Document Detail

L-Theanine reduces psychological and physiological stress responses.
MedLine Citation:
PMID:  16930802     Owner:  NLM     Status:  MEDLINE    
L-Theanine is an amino acid contained in green tea leaves which is known to block the binding of L-glutamic acid to glutamate receptors in the brain. Because the characteristics of L-Theanine suggest that it may influence psychological and physiological states under stress, the present study examined these possible effects in a laboratory setting using a mental arithmetic task as an acute stressor. Twelve participants underwent four separate trials: one in which they took L-Theanine at the start of an experimental procedure, one in which they took L-Theanine midway, and two control trials in which they either took a placebo or nothing. The experimental sessions were performed by double-blind, and the order of them was counterbalanced. The results showed that L-Theanine intake resulted in a reduction in the heart rate (HR) and salivary immunoglobulin A (s-IgA) responses to an acute stress task relative to the placebo control condition. Moreover, analyses of heart rate variability indicated that the reductions in HR and s-IgA were likely attributable to an attenuation of sympathetic nervous activation. Thus, it was suggested that the oral intake of L-Theanine could cause anti-stress effects via the inhibition of cortical neuron excitation.
Kenta Kimura; Makoto Ozeki; Lekh Raj Juneja; Hideki Ohira
Publication Detail:
Type:  Journal Article; Randomized Controlled Trial     Date:  2006-08-22
Journal Detail:
Title:  Biological psychology     Volume:  74     ISSN:  0301-0511     ISO Abbreviation:  Biol Psychol     Publication Date:  2007 Jan 
Date Detail:
Created Date:  2006-11-27     Completed Date:  2007-03-13     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0375566     Medline TA:  Biol Psychol     Country:  Netherlands    
Other Details:
Languages:  eng     Pagination:  39-45     Citation Subset:  IM    
Nagoya University Department of Psychology, Chikusa-ku, Nagoya, 464-8601, Japan.
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MeSH Terms
Acute Disease
Brain / metabolism
Cognition / drug effects
Double-Blind Method
Glutamates / pharmacology*
Glutamic Acid / drug effects,  metabolism
Heart Rate / drug effects
Immunoglobulin A / analysis
Neural Inhibition / drug effects
Psychoneuroimmunology / methods*
Receptors, Glutamate / metabolism
Saliva / chemistry
Stress, Psychological / drug therapy*,  immunology*
Sympathetic Nervous System / drug effects
Reg. No./Substance:
0/Glutamates; 0/Immunoglobulin A; 0/Receptors, Glutamate; 3081-61-6/theanine; 56-86-0/Glutamic Acid

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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