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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*
  • *Corresponding author for this work
    • University of Canberra
    • Commonwealth Scientific and Industrial Research Organization
    • Australian National University Medical School
    • University of Notre Dame Australia
    • University of KwaZulu-Natal

    Research output: Contribution to journal › Review article › peer-review

    104   Link opens in a new tab Citations (SciVal)
    131 Downloads (Pure)

    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
    Early online date22 Dec 2019
    DOIs
    Publication statusPublished - Mar 2020

    Bibliographical note

    © Springer Nature B.V. 2019. The final publication is available at Springer via http://dx.doi.org/10.1007/s11130-019-00771-5

    Funding

    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.

    UN SDGs

    This output contributes to the following UN Sustainable Development Goals (SDGs)

    1. SDG 3 - Good Health and Well-being
      SDG 3 Good Health and Well-being

    Keywords

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

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