Focus / nootropic evidence brief
L-theanine is an amino acid found in tea. It is usually used for calm focus, stress smoothing, and as a pairing ingredient with caffeine.
May support attention and calmer alertness when paired with caffeine; standalone effects are less dependable.
Systematic review evidence is strongest for caffeine-plus-theanine attention rather than theanine alone.
Often used alongside caffeine; the practical question is whether it improves focus without muting caffeine's useful arousal.
Best understood as focus or stimulant-tolerability support. Standalone theanine claims need clearer independent effects.
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