L-Theanine
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L-Theanine. Calm focus — alpha-wave amino acid from green tea that takes the edge off caffeine.
How it works. Structurally similar to glutamate; binds AMPA, NMDA, and kainate receptors as a weak agonist/antagonist. Increases GABA, dopamine, serotonin; raises alpha-wave EEG activity.
What the research supports. 3 graded claims. Strongest: Improves focus and attention when combined with caffeine (strong).
How much to take. Typical dose: 100–200 mg. 30–40 min before a focus task or with caffeine.
Side effects and interactions. 2 medication interactions listed. No serious side effects listed at normal doses.
Stacking. Pairs well with Caffeine (2:1 theanine:caffeine), Magnesium glycinate.
Common forms. Available as L-theanine (active enantiomer), Suntheanine (patented, ≥99% L-isomer).
Key studies. 10 studies cited. The strongest are listed with links to PubMed.
Community. Experiences from people who have tried L-Theanine. Anecdotes are not medical advice.
L-Theanine. Calm focus — alpha-wave amino acid from green tea that takes the edge off caffeine.
What it is
A non-proteinogenic amino acid found almost exclusively in tea (Camellia sinensis). Crosses the BBB and increases alpha-wave activity within 30–40 min.
Food sources
Goals
How it works
Structurally similar to glutamate; binds AMPA, NMDA, and kainate receptors as a weak agonist/antagonist. Increases GABA, dopamine, serotonin; raises alpha-wave EEG activity.
Pathways
- Alpha-wave induction
- Glutamate receptor modulation
Effects
- ↑Alpha-wave EEG activity increases
- +Calm focus supports
- ↓Caffeine-induced jitters decreases
- ↓Stress reactivity decreases
What the research supports
Strong: consistent results across large trials or meta-analyses. Moderate: several trials, mostly positive. Limited: small or mixed studies. Preclinical: animal or cell research only.
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Side effects & interactions
Common side effects
- None at typical doses
Medication interactions
Additive BP-lowering possible.
Synergistic — usually beneficial.
Check any supplement–medication combination with your pharmacist before starting.
Combines with
Pairs well
- Caffeine (2:1 theanine:caffeine)Classic nootropic stack for clean focus.
- Magnesium glycinateSynergistic for sleep & stress.
Common forms
- L-theanine (active enantiomer)
- Suntheanine (patented, ≥99% L-isomer)
Key studies
10 studies cited in total.
Opens current human and preclinical literature matching L-Theanine and "Improves focus and attention when combined with caffeine". Filter by RCT, meta-analysis, or year on the results page.
Opens current human and preclinical literature matching L-Theanine and "Reduces acute stress and anxiety". Filter by RCT, meta-analysis, or year on the results page.
Opens current human and preclinical literature matching L-Theanine and "Improves sleep quality". Filter by RCT, meta-analysis, or year on the results page.
Discussion
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