to 3,6'-disinapoyl sucrose or polygalasaponins). Can be taken morning or evening. Some users take it before bed for dream enhancement. Effects noticeable within hours of first dose. |
| Administration | Oral (capsules, powder). The L-threonate form is specifically chosen for brain penetration. | Oral (capsules, powder, tincture). Extract preferred over raw root for potency and reduced GI irritation. |
| Research Papers | 10 papers | 10 papers |
| Categories |
Mechanism of Action
Magnesium L-Threonate
The L-threonate carrier forms stable complexes with magnesium and transports it across the blood-brain barrier via specific transporters more effectively than inorganic magnesium salts or other chelated forms. Once in the brain, magnesium acts as a voltage-dependent blocker of the NMDA receptor channel at the physiological magnesium binding site within the ion pore, preventing excessive calcium influx and glutamate-mediated excitotoxicity. Magnesium also serves as a cofactor for over 300 enzymes including those involved in neurotransmitter synthesis (tyrosine hydroxylase, glutamic acid decarboxylase), ATP production (creatine kinase, pyruvate kinase), and DNA/RNA polymerase. Elevated brain magnesium enhances synaptic density and plasticity in the hippocampus and prefrontal cortex, likely through CREB-mediated gene expression and increased density of postsynaptic AMPA receptors.
Polygala Tenuifolia
The saponins (tenuigenin, polygalasaponins, onjisaponins) and oligosaccharide esters (3,6'-disinapoyl sucrose, tenuifolisides) have multiple neurological actions. They inhibit acetylcholinesterase (AChE) at the catalytic site, increasing synaptic acetylcholine and enhancing muscarinic M1/M4 and nicotinic receptor signaling. They promote BDNF and NGF expression via CREB and ERK/MAPK pathways, supporting neuroplasticity and neurogenesis in the hippocampus and subventricular zone. They modulate NMDA receptor function (possibly as positive allosteric modulators at the glycine site) and enhance long-term potentiation (LTP) via CaMKII and PKC. The anti-depressant effects involve monoaminergic modulation — increasing dopamine and norepinephrine via MAO inhibition or reuptake modulation — and HPA axis regulation (reducing CRH and cortisol). Tenuigenin may also activate TrkB receptors directly.
Risks & Safety
Magnesium L-Threonate
Common
Drowsiness (often desired for sleep), mild headache initially, gastrointestinal discomfort.
Serious
None documented at standard doses. Magnesium toxicity is not a concern with oral supplementation in people with normal kidney function.
Rare
Diarrhea (less common than with other magnesium forms).
Polygala Tenuifolia
Common
Nausea, gastrointestinal irritation (take with food).
Serious
Limited long-term safety data in Western research.
Rare
Throat irritation, excessive salivation.
Full Profiles
Magnesium L-Threonate →
A form of magnesium specifically designed to cross the blood-brain barrier and increase brain magnesium levels. Developed at MIT, it is the only magnesium form clinically shown to raise CSF magnesium concentrations. Brain magnesium is critical for synaptic plasticity, and deficiency (common in modern diets) impairs learning, memory, and sleep quality. Sold under the brand name Magtein.
Polygala Tenuifolia →
Known as Yuan Zhi in Traditional Chinese Medicine, Polygala tenuifolia has been used for thousands of years as a 'will-strengthening' and memory-enhancing herb. Modern research shows it enhances BDNF expression, inhibits acetylcholinesterase, and promotes neurogenesis. Users commonly report improved verbal fluency, dream vividness, and motivation. One of the more noticeable adaptogens with acute effects.