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L-Theanine
Tea-derived amino acid that boosts alpha brain waves for calm, focused alertness — synergizes with caffeine to reduce jitteriness.
What the evidence says
L-Theanine appears to help in 4 of 5 studies with measurable effects — the evidence leans clearly favourable.
Most evidence is from high-quality meta-analyses and randomised trials published 2007–2026 with a typical study size of 29 participants.
Based on 35 studies · 4 meta-analyses · 22 RCTs · 2,349 total participants
Confidence
HighWhat the studies found
By outcome
See full supplement plans that include L-Theanine.
L-Theanine has an evidence score of 9/10 — very strong evidence based on 35 indexed studies, including 4 meta-analyses. Tea-derived amino acid that boosts alpha brain waves for calm, focused alertness — synergizes with caffeine to reduce jitteriness.
The commonly studied dose of L-Theanine is 100-200mg. Research points to an estimated optimal dose around 200mg, with a minimum effective dose near 100mg. Individual response varies — start low and adjust.
Timing is flexible for L-Theanine — consistent daily use matters more than the time of day. L-theanine is a non-proteinogenic amino acid found primarily in Camellia sinensis (tea).
Last reviewed May 2026 · evidence from 39 studies · how we score
This information is for educational purposes only. It is not a substitute for professional medical advice. Always consult a qualified healthcare provider before starting, stopping, or changing any supplement or medication.
L-Theanine is a unique amino acid found primarily in tea leaves. It crosses the blood-brain barrier and promotes alpha brain wave activity, creating a state of calm alertness. It's particularly effective for reducing anxiety and jitteriness from caffeine while maintaining focus.
Increases alpha wave activity associated with relaxed alertness
Modulates excitatory and inhibitory neurotransmitters
Supports feel-good neurotransmitter levels
How L-Theanine works — from molecular targets to health outcomes. Click an edge to see supporting research.This visualization is in beta — pathways are being refined and expanded.
100-200mg
Can be taken without food
| Form | Type |
|---|---|
| 💊Suntheanine® capsules or powder | Recommended |
| 💊Generic L-theanine | Alternative |
| 🍵Green tea (lower dose) | Alternative |
Suntheanine is the most studied form. A cup of green tea contains ~20-30mg L-theanine. Capsules provide consistent dosing.
Minimum: 1 weeks
Optimal: 2 weeks
Cycling: Not required
Note: Works within 30-60 minutes. Can be taken multiple times daily. Popular combination: 100mg L-theanine with each cup of coffee.
You can get l-theanine from these foods and drinks. Doses are typical per-serving estimates — actual content varies by brand, brew, cooking, etc.
25 mg per cup
1 tsp (~2 g) matcha powder whisked in 8 oz water. Ceremonial-grade tends higher; culinary lower.
8 mg per cup
8 oz brewed, 2–3 min steep. Gyokuro / shade-grown teas are higher in L-theanine.
Meta-analysis (n=897) and multiple RCTs support sleep benefits. Studies often used L-theanine in combination with other compounds, limiting pure L-theanine effect attribution. Effects include reduced sleep onset latency and improved subjective sleep quality.
Relaxed but alert mental state
Smooths out caffeine's stimulating effects
Reduced mental tension and racing thoughts
Effects are gentle; may be subtle for some
Limited data; green tea is generally considered safe but supplements should be discussed with doctor
Some evidence for ADHD; consult pediatrician for dosing
May have additive blood pressure lowering effects
May modify stimulant effects (often desirable)
Tip: Reduce dose
Tip: More common at higher doses or in sensitive individuals
Classic nootropic stack for focus without jitters
Caffeine's alertness with L-theanine's calm; reduced side effects
Both reduce anxiety through different mechanisms
Comprehensive anxiety and stress support
Magnesium supports GABA while L-theanine promotes alpha waves
Enhanced relaxation and sleep quality
L-Theanine promotes alpha waves, apigenin binds GABA
Calming effect from multiple pathways
Both promote calm through different mechanisms
Enhanced relaxation without sedation
Both promote relaxation through different mechanisms
Enhanced pre-sleep relaxation and sleep quality
Naturally occurring combination in tea
Focused calm without jitters
Different mechanisms for anxiety reduction
Comprehensive anxiety support
Both promote relaxation through different mechanisms
Enhanced calm without excessive sedation
Both promote calm through different mechanisms
Gentle anxiety relief without drowsiness
Both promote relaxation through different mechanisms
Enhanced calm without sedation
L-Theanine calms the mind without sedation
Reduced sleep anxiety combined with circadian regulation
L-theanine calms while rhodiola energizes
Alert calmness with stress resilience
L-Theanine is generally well-tolerated and considered safe for most healthy adults at recommended doses. The most commonly reported side effects are headache, drowsiness. Use caution if any of these apply to you: None known at recommended doses.
5-HTP
Likely helpsDirect serotonin precursor that may support mood, sleep, and appetite control, but requires caution with certain medications.
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