L-theanine
Glutamate-analog amino acid from Camellia sinensis (tea). Crosses BBB; modulates GABA, dopamine, serotonin, and alpha-wave generation.
γ-glutamylethylamide. Naturally present in green and black tea (5-25 mg per cup). At supplemental doses (100-200 mg) it produces a shallow but reproducible alpha-wave EEG signature consistent with relaxed-but-alert state. Reliably reduces caffeine jitter without blunting the alertness — the classic L-theanine + caffeine 2:1 stack is the most consistent nootropic effect documented in the broader literature.
Distilled themes from named communities — Reddit threads, forums, creator commentary. Not direct quotes; not clinical evidence. Useful for calibrating expectations against what real self-experimenters report.
L-theanine + caffeine 2:1 is the 'first nootropic stack' across cohorts. Cohort consensus: undeniable jitter-reduction effect; standalone benefit smaller than the combo.
Very wide safety margin. Mild sedation at >400 mg in some users. Not a sleep aid by itself; combines with magnesium glycinate or apigenin for that purpose. Generic powder is fine — branded forms (Suntheanine = Taiyo trademark, single-isomer) are slightly cleaner but the price-per-mg gap is real.
External links to PubMed searches, ClinicalTrials.gov, and FDA materials. We do not host papers — we point at canonical sources.
- PubMedENRCTIndustry-fundedVerified 3d agoOwen GN et al. — L-theanine + caffeine cognitive performance (Nutr Neurosci 2008)
- PubMedENRCTIndustry-fundedVerified 3d agoNobre AC et al. — L-theanine alpha-wave EEG study (Asia Pac J Clin Nutr 2008)
- Clinical trialENRCTFunding undisclosedVerified 3d agoClinicalTrials.gov — L-theanine registered trials
GRAS-classified in US. Sold OTC. EU novel-food approved 2008.