---
title: "Four Weeks of L-Theanine Lowered Stress Scores"
url: https://stacklist.com/card/2f27ea5e-ae1a-4589-956e-817e39ab33a0
source_url: "https://pubmed.ncbi.nlm.nih.gov/31623400/"
stack: https://stacklist.com/c/education/stack/ed5a3ae2-37d9-4b9f-acfb-16fc78c07ec8
summary: "L-theanine supplementation at 200 mg/day for four weeks significantly reduced stress-related symptoms including depression, anxiety, and sleep disturbances in 30 healthy adults. The treatment also improved cognitive functions, particularly verbal fluency and executive function, suggesting L-theanine's potential for promoting mental health in populations with stress-related ailments."
tags: "l-theanine, stress-reduction, cognitive-function, clinical-trial, sleep-quality, mental-health"
key_entities: "L-theanine (concept), stress-related symptoms (concept), cognitive function (concept), Pittsburgh Sleep Quality Index (concept), Yasukawa Z. (person), Ozeki M. (person), Taiyo Kagaku Co., Ltd. (organization)"
classification: "analysis"
content_hash: "sha256:b7b6094537caf95b2651111066f60cdc9a3d6733cce737802ad8632552d09741"
acp_version: "0.2"
token_counts_approximate: 1550
visibility: public
agent_accessible: true
status: "final"
---

# Four Weeks of L-Theanine Lowered Stress Scores

Full text links Cite Display options Display options Format Abstract PubMed PMID Linked Discoveries Abstract This randomized, placebo-controlled, crossover, and double-blind trial aimed to examine the possible effects of four weeks L-theanine administration on stress-related symptoms and cognitive functions in healthy adults. Participants were 30 individuals (nine men and 21 women; age: 48.3 ± 11.9 years) who had no major psychiatric illness. L-theanine (200 mg/day) or placebo tablets were randomly and blindly assigned for four-week administration. For stress-related symptoms, Self-rating Depression Scale, State-Trait Anxiety Inventory-trait, and Pittsburgh Sleep Quality Index (PSQI) scores decreased after L-theanine administration ( p = 0.019, 0.006, and 0.013, respectively). The PSQI subscale scores for sleep latency, sleep disturbance, and use of sleep medication reduced after L-theanine administration, compared to the placebo administration (all p < 0.05). For cognitive functions, verbal fluency and executive function scores improved after L-theanine administration ( p = 0.001 and 0.031, respectively). Stratified analyses revealed that scores for verbal fluency ( p = 0.002), especially letter fluency ( p = 0.002), increased after L-theanine administration, compared to the placebo administration, in individuals who were sub-grouped into the lower half by the median split based on the mean pretreatment scores. Our findings suggest that L-theanine has the potential to promote mental health in the general population with stress-related ailments and cognitive impairments. Keywords: L-theanine; cognition; emotion; sleep; stress. PubMed Disclaimer Conflict of interest statement Yasukawa Z. and Ozeki M. are employees of Taiyo Kagaku Co., Ltd. which supplied the L-theanine and placebo tablets used in this trial. Figures Figure 1 Stress-related symptom scores after 4… Figure 1 Stress-related symptom scores after 4 weeks L-theanine or placebo administration. The Wilcoxon signed-rank… Figure 1 Stress-related symptom scores after 4 weeks L-theanine or placebo administration. The Wilcoxon signed-rank test revealed that the Self-rating Depression Scale, State-Trait Anxiety Inventory-trait, and Pittsburgh Sleep Quality Index scores were significantly decreased in the L-theanine administration ( n = 30), while there was no significant change in the placebo administration ( n = 30). * p < 0.05, ** p < 0.01. N.S., not significant. Figure 2 Cognitive function scores after 4… Figure 2 Cognitive function scores after 4 weeks L-theanine or placebo administration. The Wilcoxon signed-rank… Figure 2 Cognitive function scores after 4 weeks L-theanine or placebo administration. The Wilcoxon signed-rank test revealed that the Brief Assessment of Cognition in Schizophrenia (BACS) verbal fluency and executive function scores were significantly decreased in the L-theanine administration ( n = 30), while there was no significant change in the placebo administration ( n = 30). * p < 0.05, ** p < 0.01. N.S.: Not significant. See this image and copyright information in PMC References Vuong Q.V. Epidemiological evidence linking tea consumption to human health: A review. Crit. Rev. Food Sci. Nutr. 2014;54:523–536. doi: 10.1080/10408398.2011.594184. - DOI - PubMed Saeed M., Naveed M., Arif M., Kakar M.U., Manzoor R., El-Hack M.E.A., Alagawany M., Tiwari R., Khandia R., Munjal A., et al. Green tea (Camellia sinensis) and l-theanine: Medicinal values and beneficial applications in humans—A comprehensive review. Biomed. Pharmacother. 2017;95:1260–1275. doi: 10.1016/j.biopha.2017.09.024. - DOI - PubMed Sharma E., Joshi R., Gulati A. l-theanine: An astounding sui generis integrant in tea. Food Chem. 2018;242:601–610. doi: 10.1016/j.foodchem.2017.09.046. - DOI - PubMed Kakuda T. Neuroprotective effects of theanine and its preventive effects on cognitive dysfunction. Pharmacol. Res. 2011;64:162–168. doi: 10.1016/j.phrs.2011.03.010. - DOI - PubMed Sebih F., Rousset M., Bellahouel S., Rolland M., de Ferreira M.C.J., Guiramand J., Cohen-Solal C., Barbanel G., Cens T., Abouazza M., et al. Characterization of l-theanine excitatory actions on hippocampal neurons: Toward the generation of novel N-Methyl-d-aspartate receptor modulators based on its backbone. ACS Chem. Neurosci. 2017;8:1724–1734. doi: 10.1021/acschemneuro.7b00036. - DOI - PubMed Show all 61 references Publication types Randomized Controlled Trial Actions Search in PubMed Search in MeSH Add to Search MeSH terms Adult Actions Search in PubMed Search in MeSH Add to Search Anxiety / drug therapy Actions Search in PubMed Search in MeSH Add to Search Body Mass Index Actions Search in PubMed Search in MeSH Add to Search Cognition / drug effects* Actions Search in PubMed Search in MeSH Add to Search Cross-Over Studies Actions Search in PubMed Search in MeSH Add to Search Depression / drug therapy Actions Search in PubMed Search in MeSH Add to Search Double-Blind Method Actions Search in PubMed Search in MeSH Add to Search Female Actions Search in PubMed Search in MeSH Add to Search Glutamates / administration & dosage* Actions Search in PubMed Search in MeSH Add to Search Humans Actions Search in PubMed Search in MeSH Add to Search Male Actions Search in PubMed Search in MeSH Add to Search Middle Aged Actions Search in PubMed Search in MeSH Add to Search Placebos Actions Search in PubMed Search in MeSH Add to Search Sleep Wake Disorders / drug therapy Actions Search in PubMed Search in MeSH Add to Search Stress, Psychological / complications* Actions Search in PubMed Search in MeSH Add to Search Stress, Psychological / psychology* Actions Search in PubMed Search in MeSH Add to Search Substances Glutamates Actions Search in PubMed Search in MeSH Add to Search Placebos Actions Search in PubMed Search in MeSH Add to Search theanine Actions Search in PubMed Search in MeSH Add to Search Grants and funding None/Funding received from Taiyo Kagaku Co., Ltd., Mie, Japan. 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