Anti-stress effect of theanine on students during pharmacy practice: positive correlation among salivary α-amylase activity, trait anxiety and subjective stress.
OBJECTIVE
Theanine, an amino acid in tea, has significant anti-stress effect on experimental animals under psychosocial stress. Anti-stress effect of theanine on humans was evaluated in 5th-year university students during pharmacy practice.


METHODS
The study design was a single-blind group comparison and participants (n=20) were randomly assigned to theanine or placebo groups. Theanine or placebo (lactose) tablets (200 mg, twice a day, after breakfast and lunch) were taken from 1 week prior to the pharmacy practice and continued for 10 days in the practice period. To assess the anxiety of the participants, the state-trait anxiety inventory test was carried out before the pharmacy practice. Salivary α-amylase activity (sAA) was measured as a marker of sympathetic nervous system activity.


RESULTS
In the placebo-group, sAA in the morning (pre-practice sAA) was higher than in theanine-group during the pharmacy practice (p=0.032). Subjective stress was significantly lower in the theanine-group than in the placebo-group (p=0.020). These results suggest that theanine intake had anti-stress effect on students. Furthermore, students with higher pre-practice sAA showed significantly higher trait anxiety in both groups (p=0.015). Similarly, higher pre-practice sAA was correlated to shorter sleeping time in both groups (p=0.41×10(-3)).


CONCLUSIONS
Stressful condition increased the level of sAA that was essentially affected by individual trait anxiety. The low levels of pre-practice sAA and subjective stress in the theanine-group suggest that theanine intake suppressed initial stress response of students assigned for a long-term commitment of pharmacy practice.
Laboratory of Bioorganic Chemistry, School of Pharmaceutical Sciences, University of Shizuoka, Shizuoka, Japan. Electronic address: unno@u-shizuoka-ken.ac.jp.
Keiko
K
Unno
Naoki
N
Tanida
Naoto
N
Ishii
Hiroyuki
H
Yamamoto
Kazuaki
K
Iguchi
Minoru
M
Hoshino
Atsushi
A
Takeda
Hayato
H
Ozawa
Tsutomu
T
Ohkubo
Lekh Raj
LR
Juneja
Hiroshi
H
Yamada
D000328:Adult; D004512:Education, Pharmacy; D005260:Female; D005971:Glutamates / Q000627:therapeutic use*; D006801:Humans; D008297:Male; D010919:Placebos; D012463:Saliva / Q000201:enzymology*; D016037:Single-Blind Method; D013315:Stress, Psychological / Q000188:drug therapy*; D013334:Students / Q000523:psychology*; D000078329:Workforce; D055815:Young Adult; D000516:alpha-Amylases / Q000378:metabolism*
D005971:Glutamates; D010919:Placebos; C026166:theanine; D000516:alpha-Amylases
ANS; Anti-stress; Chronic stress; HPA; STAI; Salivary α-amylase; Subjective stress; Theanine; Trait anxiety; VAS; autonomic nervous system; hypothalamus–pituitary–adrenal; post-practice sAA; pre-practice sAA; sAA; sAA in the evening; sAA in the morning; salivary α-amylase activity; the state–trait anxiety inventory; visual analog scales