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

Jackson L. Williams, Julian M. Everett, Nathan M. D’Cunha, Domenico Sergi, Ekavi N. Georgousopoulou, Richard J. Keegan, Andrew J. McKune, Duane D. Mellor, Nicola Anstice, Nenad Naumovski

Research output: Contribution to journalReview article

2 Citations (Scopus)

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.

Original languageEnglish
Pages (from-to)12-23
Number of pages12
JournalPLANT FOODS FOR HUMAN NUTRITION
Volume75
Issue number1
Early online date22 Nov 2019
DOIs
Publication statusPublished - Mar 2020
Externally publishedYes

Keywords

  • Anxiety
  • Green tea
  • Human trials
  • L-theanine
  • Mental health
  • Stress response

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    Williams, J. L., Everett, J. M., D’Cunha, N. M., Sergi, D., Georgousopoulou, E. N., Keegan, R. J., McKune, A. J., Mellor, D. D., Anstice, N., & Naumovski, N. (2020). The Effects of Green Tea Amino Acid L-Theanine Consumption on the Ability to Manage Stress and Anxiety Levels: a Systematic Review. PLANT FOODS FOR HUMAN NUTRITION, 75(1), 12-23. https://doi.org/10.1007/s11130-019-00771-5