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Biol Pharm Bull. 2017;40(6):902-909. doi: 10.1248/bpb.b17-00141.

Anti-stress Effect of Green Tea with Lowered Caffeine on Humans: A Pilot Study.

Author information

1
Department of Neurophysiology, School of Pharmaceutical Sciences, University of Shizuoka.
2
Tea Science Center, Graduate Division of Nutritional and Environmental Sciences, University of Shizuoka.
3
Division of Drug Evaluation & Informatics, School of Pharmaceutical Sciences, University of Shizuoka.
4
Medicinal Chemistry of Natural Products, School of Pharmaceutical Sciences, University of Shizuoka.
5
Pharmaceutical Engineering Laboratory, School of Pharmaceutical Sciences, University of Shizuoka.
6
Department of Functional Plant Physiology, Faculty of Agriculture, Shizuoka University.

Abstract

Theanine, an amino acid in tea, has significant anti-stress effects on animals and humans. However, the effect of theanine was blocked by caffeine and gallate-type catechins, which are the main components in tea. We examined the anti-stress effect of green tea with lowered caffeine, low-caffeine green tea, on humans. The study design was a single-blind group comparison and participants (n=20) were randomly assigned to low-caffeine or placebo tea groups. These teas (≥500 mL/d), which were eluted with room temperature water, were taken from 1 week prior to pharmacy practice and continued for 10 d in the practice period. The participants ingested theanine (ca. 15 mg/d) in low-caffeine green tea. To assess the anxiety of participants, the state-trait anxiety inventory test was used before pharmacy practice. The subjective stress of students was significantly lower in the low-caffeine-group than in the placebo-group during pharmacy practice. The level of salivary α-amylase activity, a stress marker, increased significantly after daily pharmacy practice in the placebo-group but not in the low-caffeine-group. These results suggested that the ingestion of low-caffeine green tea suppressed the excessive stress response of students. This study was registered at the University Hospital Medical Information Network (ID No. UMIN14942).

KEYWORDS:

anti-stress effect; clinical study; green tea; salivary α-amylase; theanine

PMID:
28566632
DOI:
10.1248/bpb.b17-00141
[Indexed for MEDLINE]
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