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


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.

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Divisions: College of Health & Life Sciences > Aston Medical School
Funding Information: J Williams is supported by an Australian Government Research Training Program scholarship. N.M. D’Cunha is supported by a Dementia Australia Research Foundation PhD scholarship. All other authors declare no funding sources.
Additional Information: © Springer Nature B.V. 2019. The final publication is available at Springer via
Uncontrolled Keywords: Anxiety,Green tea,Human trials,L-theanine,Mental health,Stress response,Food Science,Chemistry (miscellaneous)
Publication ISSN: 1573-9104
Last Modified: 13 May 2024 17:06
Date Deposited: 08 Jan 2020 11:32
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Related URLs: http://www.scop ... tnerID=8YFLogxK (Scopus URL)
https://link.sp ... 130-019-00771-5 (Publisher URL)
PURE Output Type: Review article
Published Date: 2020-03
Published Online Date: 2019-12-22
Accepted Date: 2019-11-01
Authors: Williams, Jackson L.
Everett, Julian M.
D’Cunha, Nathan M.
Sergi, Domenico
Georgousopoulou, Ekavi N.
Keegan, Richard J.
McKune, Andrew J.
Mellor, Duane D. (ORCID Profile 0000-0002-1369-3868)
Anstice, Nicola
Naumovski, Nenad



Version: Accepted Version

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