Green Tea Consumption and Liver Disease

Xi Jin; Ruo-heng Zheng; You-ming Li


Liver International. 2008;28(7):990-996. 

In This Article


The search strategy comprised a search of Medline, Embase databases and Chinese databases including Chinese biomedicine web database and Chinese scientific journals' database using search terms 'green tea', 'liver', 'hepato', 'hepatic' and related Chinese translation, from 1989 to December 2007. Furthermore, citations from retrieved articles were also screened and no language restrictions were imposed. Study eligibility was assessed by two investigators (Xi Jin and Ruo-heng Zheng) independently and disagreements were resolved by consensus. The inclusion criteria for the studies were: (i) the study should have an interventional or an observational design; (ii) the focus of interest should be on green tea or its main ingredient (tea polyphenol, catechin); and (iii) the outcomes should be major liver diseases including liver disorders, hepatic cirrhosis, hepatocellular carcinoma, fatty liver disease and so on.

The characteristics abstracted from the articles included the first author's name, year of publication, study design, source of subjects, follow-up, response rate, country where this study was carried out, sample size, type of liver disease, potential confounders and bias in the analysis, outcome measurement, green tea dosage and duration, dose-response effect and research funding. Data from all articles were retrieved by Xi Jin and You-ming Li independently while the methods and results sections were cut out and coded to make the assessors blind to this information. Primary investigators were contacted if data were incomplete.

Assessment of Methodological Quality and Statistics. The methodological quality of included studies was assessed using a validated quality checklist.[17] The maximum score on the list is 32 and a score of 12 (38%) or greater was considered to have acceptable quality.[18] The main outcome considered in this article was a relative risk (RR) or odds ratio (OR) with a 95% confidence interval between subjects with, or without, green tea consumption. Also, in some studies, the relative serum markers or ratios representing the relief of liver disease were also presented. In those enrolled studies, appropriate Student's t-test for numerical variable and X 2 test for categorical variable were applied, as assessed and integrated in the quality checklist. P<0.05 was defined as being statistically significant in all analyses.


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