L-Theanine
Commonly used for
SleepFocusAnxiety
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The cheapest product is usually low quality, but more expensive doesn’t always mean better.
What is it? / Overview
L-theanine is an amino acid found naturally in tea that promotes relaxation without causing drowsiness. When paired with caffeine it can improve attention while reducing the jitteriness caffeine sometimes causes.
How is it used? / Administration
Form: Suntheanine or pure L-theanine
Typical dose studied: 100–200 mg/day; 100–200 mg paired with caffeine for focus
Timing: Morning for focus; evening for relaxation
Excellent option alongside moderate-dose caffeine. Very well tolerated with a strong safety profile.
How well does it work? / Evidence
~ Moderate evidence
Who should avoid it?
Avoid with: Hypotension / Low blood pressure
Interacts with: Antihypertensives; Sedatives
Already taking it? Reduce caffeine if excessive stimulation persists.
Research & references
Haskell CF et al. (2008). L-theanine, caffeine, and cognition. Biological Psychology. Hidese S et al. (2019). L-theanine and stress-related symptoms RCT. Nutrients. Williams JL et al. (2020). Theanine as functional food ingredient. Plant Foods for Human Nutrition.
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