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Gargling With Green Tea for Prophylaxis of Influenza Infection in Teenagers

The recruitment status of this study is unknown. The completion date has passed and the status has not been verified in more than two years.
Verified February 2013 by University of Shizuoka.
Recruitment status was:  Recruiting
Information provided by (Responsible Party):
University of Shizuoka Identifier:
First received: October 19, 2010
Last updated: February 12, 2013
Last verified: February 2013
Experimental and clinical studies in adults have reported that green tea catechins prevent influenza infection. In this clinical randomized study, the investigators aimed to determine the effects of gargling with green tea on the prophylaxis of influenza infection among high school teenagers.

Condition Intervention Phase
Influenza Infection Dietary Supplement: green tea Phase 3

Study Type: Interventional
Study Design: Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: None (Open Label)
Primary Purpose: Prevention
Official Title: Effects of Gargling With Green Tea on Preventing Influenza Infection Among High School Students: A Randomized Clinical Study

Resource links provided by NLM:

Further study details as provided by University of Shizuoka:

Primary Outcome Measures:
  • the incidence rates of influenza infection [ Time Frame: Until 3 months gargling ]

Secondary Outcome Measures:
  • severity of influenza symptoms [ Time Frame: until 3 months gargling ]
  • influenza-free time during the study period [ Time Frame: until 3 months gargling ]
  • incidence of complications [ Time Frame: until 3 months gargling ]
  • incidence rates of upper respiratory tract infections [ Time Frame: until 3 months gargling ]
  • incidence of days of absence from school [ Time Frame: until 3 months gargling ]
  • occurrence of the adverse events [ Time Frame: until 3 months gargling ]

Estimated Enrollment: 640
Study Start Date: November 2010
Estimated Study Completion Date: August 2014
Estimated Primary Completion Date: April 2014 (Final data collection date for primary outcome measure)
Arms Assigned Interventions
Experimental: Green tea
Gargling with green tea
Dietary Supplement: green tea
Gargling three times daily for 90 days
Active Comparator: water
Gargling with water
Dietary Supplement: green tea
Gargling three times daily for 90 days

Detailed Description:

Influenza infection is the principal cause of acute respiratory illnesses and occurs in epidemic or pandemic worldwide. It spreads easily among high school students and from them to the rest of the community; therefore the prevention of influenza is very important.

Experimental studies have revealed that some components of green tea can prevent influenza infection in vitro. In clinically, gargling with green tea catechins has been reported to have possibilities to preventing influenza infection in adults; however, little clinical evidence in teenagers has so far been existed. Based on this background, the investigators designed a randomized study to evaluate the clinical efficacy of gargling with green tea in preventing influenza infection among high school students.


Ages Eligible for Study:   15 Years to 20 Years   (Child, Adult)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   Yes

Inclusion Criteria:

  • aged from 15 to 20 years
  • obtained written informed consent from both the student and parent before participation
  • possible to gargle during 90 days
  • possible to fill in questionnaire

Exclusion Criteria:

  • Possessing allergy to green tea
  • Possessing history of influenza infection within 6 months before entering the study
  • Possessing severe immune disease or whole body infection
  • severe cardiac, respiratory, renal, or hepatic dysfunction
  • diagnosed as inadequate to participate in the study by student doctor
  Contacts and Locations
Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study. To learn more about this study, you or your doctor may contact the study research staff using the Contacts provided below. For general information, see Learn About Clinical Studies.

Please refer to this study by its identifier: NCT01225770

Contact: Hiroshi Yamada, MD, PhD +81-54-264-5762
Contact: Keiji Matsumoto, MS +81-54-264-5770

University of Shizuoka Recruiting
Shizuoka, Japan
Contact: Hiroshi Yamada, MD, PhD    +81-54-264-5762   
Contact: Keiji Matsumoto, Ms    +81-54-264-5770   
Principal Investigator: Hiroshi Yamada, MD, PhD         
Sponsors and Collaborators
University of Shizuoka
Study Chair: Hiroshi Yamada, MD, PhD University of Shizuoka
  More Information

Publications automatically indexed to this study by Identifier (NCT Number):
Responsible Party: University of Shizuoka Identifier: NCT01225770     History of Changes
Other Study ID Numbers: CT2010001
Study First Received: October 19, 2010
Last Updated: February 12, 2013

Keywords provided by University of Shizuoka:
green tea
Respiratory Tract Infections
high school students

Additional relevant MeSH terms:
Communicable Diseases
Influenza, Human
Orthomyxoviridae Infections
RNA Virus Infections
Virus Diseases
Respiratory Tract Infections
Respiratory Tract Diseases processed this record on August 18, 2017