Stimulants & Focus
L-Theanine
Paired with caffeine, L-theanine smooths stimulant jitteriness and enhances sustained focus. One of the most reliable cognitive stacks.
Effective Dose
100–200mg / dose
per clinical evidence
Evidence Level
Moderate
Stimulants & Focus
Mechanism
GABA modulation, alpha-wave activity
primary action
Best For
Focus
Anxiety reduction, Caffeine synergy
This profile is for informational purposes only and does not constitute medical advice. Consult a qualified healthcare professional before starting any supplementation, especially if you have pre-existing conditions or take medications.
What Is L-Theanine?
L-theanine is a non-protein amino acid found almost exclusively in tea leaves (Camellia sinensis). It crosses the blood-brain barrier and promotes a state of relaxed alertness without sedation — which is why tea drinking feels different to coffee despite similar caffeine content. Its combination with caffeine is one of the best-studied cognitive stacks.
How It Works: The Science
Theanine modulates GABA, glycine, dopamine, and serotonin neurotransmission, increasing alpha brainwave activity (associated with relaxed focus). It blunts the norepinephrine spike caused by caffeine, reducing anxiety and cardiovascular side effects while preserving cognitive benefits. It may also modulate NMDA receptor activity.
Primary Mechanism
GABA modulation, alpha-wave activity
Evidence-Based Benefits
Dosage Guide
Effective Dose
100–200mg / dose
100–200mg per dose, often at a 2:1 ratio with caffeine (e.g. 200mg theanine + 100mg caffeine). Standalone use at 200–400mg/day may support sleep and stress reduction. Onset within 30–60 minutes.
Safety Profile & Side Effects
Extremely well tolerated with no known serious adverse effects at recommended doses. No dependency or withdrawal. Generally recognised as safe (GRAS) in the US.
Who Should (and Shouldn't) Take It
Anyone using caffeine who experiences jitteriness, anxiety, or a post-caffeine crash. Also useful as a standalone supplement for focus during stressful cognitive work. Not a stimulant — does not replace caffeine.
Frequently Asked Questions
Related Ingredients
Medical Disclaimer
Ingredient profiles are for informational purposes only and do not constitute medical advice. Consult a qualified healthcare professional before starting any supplementation, especially if you have pre-existing conditions or take medications. Full disclaimer →