The Effects of Green Tea Amino Acid L-Theanine Consumption on the Ability to Manage Stress and Anxiety Levels: a Systematic Review

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#amino-acids #anxiety #glutamates #humans #randomized-controlled-trials-as-topic

The Effects of Green Tea Amino Acid L-Theanine Consumption on the Ability to Manage Stress and Anxiety Levels: a Systematic Review

Williams et al., 2020 | Plant Foods Hum Nutr | Systematic Review

Citation

Williams Jackson L, Everett Julian M, ... Naumovski Nenad. The Effects of Green Tea Amino Acid L-Theanine Consumption on the Ability to Manage Stress and Anxiety Levels: a Systematic Review. Plant Foods Hum Nutr. 2020-Mar;75(1):12-23. doi:10.1007/s11130-019-00771-5

Abstract

The green tea amino acid, L-theanine (L-THE) is associated with several health benefits, including improvements in mood, cognition and a reduction of stress and anxiety-like symptoms. This systematic review evaluated the effect of pure L-THE intake, in the form of orally administered nutritional supplements, on stress responses and anxiety levels in human randomised controlled trials. Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) checklist, 9 peer-reviewed journal articles were identified where L-THE as a supplement was compared to a control. Our findings suggest that supplementation of 200-400 mg/day of L-THE may assist in the reduction of stress and anxiety in people exposed to stressful conditions. Despite this finding, longer-term and larger cohort clinical studies, including those where L-THE is incorporated into the diet regularly, are needed to clinically justify the use of L-THE as a therapeutic agent to reduce stress and anxiety in people exposed to stressful conditions.

Key Findings

Despite this finding, longer-term and larger cohort clinical studies, including those where L-THE is incorporated into the diet regularly, are needed to clinically justify the use of L-THE as a therapeutic agent to reduce stress and anxiety in people exposed to stressful conditions.

Outcomes Measured

  • anxiety

Population

Field Value
Population See abstract
Sample Size See abstract
Age Range See abstract
Condition anxiety

MeSH Terms

  • Amino Acids
  • Anxiety
  • Glutamates
  • Humans
  • Randomized Controlled Trials as Topic
  • Tea

Evidence Classification

  • Level: Systematic Review
  • Publication Types: Journal Article, Systematic Review
  • Vertical: l-theanine-anxiety

Provenance

Source extracted via PubMed E-utilities API on 2026-04-09