Written by Jianping Liu, Xun Li and the CAM-Cancer Consortium.
Updated February 13, 2014

Green tea (Camellia sinensis)

Does it work?


A total of 27 systematic reviews and/or meta-analyses of epidemiological studies investigated associations between green tea consumption and the risk of developing cancer. Details of the included reviews are presented in Table 1. None of studies detected an increased risk for any cancer.

Cancer in general 

Three recent systematic reviews 4 6 7 and a 2009 Cochrane review 25 concluded that there is insufficient and conflicting evidence to establish an association between green tea consumption and incidence of cancer. In general, inverse associations for green tea consumption and risk of gastrointestinal tract, oesophageal (women), lung (non-smoking women), ovarian, prostate and breast cancer were found. Evidence for a protective role of tea intake on the development of cancers of liver, colorectum, pancreas, urinary tract, prostate, glioma, lymphoma, and leukaemia was, however, insufficient. 

Lung cancer 

A 2009 meta-analysis of 12 studies indicated a borderline significant association between highest green tea consumption and reduced risk of lung cancer, and an increase in green tea consumption of two cups/day was associated with an 18% decreased risk of developing lung cancer.8 A newly published systematic review only included 5 human-related studies, and found insufficient evidence to support green tea use for preventing lung cancer.9 Another meta-analysis of 6 cohort/case control studies published in 2012 found significant nonlinear dose-response relationship between green tea consumption and risk of lung cancer, showing favourable effect of green tea consumption especially when the dose was more than 7 cups per day.10 

Esophageal cancer 

None of the three systematic reviews/meta-analyses published in 2012 11 and 2013 12 13 found a significant association between high/medium/low dose versus non/least of green tea consumption and cancer risk in overall population, but there seems to be reduced cancer risk with green tea consumption among female 11 12 and in the Chinese 13 population. 

Stomach cancer 

According to the latest systematic review (2013) including 7 cohort and 10 case control studies, 14 the association between green tea consumption and stomach cancer remains conflicting since the publication of the two meta-analysis in 2010 15 and 2009 16 and warmer tea seems to be associated with lower cancer risk. One systematic review based on a Japanese population published in 2012 found a consistent risk reduction of stomach cancer with green tea consumption in women only based on prospective data, whilst the inverse association among the general population was consistent according to retrospective studies. 17 

Liver cancer 

A meta-analysis of 13 studies published in 2011 found an inverse association with a borderline significance between tea consumption and primary liver cancer in both men and women. Green tea consumption was associated with a moderate reduction in risk (RR=0.79; 95% CI=0.68-0.93) for primary liver cancer.18 19 

Colorectal cancer 

A 2006 meta-analysis of 8 studies indicated a reduced risk of colorectal cancer with green tea consumption from combined results.19 The inverse association was observed only in case-control studies. Two systematic reviews published in 2012 both found reduced cancer risk in higher dose green tea consumption. 20 21 Inverse association of cancer risk and green tea consumption seems to focus in Asian population including Shanghai and Singapore people. 

Bladder cancer 

Among the three newly conducted meta-analyses,22 23 24 only one 22 (including one cohort and nine case control studies of different types of tea, two cohort and two case control studies of green tea) found protective effects on bladder cancer when pooling the data for green tea consumption only. 

Prostate cancer 

A systematic review published in 2009 found conflicting results for an association between green tea consumption and prostate cancer,6 while a later meta-analysis of seven studies published in 2011 indicated that consumption of green tea may have a protective effect on prostate cancer in Asian populations, especially in Chinese people.25 

Breast cancer 

A 2010 meta-analysis of nine studies found that increased green tea consumption (more than 3 cups a day) was inversely associated with breast cancer recurrence in the analysis of case-control studies but not in the cohort studies.26 An updated meta-analysis published in 2013 found no significant association among cohort nor case control studies, however, a linear but not significant dose-response association was detected.27 

Ovarian cancer 

Three systematic reviews found uniformly inverse association between green tea consumption and ovarian cancer risk.28 29 30

Citation Jianping Liu, Xun Li , CAM-Cancer Consortium. Green tea (Camellia sinensis) [online document]. http://ws.cam-cancer.org/The-Summaries/Herbal-products/Green-tea-Camellia-sinensis. February 13, 2014.


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