Etudes originales

Gargling with green tea does not protect against flu

Gargling with green tea does not protect against flu

 

A clinical trial evaluating the efficacy of gargling with green tea in the prevention of influenza infections among high school students.

A Japanese randomized controlled trial of Ide and colleagues in the journal PLOS published in 2014 ONE assesses the effectiveness of gargling with green tea on the prevention of influenza in high school students.


The Study Rationale

Influenza epidemics are a public health recurrent problem in the world. They cause acute respiratory diseases, they weaken and can lead to serious complications such as pneumonia or encephalitis can lead to death.

The infection in schools is particularly problematic because of the close contact between students that facilitate transmission of the virus between them and, subsequently, their families and the community. Therefore, prevention is an essential measure for public health.

The main strategy for the prevention of influenza infection is now the vaccination. But its effectiveness depends on the virus strain. Non-drug interventions are suggested as the wearing of masks, hand hygiene and gargles. In Asian countries and especially in Japan, gargling is recommended and is commonly practiced. Gargle with water reduces the infection rate of 36%.

Green tea is one of the most consumed in the world DRINKS. It is composed of catechins and théines who have health virtues. The green tea catechins may have antiviral activity against influenza. The influenza infection rates could be reduced.

Catechins and theanine found in green tea could divide by 3 the number of influenza infection.

The Question

Gargles allow green tea prevent influenza infection high school students?

The Method

The Japanese randomized controlled trial of Ide and colleagues, published in the journal PLOS ONE in 2014, evaluates the effectiveness of gargling with green tea on the prevention of influenza compared to gargle with water. The study focused on 757 students aged between 15 and 17 years. The duration of surgery was 90 days during a flu epidemic period. 6 Japanese high schools participated in the study. Each high school student filled a daily questionnaire about the occurrence of influenza infection, preventive measures used (hand hygiene, wearing a mask), adverse events and adherence to their daily gargling. The main measure concerned the number of flu cases confirmed by laboratory tests.

The Non-Pharmacological Intervention (NPI) assessed

Gargles are made with green tea three times a day in high school: the morning arriving after lunch and late afternoon. A 500 ml bottle is provided to participants. Each bottle contains a catechin concentration of 37 mg / dL with approximately 18% epigallocatechin gallate.

Main Results

The study showed no statistical difference between gargling with green tea and gargle with water made 3 times a day for 90 days on the prevention of influenza infections among high school students.

This study does not provide evidence of the effectiveness of gargling with green tea in preventing influenza among high school students.


What it means for General Population

Gargling with green tea, 3 times a day for 90 days, does not reduce influenza infections among high school students.

What it means for Healthcare and Prevention Professionals

Intervention 90-day gargling with green tea among high school students showed no significant differences with water gargles for the prevention of influenza infections.

What it means for Researchers

This trial compared the efficacy gargling with green tea on the prevention of influenza infections compared to gargle with water. The rate of non-adherence was 29% in this study. The adhesion level should be improved in future clinical trials in order to observe any statistical difference between the two groups. A study proposing a double-blind protocol would be probably more effective. It is interesting that the authors did not challenge the assumption, but just methodological problems of demonstration of efficacy.

What it means for Policymakers

Prevention of influenza infection among high school students is essential to reduce the frequency of epidemics and pandemics. Gargling with green tea among high school students, 3 times daily for 90 days have not proved effective in preventing influenza infection. In order to properly assess the effectiveness of such intervention, controlled randomized trials on a larger scale are needed.


The Reference

Ide K, Yamada H, Matsushita K, Ito M, Nojiri K, Toyoizumi K, Matsumoto K, Sameshima Y (2014). Effects of green tea gargling on the prevention of influenza infection in high school students: A randomized controlled study. PLoS ONE, 9, e96373.


Related articles on Blog en Sante ©

Same topic

Same population

Same non-pharmacological intervention


To reference this Blog en Sante © article.

Ninot G (2015). Gargling with green tea does not protect against flu. Blog en Sante, A62.

© Copyright 2015 Gregory Ninot. All rights reserved.

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