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Plant Foods Hum Nutr. 2019 Nov 22. doi: 10.1007/s11130-019-00771-5. [Epub ahead of print]

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

Author information

1
Faculty of Health, University of Canberra, Canberra, ACT, 2601, Australia.
2
Collaborative Research in Bioactives and Biomarkers (CRIBB) Group, University of Canberra, Bruce, ACT, 2601, Australia.
3
Nutrition & Health Substantiation Group, Nutrition and Health Program, Health and Biosecurity, Commonwealth Scientific and Industrial Research Organisation (CSIRO), Adelaide, SA, 5000, Australia.
4
Australian National University Medical School, Australian National University, Canberra, ACT, 2605, Australia.
5
School of Medicine, University of Notre Dame Australia, Sydney, NSW, 2000, Australia.
6
Research Institute for Sports and Exercise, University of Canberra, Canberra, ACT, 2601, Australia.
7
Discipline of Biokinetics, Exercise and Leisure Sciences, School of Health Sciences, University of KwaZulu-Natal, Durban, KwaZulu-Natal, 4000, South Africa.
8
Aston Medical School, Aston University, Birmingham, B4 7ET, UK.
9
Faculty of Health, University of Canberra, Canberra, ACT, 2601, Australia. nenad.naumovski@canberra.edu.au.
10
Collaborative Research in Bioactives and Biomarkers (CRIBB) Group, University of Canberra, Bruce, ACT, 2601, Australia. nenad.naumovski@canberra.edu.au.

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.

KEYWORDS:

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

PMID:
31758301
DOI:
10.1007/s11130-019-00771-5

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