Quick Comparison
| B-Complex | Magnesium L-Threonate | |
|---|---|---|
| Half-Life | Water-soluble; excreted daily (except B12 which is stored) | 2-3 hours (threonate carrier), but brain magnesium levels increase cumulatively |
| Typical Dosage | Standard: A quality B-complex providing 25-100 mg of B1, B2, B3, B5, B6, plus 400-800 mcg folate (as methylfolate) and 500-1000 mcg B12 (as methylcobalamin). Methylated forms preferred for B9 and B12 (folate → methylfolate, B12 → methylcobalamin). Take in the morning — B vitamins can be mildly energizing. | 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). |
| Administration | Oral (capsules, tablets, sublingual). Methylated forms preferred for B9 and B12. Take with breakfast. | Oral (capsules, powder). The L-threonate form is specifically chosen for brain penetration. |
| Research Papers | 10 papers | 10 papers |
| Categories |
Mechanism of Action
B-Complex
Each B vitamin serves specific neurological functions: B1 (thiamine) — cofactor for transketolase (pentose phosphate pathway), pyruvate dehydrogenase, and alpha-ketoglutarate dehydrogenase; essential for glucose metabolism and ATP production in neurons. B2 (riboflavin) — precursor to FAD/FMN, cofactors for Complex I and II of the electron transport chain, and glutathione reductase. B3 (niacin/niacinamide) — precursor to NAD+/NADPH via the salvage pathway; NAD+ is substrate for sirtuins, PARP, and 400+ dehydrogenases. B5 (pantothenic acid) — component of coenzyme A, required for acetylcholine synthesis via choline acetyltransferase and for fatty acid oxidation. B6 (pyridoxine) — cofactor for AADC (5-HTP to serotonin, L-DOPA to dopamine), GABA synthesis (GAD), and homocysteine metabolism. B9 (folate) — tetrahydrofolate donates methyl groups for dTMP and purine synthesis, and for homocysteine remethylation. B12 (cobalamin) — cofactor for methionine synthase (myelin maintenance) and methylmalonyl-CoA mutase.
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.
Risks & Safety
B-Complex
Common
Bright yellow urine (harmless — riboflavin excretion), mild nausea.
Serious
Very safe at standard doses. B6 can cause peripheral neuropathy at >200 mg daily for extended periods.
Rare
Flushing from niacin (B3) if non-flush form is not used.
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).
Full Profiles
B-Complex →
The B vitamins (B1, B2, B3, B5, B6, B9, B12) are essential coenzymes in brain energy metabolism, neurotransmitter synthesis, and methylation reactions. Deficiency in any B vitamin impairs cognitive function. B12 and folate deficiency specifically cause irreversible neurological damage if untreated. A high-quality B-complex is foundational for any nootropic regimen, particularly for vegetarians, older adults, and those under chronic stress.
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.