howtosupplement
Mood/Sleep/Cognition

L-Theanine

Tea amino acid that promotes calm focus and may improve stress, sleep, and attention in adults under mental load.

L-Theanine

L-Theanine

64
score
B
evidence
Safe
risk

Proven Benefits

01Reduces stress and anxiety
02Improves sleep quality
03May improve attention with caffeine
04May reduce mental fatigue
05May reduce caffeine jitters

Chemical Forms

Recommended
  • L-Theanine
  • L-Theanine (fermentation-derived)
  • L-Theanine (tea-derived)
Avoid
  • DL-Theanine or D-Theanine (less studied than pure L-isomer)
  • Green tea extract used as a theanine substitute (variable caffeine and theanine content)
Expert Note

Human studies primarily use pure L-theanine, the naturally occurring isomer in tea. Fermentation-derived and tea-derived L-theanine are both reasonable if identity is verified, while racemic forms are less studied and tea extracts can add unpredictable caffeine.

Protocol

Amount
100-200 mg
Frequency
Once or twice daily
When
30-60 minutes before a stressful task, with caffeine, or before bed; with or without food.

Condition-Based Dosing

Acute stress or tension
100-200 mg 30-60 minutes before the stressful event
With caffeine for focus
100-200 mg L-theanine with 50-100 mg caffeine
Stress-related sleep quality issues
200 mg 30-60 minutes before bed

Safety & Limits

Upper Safe Limit
No official UL established; 400 mg/day is a commonly studied adult dose without major safety concerns.
Cycling
Safe for continuous use

Contraindications

Pregnancy or breastfeeding — insufficient supplemental safety data
Low blood pressure or antihypertensive medication — may further lower blood pressure in some people
Sedatives or other calming agents — may increase drowsiness in sensitive users

Synergies

Caffeine

L-theanine can smooth stimulant-related tension while preserving or improving alertness and attention compared with caffeine alone.

Avoid Combining With

  • ✕Very high caffeine intake (can overwhelm the calming effect)
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