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

Abstract

BACKGROUND

Experimental 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.

INTERVENTIONS

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

MAIN OUTCOME MEASURES

The 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.

RESULTS

Eligible 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).

CONCLUSIONS

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

TRIAL REGISTRATION

ClinicalTrials (NCT): NCT01008020.

Authors+Show Affiliations

Department of Drug Evaluation & Informatics, Graduate School of Pharmaceutical Sciences, University of Shizuoka, Yada, Suruga-ku, Shizuoka, Japan.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Randomized Controlled Trial
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

21338496

Citation

Matsumoto, Keiji, et al. "Effects of Green Tea Catechins and Theanine On Preventing Influenza Infection Among Healthcare Workers: a Randomized Controlled Trial." BMC Complementary and Alternative Medicine, vol. 11, 2011, p. 15.
Matsumoto K, Yamada H, Takuma N, et al. Effects of green tea catechins and theanine on preventing influenza infection among healthcare workers: a randomized controlled trial. BMC Complement Altern Med. 2011;11:15.
Matsumoto, K., Yamada, H., Takuma, N., Niino, H., & Sagesaka, Y. M. (2011). Effects of green tea catechins and theanine on preventing influenza infection among healthcare workers: a randomized controlled trial. BMC Complementary and Alternative Medicine, 11, p. 15. doi:10.1186/1472-6882-11-15.
Matsumoto K, et al. Effects of Green Tea Catechins and Theanine On Preventing Influenza Infection Among Healthcare Workers: a Randomized Controlled Trial. BMC Complement Altern Med. 2011 Feb 21;11:15. PubMed PMID: 21338496.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Effects of green tea catechins and theanine on preventing influenza infection among healthcare workers: a randomized controlled trial. AU - Matsumoto,Keiji, AU - Yamada,Hiroshi, AU - Takuma,Norikata, AU - Niino,Hitoshi, AU - Sagesaka,Yuko M, Y1 - 2011/02/21/ PY - 2010/10/13/received PY - 2011/02/21/accepted PY - 2011/2/23/entrez PY - 2011/2/23/pubmed PY - 2011/7/27/medline SP - 15 EP - 15 JF - BMC complementary and alternative medicine JO - BMC Complement Altern Med VL - 11 N2 - BACKGROUND: Experimental 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. INTERVENTIONS: The catechin/theanine group received capsules including green tea catechins (378 mg/day) and theanine (210 mg/day). The control group received placebo. MAIN OUTCOME MEASURES: The 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. RESULTS: Eligible 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). CONCLUSIONS: Among healthcare workers for the elderly, taking green tea catechins and theanine may be effective prophylaxis for influenza infection. TRIAL REGISTRATION: ClinicalTrials (NCT): NCT01008020. SN - 1472-6882 UR - https://www.unboundmedicine.com/medline/citation/21338496/Effects_of_green_tea_catechins_and_theanine_on_preventing_influenza_infection_among_healthcare_workers:_a_randomized_controlled_trial_ L2 - https://bmccomplementalternmed.biomedcentral.com/articles/10.1186/1472-6882-11-15 DB - PRIME DP - Unbound Medicine ER -