L-Theanine
A green-tea amino acid studied for stress and relaxation.
Supplements
Research records
Historical source snapshot. Not freshly verified, not a recommendation. Study findings, community accounts and app defaults are not interchangeable.
Publication suitability · 2026-10-15: Historical reference only; not a clinical verification. Clinical, regulatory, efficacy, safety and dose claims are not independently established by this review.
L-Theanine
A green-tea amino acid studied for stress and relaxation.
Evidence category: Systematic review. This describes the source category, not approval or certainty.
Regulatory statement in source: Not separately recorded; do not infer approval from the evidence category.
L-theanine is an amino acid found naturally in green tea leaves that crosses the blood-brain barrier and has been studied for effects on relaxation, attention and the stress response. A systematic review of randomized controlled trials examined its effect on stress and anxiety measures in adults exposed to stressful conditions.
Benefits reported in the imported source
- Reduces self-reported stress in adults under stressful conditions in most trials
- Well tolerated, with a low rate of reported side effects
- Effects appear rapidly, within a single dose in some trials
Risks and limits
- Anxiety-specific effects are inconsistent across trials
- Most trials are short-term and small, limiting confidence for long-term use
- Evidence is not yet sufficient to establish a role as a stand-alone therapy for anxiety disorders
Source bottom line: Randomized trial evidence supports a modest, short-term stress-reduction effect, but larger and longer trials are needed to confirm a role in anxiety management.
Uncertainty: Reference information only. Not medical advice.
Study protocols — reports, not instructions
Adults exposed to acute or chronic stressful conditions across nine randomized controlled trials
- Reported regimen
- 200 to 400 mg per day of L-theanine as an oral supplement, with trial durations ranging from a single dose to several weeks
- Duration
- Single dose to several weeks across the nine trials reviewed
- Reported outcome
- Reduced self-reported stress and anxiety measures compared with control in most trials reviewed, though anxiety-specific effects were inconsistent
- Source
- The Effects of Green Tea Amino Acid L-Theanine Consumption on the Ability to Manage Stress and Anxiety Levels: a Systematic Review - PubMed
Claim provenance
evidence.json#/catalog:supplement:l-theanine/protocols/0
Community and practice descriptions
Accounts of a practice are not evidence of safety or effectiveness. Words such as “standard”, “safe” or “recommended” describe the source account, not verified consensus or this wiki’s advice. Commercial and self-published citations are retained for traceability, not vendor endorsement or independent clinical corroboration.
Historical research outcome: no-verified-description · 2026-10-06
No suitable community description was independently verified in these checks. The entry remains empty; this does not establish that no practice exists elsewhere.
- https://www.mskcc.org/cancer-care/integrative-medicine/herbs/l-theanine: no-practice-description — The inspected reference discusses food sources, purported uses, research and clinical cautions. No trial or expert suggestion was recast as community practice.
Pharmacokinetic context
No half-life recorded in this source snapshot. No value has been inferred.
Source references
Snapshot provenance
Source ID: catalog:supplement:l-theanine. Commit: adc7684614f9439b41d91a3312b62e7982c7e20e. Review state: historical-not-reverified. Authored links are retained separately from the canonical evidence links in the public data. App templates/defaults and rejected drafts are archived, not deployed.
Related entries and components
None listed.