The impact of Uva tea extract capsule consumption on psychological stress: A randomized, double-blind, placebo-controlled, crossover trial

Naoko Takamizawa, Shirrichiro Yamashita, Naoko Suzuki, Kazuo Yamamoto, Haruko Takeyama, Kazunaga Yazawa, Tsuyoshi Takara

Research output: Contribution to journalArticle


Objectives: This study aims to investigate the effects of consuming Uva tea extract capsules by decreasing the psychological stress in Japanese subjects. Methods: Twenty-two eligible subjects were randomly assigned to sequences either an Uva tea extract (Uva) or a placebo, with each member in both sequences consuming appropriate capsules. Each intervention lasted for 3 weeks, with the 2-week washout period. We assessed the autonomic nervous activity and mood state of subjects in both sequences. Results: The Uva capsule intake revealed trends toward significantly lower the ratio between low and high frequency components and significantly lower tension-anxiety compared with the placebo capsule intake. Furthermore, subjects with the body mass index <25, especially the Uva capsule intake, exhibited the dominant parasympathetic nervous system. Conclusions: Hence, this study suggests that the 3-week Uva capsule consumption could modulate the automatic nervous system and ease tension and anxiety. Trial Registration University Hospital Medical Information Network; UMIN000027549 Foundation There was no funding.

Original languageEnglish
Pages (from-to)2001-2010
Number of pages10
JournalJapanese Pharmacology and Therapeutics
Issue number12
Publication statusPublished - 2018 Jan 1



  • Autonomic nervous activity
  • Parasympathetic nervous system
  • Polyphenol
  • Theaflavin
  • Uva tea

ASJC Scopus subject areas

  • Pharmacology
  • Pharmacology (medical)

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