L-Theanine
nootropics
Amino acid found in green tea. Promotes calm focus without drowsiness. Synergistic with caffeine for clean, jitter-free energy.
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Benefits
Dosage
Typical Dose
100-200mg daily
Upper Limit
400mg daily
Timing
With caffeine for focus, or evening for relaxation
Forms & Bioavailability
L-Theanine (Suntheanine)
High — patented, pure L-isomer
Generic L-Theanine
Good — may contain D-theanine (less active)
Side Effects
Interactions
Research Summary
Well-studied amino acid. Multiple trials show improved attention and reduced anxiety. The L-theanine + caffeine combination is one of the most replicated nootropic findings.
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The Bottom Line on L-Theanine
L-Theanine is well-researched with strong evidence supporting its primary benefits.It is most commonly used for calm focus without sedation and reduces caffeine jitters when combined. As with any supplement, individual results vary. Start with the lower end of the dosage range and assess for 4-8 weeks before adjusting.
About Our Research
This profile is compiled from peer-reviewed research published on PubMed, the NIH Office of Dietary Supplements, and established nutritional science databases. Dosages reflect clinically-studied amounts from human trials where available. We update profiles as new research emerges. This is not medical advice — consult a healthcare professional before supplementing.
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Goal Guides for L-Theanine
See how L-Theanine can help with specific health goals: