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Meta-Analysis
. 2017 Dec;20(17):3183-3192.
doi: 10.1017/S1368980017002208. Epub 2017 Oct 5.

Association between green tea intake and risk of gastric cancer: a systematic review and dose-response meta-analysis of observational studies

Yanhong Huang  1 , Hongru Chen  1 , Liang Zhou  1 , Gaoming Li  1 , Dali Yi  1 , Yanqi Zhang  1 , Yazhou Wu  1 , Xiaoyu Liu  1 , Xiaojiao Wu  1 , Qiuyue Song  1 , Ling Liu  1 , Dong Yi  1
Affiliations
Meta-Analysis

Association between green tea intake and risk of gastric cancer: a systematic review and dose-response meta-analysis of observational studies

Yanhong Huang et al. Public Health Nutr. 2017 Dec.

Abstract

Objective: To examine and quantify the potential dose-response relationship between green tea intake and the risk of gastric cancer.

Design: We searched PubMed, EMBASE, Web of Science, CBM, CNKI and VIP up to December 2015 without language restrictions.

Setting: A systematic review and dose-response meta-analysis of observational studies.

Subjects: Five cohort studies and eight case-control studies.

Results: Compared with the lowest level of green tea intake, the pooled relative risk (95 % CI) of gastric cancer was 1·05 (0·90, 1·21, I 2=20·3 %) for the cohort studies and the pooled OR (95 % CI) was 0·84 (0·74, 0·95, I 2=48·3 %) for the case-control studies. The pooled relative risk of gastric cancer was 0·79 (0·63, 0·97, I 2=63·8 %) for intake of 6 cups green tea/d, 0·59 (0·42, 0·82, I 2=1·0 %) for 25 years of green tea intake and 7·60 (1·67, 34·60, I 2=86·5 %) for drinking very hot green tea.

Conclusions: Drinking green tea has a certain preventive effect on reducing the risk of gastric cancer, particularly for long-term and high-dose consumption. Drinking too high-temperature green tea may increase the risk of gastric cancer, but it is still unclear whether high-temperature green tea is a risk factor for gastric cancer. Further studies should be performed to obtain more detailed results, including other gastric cancer risk factors such as smoking and alcohol consumption and the dose of the effective components in green tea, to provide more reliable evidence-based medical references for the relationship between green tea and gastric cancer.

Keywords: Dose–response; Gastric cancer; Green tea; Meta-analysis.

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Figures

Fig. 1
Fig. 1
Flow diagram of the literature search and selection of studies for the current meta-analysis on green tea intake and risk of gastric cancer
Fig. 2
Fig. 2
Meta-analysis of high v. low dose of green tea and risk of gastric cancer for cohort studies by using fixed-effects model (a) and random-effects model (b). The study-specific relative risk (RR) and 95 % CI are represented by the black dot and horizontal line, respectively; the area of the grey square is proportional to the specific-study weight to the overall meta-analysis. The centre of the open diamond and the dotted vertical line represent the pooled RR; the width of the diamond represents the pooled 95 % CI
Fig. 3
Fig. 3
Meta-analysis of high v. low dose of green tea and risk of gastric cancer for case–control studies by using fixed-effects model (a) and random-effects model (b). The study-specific OR and 95 % CI are represented by the black dot and horizontal line, respectively; the area of the grey square is proportional to the specific-study weight to the overall meta-analysis. The centre of the open diamond and the dotted vertical line represent the pooled OR; the width of the diamond represents the pooled 95 % CI
Fig. 4
Fig. 4
Non-linear dose–response relationship between dose (a), years (b) and temperature (c) of green tea intake and the risk of gastric cancer: formula image, best-fitting fractional polynomial; formula image, 95 % CI. For temperature of green tea intake, 0, 1, 2, 3 and 4 represent undrinkable, cool, warm, hot and very hot, respectively
See this image and copyright information in PMC

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