L-theanine

free amino acid, from tea or synthesis

The amino acid that makes tea calming without sedation. Small trials support a take-the-edge-off effect, especially paired with caffeine; nothing here is large.

last reviewed 2026-08-30

by draft — unverified

GRADE

CLAIM

SPECIES

EFFECT

STUDIES

acute stress & anxiety reduction — grade C, small effect (human-rct)

Hidese et al. (2019)

species humandesign RCT, double-blind crossovern 30duration 4 weeksdose 200 mg/dayfunding industryoutcome stress and sleep questionnaires

Lower stress scores and better sleep ratings — small sample, subjective endpoints, manufacturer involvement.

attention, combined with caffeine — grade C, small effect (human-rct)

Grade timeline

No grade movement since first review.

Dosing & safety

TYPICAL SUPPLEMENT DOSE100–400 mg/day

DOSES USED IN STUDIES200–400 mg/day

UPPER LIMITnone established

COST SNAPSHOT

No product records for this compound yet.

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