Skip to main content

Advertisement

SpringerLink
Log in

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

  • Review Article
  • Published:
Plant Foods for Human Nutrition Aims and scope Submit manuscript

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.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Log in via an institution

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Institutional subscriptions

Fig. 1
Fig. 2

Similar content being viewed by others

Abbreviations

L-THE:

L-Theanine

PRISMA:

Preferred Reporting Items for Systematic Reviews and Meta-Analyses

RCT:

Randomised Controlled Trial

HPA:

Hypothalamic Pituitary Adrenal

HR:

Heart Rate

HRV:

Heart Rate Variability

POMS:

Profile of Mood States

VAS:

Visual Analog Scale

STAI:

State-Trait Anxiety Inventory

BAI:

Beck’s Anxiety Inventory

MAPS:

Mood, Alertness and Physical Symptoms Questionnaire

DASS:

Depression Anxiety and Stress Scale

VPT:

Visual Probe Task

VAMS:

Visual Analogue Mood Scale

HARS:

Hamilton Anxiety Rating Scale

sAA:

salivary Alpha-Amylase (sAA)

s-IgA:

Salivary Immunoglobulin A

BP:

Blood Pressure

References

  1. World Health Organization (2017) Depression and other common mental disorders: Global health estimates. World Health Organization, Geneva

    Google Scholar 

  2. McEwen BS (2000) The neurobiology of stress: from serendipity to clinical relevance. Brain Res 886(1–2):172–189

    CAS  PubMed  Google Scholar 

  3. Pan Y, Cai W, Cheng Q et al (2015) Association between anxiety and hypertension: a systematic review and meta-analysis of epidemiological studies. Neuropsych Dis Treat 11:1121–1130

    Google Scholar 

  4. Hagstrom E, Norlund F, Stebbins A et al (2018) Psychosocial stress and major cardiovascular events in patients with stable coronary heart disease. J Intern Med 283(1):83–92

    CAS  PubMed  Google Scholar 

  5. Fitzsimmons EE, Bardone-Cone AM (2011) Coping and social support as potential moderators of the relation between anxiety and eating disorder symptomatology. Eat Behav 12(1):21–28

    PubMed  Google Scholar 

  6. Myers B, Greenwood-Van Meerveld B (2009) Role of anxiety in the pathophysiology of irritable bowel syndrome: importance of the amygdala. Front Neurosci 3:47

    PubMed  PubMed Central  Google Scholar 

  7. Durand MV, Barlow DH (2010) Essentials of abnormal psychology. 5th edn. Wadsworth Cengage Learning

  8. Spielberger CD (1972) Profile of mood states. Prof Psychol 3(4):387–388

    Google Scholar 

  9. Pfennings L, Cohen L, van der Ploeg H (1995) Preconditions for sensitivity in measuring change: visual analogue scales compared to rating scales in a Likert format. Psychol Rep 77(2):475–480

    CAS  PubMed  Google Scholar 

  10. Hedberg AG (1972) State-trait anxiety inventory. Prof Psych 3(4):389–390

    Google Scholar 

  11. Dozois DJA, Dobson KS, Ahnberg JL (1998) A psychometric evaluation of the Beck depression inventory-II. Psychol assessment 10(2):83–89

    Google Scholar 

  12. Matthews KA, Woodall KL, Allen MT (1993) Cardiovascular reactivity to stress predicts future blood pressure status. Hypertension 22(4):479–485

    CAS  PubMed  Google Scholar 

  13. Gorman JM, Sloan RP (2000) Heart rate variability in depressive and anxiety disorders. Am Heart J 140(4 Suppl):77–83

    CAS  PubMed  Google Scholar 

  14. Nater UM, La Marca R, Florin L et al (2006) Stress-induced changes in human salivary alpha-amylase activity - associations with adrenergic activity. Psychoneuroendocrino 31(1):49–58

    CAS  Google Scholar 

  15. McCabe D, Lisy K, Lockwood C et al. (2017) The impact of essential fatty acid, B vitamins, vitamin C, magnesium and zinc supplementation on stress levels in women: a systematic review. JBI Database System Rev Implement Rep 15(2):402–453. https://doi.org/10.11124/JBISRIR-2016-002965

    PubMed  Google Scholar 

  16. Williams J, Sergi D, McKune AJ et al (2019) The beneficial health effects of green tea amino acid l-theanine in animal models: promises and prospects for human trials. Phytother Res 3(3):571–583

    PubMed  Google Scholar 

  17. Liu J, Xing J, Fei Y (2008) Green tea (Camellia sinensis) and cancer prevention: a systematic review of randomized trials and epidemiological studies. Chin Med 3:12

    PubMed  PubMed Central  Google Scholar 

  18. Katergaris N, Dufficy L, Roach PD et al (2015) Green tea catechins as neuroprotective agents: systematic review of the literature in animal pre-clinical trials. AFTNS Open J 1(2):48–57

    Google Scholar 

  19. Bursill CA, Abbey M, Roach PD (2007) A green tea extract lowers plasma cholesterol by inhibiting cholesterol synthesis and upregulating the LDL receptor in the cholesterol-fed rabbit. Atherosclerosis 193(1):86–93

    CAS  PubMed  Google Scholar 

  20. Bursill CA, Roach PD (2007) A green tea catechin extract upregulates the hepatic low-density lipoprotein receptor in rats. Lipids 42(7):621–627

    CAS  PubMed  Google Scholar 

  21. Reto M, Figueira ME, Filipe HM et al (2007) Chemical composition of green tea (Camellia sinensis) infusions commercialized in Portugal. Plant Foods Hum Nutr 62(4):139–144

    CAS  PubMed  Google Scholar 

  22. Vuong QV (2014) Epidemiological evidence linking tea consumption to human health: a review. Crit Rev Food Sci Nutr 54(4):523–536

    CAS  PubMed  Google Scholar 

  23. Naumovski N, Foscolou A, D'Cunha NM et al. (2019) The association between green and black tea consumption on successful aging: a combined analysis of the ATTICA and MEDiterranean ISlands (MEDIS) Epidemiological Studies. Molecules 24(10):E1862

    CAS  PubMed Central  Google Scholar 

  24. Crichton GE, Bryan J, Murphy KJ (2013) Dietary antioxidants, cognitive function and dementia-a systematic review. Plant Foods Hum Nutr 68(3):279–292

    CAS  PubMed  Google Scholar 

  25. Naumovski N, Blades BL, Roach PD (2015) Food inhibits the oral bioavailability of the major green tea antioxidant epigallocatechin gallate in humans. Antioxidants 4(2):373–393

    CAS  PubMed  PubMed Central  Google Scholar 

  26. Yao LH, Jiang YM, Shi J et al (2004) Flavonoids in food and their health benefits. Plant Foods Hum Nutr 59(3):113–122

    CAS  PubMed  Google Scholar 

  27. Nehlig A, Daval JL, Debry G (1992) Caffeine and the central nervous system: mechanisms of action, biochemical, metabolic and psychostimulant effects. Brain Res Brain Res Rev 17(2):139–170

    CAS  PubMed  Google Scholar 

  28. Vuong QV, Bowyer MC, Roach PD (2011) L-Theanine: properties, synthesis and isolation from tea. J Sci Food Agric 91(11):1931–1939

    CAS  PubMed  Google Scholar 

  29. Williams J, Kellett J, Roach PD et al (2016) L-theanine as a functional food additive: its role in disease prevention and health promotion. Beverages 2(13):1–16

    Google Scholar 

  30. Eschenauer G, Sweet BV (2006) Pharmacology and therapeutic uses of theanine. Am J Health Syst Pharm 63(1):26, 28–30

    Google Scholar 

  31. Cooper R (2012) Green tea and theanine: health benefits. Int J Food Sci Nutr 63(Suppl 1):90–97

    CAS  PubMed  Google Scholar 

  32. Nobre AC, Rao A, Owen GN (2008) L-theanine, a natural constituent in tea, and its effect on mental state. Asia Pac J Clin Nutr 17(Suppl 1):167–168

    CAS  PubMed  Google Scholar 

  33. Desai MJ, Gill MS, Hsu WH et al (2005) Pharmacokinetics of theanine enantiomers in rats. Chirality 17(3):154–162

    CAS  PubMed  Google Scholar 

  34. Yan Q, Tong H, Tang S et al (2017) L-theanine administration modulates the absorption of dietary nutrients and expression of transporters and receptors in the intestinal mucosa of rats. Biomed Res Int 2017:9747256

    PubMed  PubMed Central  Google Scholar 

  35. Scheid L, Ellinger S, Alteheld B et al (2012) Kinetics of L-theanine uptake and metabolism in healthy participants are comparable after ingestion of L-theanine via capsules and green tea. J Nutr 142(12):2091–2096

    CAS  PubMed  Google Scholar 

  36. Yokogoshi H, Kobayashi M, Mochizuki M et al (1998) Effect of theanine, r-glutamylethylamide, on brain monoamines and striatal dopamine release in conscious rats. Neurochem Res 23(5):667–673

    CAS  PubMed  Google Scholar 

  37. Turkozu D, Sanlier N (2017) L-theanine, unique amino acid of tea, and its metabolism, health effects, and safety. Crit Rev Food Sci Nutr 57(8):1681–1687

    CAS  PubMed  Google Scholar 

  38. Rogers PJ, Smith JE, Heatherley SV et al (2008) Time for tea: mood, blood pressure and cognitive performance effects of caffeine and theanine administered alone and together. Psychopha 195(4):569–577

    CAS  Google Scholar 

  39. Camfield DA, Stough C, Farrimond J et al (2014) Acute effects of tea constituents L-theanine, caffeine, and epigallocatechin gallate on cognitive function and mood: a systematic review and meta-analysis. Nutr Rev 72(8):507–522

    PubMed  Google Scholar 

  40. Cicero AFG, Fogacci F, Banach M (2018) Botanicals and phytochemicals active on cognitive decline: the clinical evidence. Pharmacol Res 130:204–212

    CAS  PubMed  Google Scholar 

  41. Haskell CF, Kennedy DO, Milne AL et al (2008) The effects of L-theanine, caffeine and their combination on cognition and mood. Biol Psychol 77(2):113–122

    PubMed  Google Scholar 

  42. Moher D, Liberati A, Tetzlaff J et al (2009) Preferred reporting items for systematic reviews and meta-analyses: the PRISMA statement. J Clin Epidemiol 62(10):1006–1012

    Google Scholar 

  43. Clifton PM, Condo D, Keogh JB (2014) Long term weight maintenance after advice to consume low carbohydrate, higher protein diets-a systematic review and meta analysis. NMCD 24(3):224–235

    CAS  PubMed  Google Scholar 

  44. Sarris J, Byrne GJ, Cribb L et al (2018) L-theanine in the adjunctive treatment of generalised anxiety disorder: a double-blind, randomised, placebo-controlled trial. J Psychiat Res 110:31–37

    PubMed  Google Scholar 

  45. Higgins JPT, Altman DG, Sterne JAC (2011) Chapter 8: Assessing risk of bias in included studies. In: Higgins J, Thomas J (eds) Cochrane handbook for systematic reviews of interventions version 5.1.0 The Cochrane Collaboration

  46. Higashiyama A, Htay HH, Ozeki M et al (2011) Effects of L-theanine on attention and reaction time response. J Funct Food 3(3):171–178

    CAS  Google Scholar 

  47. Kimura K, Ozeki M, Juneja LR et al (2007) L-theanine reduces psychological and physiological stress responses. Biol Psychol 74(1):39–45

    PubMed  Google Scholar 

  48. Lu K, Gray MA, Oliver C et al (2004) The acute effects of L-theanine in comparison with alprazolam on anticipatory anxiety in humans. Hum Psychopharm Clin 19(7):457–465

    CAS  Google Scholar 

  49. Ritsner MS, Miodownik C, Ratner Y et al (2011) L-theanine relieves positive, activation, and anxiety symptoms in patients with schizophrenia and schizoaffective disorder: an 8-week, randomized, double-blind, placebo-controlled, 2-center study. J Clin Psychiatry 72(1):34–42

    CAS  PubMed  Google Scholar 

  50. Unno K, Tanida N, Ishii N et al (2013) Anti-stress effect of theanine on students during pharmacy practice: positive correlation among salivary alpha-amylase activity, trait anxiety and subjective stress. Pharmacol Biochem Behav 111:128–135

    CAS  PubMed  Google Scholar 

  51. White DJ, de Klerk S, Woods W et al. (2016) Anti-stress, behavioural and magnetoencephalography effects of an L-theanine-based nutrient drink: a randomised, double-blind, placebo-controlled, crossover trial. Nutrients 8(1):E53

    PubMed Central  Google Scholar 

  52. Yoto A, Motoki M, Murao S et al (2012) Effects of L-theanine or caffeine intake on changes in blood pressure under physical and psychological stresses. J Physiol Anthropol 31:28

    PubMed  PubMed Central  Google Scholar 

  53. Helton SG, Lohoff FW (2015) Serotonin pathway polymorphisms and the treatment of major depressive disorder and anxiety disorders. Pharmacogenomics 16(5):541–553

    CAS  PubMed  Google Scholar 

  54. Lyon MR, Kapoor MP, Juneja LR (2011) The effects of L-theanine (Suntheanine(R)) on objective sleep quality in boys with attention deficit hyperactivity disorder (ADHD): a randomized, double-blind, placebo-controlled clinical trial. Altern Med Rev 16(4):348–354

    PubMed  Google Scholar 

  55. Alteheld B, Scheid L, Stehle P et al (2012) Kinetics of L-theanine uptake and metabolism in healthy participants are comparable after ingestion of L-theanine via capsules and green tea. J Nutr 142(12):2091–2096

    PubMed  Google Scholar 

  56. Yuen EY, Liu W, Karatsoreos IN et al (2009) Acute stress enhances glutamatergic transmission in prefrontal cortex and facilitates working memory. Proc Natl Acad Sci USA 106(33):14075–14079

    CAS  PubMed  Google Scholar 

  57. Popoli M, Yan Z, McEwen BS et al (2011) The stressed synapse: the impact of stress and glucocorticoids on glutamate transmission. Nat Rev Neurosci 13(1):22–37

    PubMed  PubMed Central  Google Scholar 

  58. Kakuda T, Nozawa A, Sugimoto A et al (2002) Inhibition by theanine of binding of [3H]AMPA, [3H]kainate, and [3H]MDL 105,519 to glutamate receptors. Biosci Biotechnol Biochem 66(12):2683–2686

    CAS  PubMed  Google Scholar 

  59. Unno K, Iguchi K, Tanida N et al (2013) Ingestion of theanine, an amino acid in tea, suppresses psychosocial stress in mice. Exp Physiol 98(1):290–303

    CAS  PubMed  Google Scholar 

  60. Baas JM, Grillon C, Bocker KB et al (2002) Benzodiazepines have no effect on fear-potentiated startle in humans. Psychopha 161(3):233–247

    CAS  Google Scholar 

  61. Juneja R, Djong-Chi C, Tsutomu O et al (1999) L-theanine—a unique amino acid of green tea and its relaxation effect in humans. Trends Food Sci Tech 10(6–7):199–204

    CAS  Google Scholar 

  62. Hintikka J, Tolmunen T, Honkalampi K et al (2005) Daily tea drinking is associated with a low level of depressive symptoms in the Finnish general population. Eur J Epidemiol 20(4):359–363

    CAS  PubMed  Google Scholar 

  63. Wang RS, Kies C (1991) Niacin, thiamin, iron and protein status of humans as affected by the consumption of tea (Camellia sinensis) infusions. Plant Foods Hum Nutr 41(4):337–353

    CAS  PubMed  Google Scholar 

  64. Koo SI, Noh SK (2007) Green tea as inhibitor of the intestinal absorption of lipids: potential mechanism for its lipid-lowering effect. J Nutr Biochem 18(3):179–183

    CAS  PubMed  PubMed Central  Google Scholar 

  65. D’Cunha NM, Georgousopoulou EN, Dadigamuwage L et al (2018) Effect of long-term nutraceutical and dietary supplement use on cognition in the elderly: a 10-year systematic review of randomised controlled trials. Brit J Nutr 119(3):280–298

    PubMed  Google Scholar 

  66. Barnett H, D'Cunha NM, Geogousopoulou E et al (2017) Effect of folate supplementation on inflammatory markers in individuals susceptible to depression: a systematic review. ERHM 2:86–100

    Google Scholar 

Download references

Acknowledgements

Dr. Paul Roach for providing initial feedback on the manuscript.

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.

Author information

Author notes

  1. Jackson L. Williams and Julian M. Everett contributed equally to this work.

Authors and Affiliations

  1. Faculty of Health, University of Canberra, Canberra, ACT, 2601, Australia

    Jackson L. Williams, Julian M. Everett, Nathan M. D’Cunha, Richard J. Keegan, Andrew J. McKune, Nicola Anstice & Nenad Naumovski

  2. Collaborative Research in Bioactives and Biomarkers (CRIBB) Group, University of Canberra, Bruce, ACT, 2601, Australia

    Jackson L. Williams, Nathan M. D’Cunha, Andrew J. McKune, Duane D. Mellor, Nicola Anstice & Nenad Naumovski

  3. Nutrition & Health Substantiation Group, Nutrition and Health Program, Health and Biosecurity, Commonwealth Scientific and Industrial Research Organisation (CSIRO), Adelaide, SA, 5000, Australia

    Domenico Sergi

  4. Australian National University Medical School, Australian National University, Canberra, ACT, 2605, Australia

    Ekavi N. Georgousopoulou

  5. School of Medicine, University of Notre Dame Australia, Sydney, NSW, 2000, Australia

    Ekavi N. Georgousopoulou

  6. Research Institute for Sports and Exercise, University of Canberra, Canberra, ACT, 2601, Australia

    Richard J. Keegan & Andrew J. McKune

  7. Discipline of Biokinetics, Exercise and Leisure Sciences, School of Health Sciences, University of KwaZulu-Natal, Durban, KwaZulu-Natal, 4000, South Africa

    Andrew J. McKune

  8. Aston Medical School, Aston University, Birmingham, B4 7ET, UK

    Duane D. Mellor

Authors
  1. Jackson L. Williams
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. Julian M. Everett
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. Nathan M. D’Cunha
    View author publications

    You can also search for this author in PubMed Google Scholar

  4. Domenico Sergi
    View author publications

    You can also search for this author in PubMed Google Scholar

  5. Ekavi N. Georgousopoulou
    View author publications

    You can also search for this author in PubMed Google Scholar

  6. Richard J. Keegan
    View author publications

    You can also search for this author in PubMed Google Scholar

  7. Andrew J. McKune
    View author publications

    You can also search for this author in PubMed Google Scholar

  8. Duane D. Mellor
    View author publications

    You can also search for this author in PubMed Google Scholar

  9. Nicola Anstice
    View author publications

    You can also search for this author in PubMed Google Scholar

  10. Nenad Naumovski
    View author publications

    You can also search for this author in PubMed Google Scholar

Corresponding author

Correspondence to Nenad Naumovski.

Ethics declarations

Conflict of Interest

The authors declare that they have no conflicts of interest.

Additional information

Publisher’s Note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Rights and permissions

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Williams, J.L., Everett, J.M., D’Cunha, N.M. et al. 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 75, 12–23 (2020). https://doi.org/10.1007/s11130-019-00771-5

Download citation

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1007/s11130-019-00771-5

Keywords

Search

Navigation