Evidence map›Paper›PMID 21338496›Full record

Trial reportBMC complementary and alternative medicine2011

Effects of green tea catechins and theanine on preventing influenza infection among healthcare workers: a randomized controlled trial.

Keiji Matsumoto, Hiroshi Yamada, Norikata Takuma, Hitoshi Niino, Yuko M Sagesaka

Registry-linked trialAbstract readRandomized Controlled Trial
PubMed Full text at PMC Publisher
In one paragraph

Trial report in BMC complementary and alternative medicine, 2011. The graph could read no effect estimate from its abstract, so it casts no vote on the map. It is linked to trial NCT01008020 (A Randomized Controlled Study on the Effects of Tea Catechin Consumption on the Prevention of Influenza Infection in Healthy Adults), which is not on this map. Cited by 49 papers, 6 of them syntheses that pooled it.

0numbers the graph read from it
0cells of the map it votes in
49citing papers in PubMed, 6 pooled it
–field-weighted citation impact
1 · What the graph read from it

What it found

Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.

The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.

2 · The registry

The trial behind it

Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.

NCT01008020 nacompletednot on this map

A Randomized Controlled Study on the Effects of Tea Catechin Consumption on the Prevention of Influenza Infection in Healthy Adults

TypeinterventionalSponsorMasahiro MorikawaRan2009 to 2010Enrolled200ConditionsInfluenza InfectionArmstea catechin extracts
3 · Its place in the literature

Who cites it

49 citing papers in PubMed, 6 syntheses or guidelines pooled it.

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  17. L-Theanine and Immunity: A Review.Molecules (Basel, Switzerland) · 2023
    Review
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4 · The record

Corrections and comments

PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.

5 · Who and what money

Authors and funding

5 authors.

Keiji MatsumotoDepartment of Drug Evaluation & Informatics, Graduate School of Pharmaceutical Sciences, University of Shizuoka, Yada, Suruga-ku, Shizuoka, Japan.
Hiroshi Yamada
Norikata Takuma
Hitoshi Niino
Yuko M Sagesaka

Funding

No grant is acknowledged in the PubMed record.

6 · The paper itself

Abstract

backgroundExperimental studies have revealed that green tea catechins and theanine prevent influenza infection, while the clinical evidence has been inconclusive. This study was conducted to determine whether taking green tea catechins and theanine can clinically prevent influenza infection.

methodsDESIGN, SETTING, AND

participantsA randomized, double-blind, placebo-controlled trial of 200 healthcare workers conducted for 5 months from November 9, 2009 to April 8, 2010 in three healthcare facilities for the elderly in Higashimurayama, Japan.

interventionsThe catechin/theanine group received capsules including green tea catechins (378 mg/day) and theanine (210 mg/day). The control group received placebo.

main outcome measuresThe primary outcome was the incidence of clinically defined influenza infection. Secondary outcomes were (1) laboratory-confirmed influenza with viral antigen measured by immunochromatographic assay and (2) the time for which the patient was free from clinically defined influenza infection, i.e., the period between the start of intervention and the first diagnosis of influenza infection, based on clinically defined influenza infection.

resultsEligible healthcare workers (n = 197) were enrolled and randomly assigned to an intervention; 98 were allocated to receive catechin/theanine capsules and 99 to placebo. The incidence of clinically defined influenza infection was significantly lower in the catechin/theanine group (4 participants; 4.1%) compared with the placebo group (13 participants; 13.1%) (adjusted OR, 0.25; 95% CI, 0.07 to 0.76, P = 0.022). The incidence of laboratory-confirmed influenza infection was also lower in the catechin/theanine group (1 participant; 1.0%) than in the placebo group (5 participants; 5.1%), but this difference was not significant (adjusted OR, 0.17; 95% CI, 0.01 to 1.10; P = 0.112). The time for which the patient was free from clinically defined influenza infection was significantly different between the two groups (adjusted HR, 0.27; 95% CI, 0.09 to 0.84; P = 0.023).

conclusionsAmong healthcare workers for the elderly, taking green tea catechins and theanine may be effective prophylaxis for influenza infection.

trial registrationClinicalTrials (NCT): NCT01008020.

Indexed as

Health PersonnelPhytotherapyAdultCamellia sinensisCatechinDouble-Blind MethodGlutamatesHumansIncidenceInfluenza, HumanPlant ExtractsTeaCatechinGlutamatesPlant ExtractsTeatheanine

Identifiers

PMID21338496
PMCPMC3049752

What OpenQuestion holds

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Registered trials

Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.