Green Tea May Reduce Risk of Colorectal and Stomach-Esophageal Cancer

Article by Arnie Gitomer

Long term consumption of green tea could help to slash the risk of gastrointestinal cancers by over a quarter, according to new research in Chinese women

Prospective cohort study of tea consumption and risk of digestive system cancers: results from the Shanghai Women's Health Study, by Nechuta S, Shu XO, Li HL, Yang G, Ji BT, Xiang YB, Cai H, Chow WH, Gao YT, Zheng W.

Division of Epidemiology, Department of Medicine, Vanderbilt University School of Medicine, Nashville, TN.

Background:
Data from in vitro and animal studies support a protective role for tea in the etiology of digestive system cancers; however, results from prospective cohort studies have been inconsistent. In addition, to our knowledge, no study has investigated the association of tea consumption with the incidence of all digestive system cancers in Chinese women.

Objective:
We investigated the association of regular tea intake (=3 times/wk for >6 mo) with risk of digestive system cancers.

Design:
We used the Shanghai Women's Health Study, a population-based prospective cohort study of middle-aged and older Chinese women who were recruited in 1996-2000. Adjusted HRs and associated 95% CIs were derived from Cox regression models.

Results:
After a mean follow-up of 11 y, 1255 digestive system cancers occurred (stomach, esophagus, colorectal, liver, pancreas, and gallbladder/bile duct cancers) in 69,310 nonsmoking and non-alcohol-drinking women. In comparison with women who never drank tea, regular tea intake (mostly green tea) was associated with reduced risk of all digestive system cancers combined (HR: 0.86; 95% CI: 0.74, 0.98), and the reduction in risk increased as the amount and years of tea consumption increased (P-trend = 0.01 and P-trend < 0.01, respectively). For example, women who consumed =150 g tea/mo (~2-3 cups/d) had a 21% reduced risk of digestive system cancers combined (HR: 0.79; 95% CI: 0.63, 0.99). The inverse association was found primarily for colorectal and stomach/esophageal cancers.

Conclusion:
In this large prospective cohort study, tea consumption was associated with reduced risk of colorectal and stomach/esophageal cancers in Chinese women.

Am J Clin Nutr. 2012 Nov;96(5):1056-63. doi: 10.3945/ajcn.111.031419. Epub 2012 Oct 10
PMID: 23053557 [PubMed - in process] PMCID: PMC3471195 [Available on 2013/11/1]

The study adds to the list of potential health benefits of green tea and the compounds it contains.

The majority of science on tea has looked at green tea, with benefits reported for reducing the risk of Alzheimer's and certain cancers, improving cardiovascular and oral health, and helping with weight management.

Green tea contains between 30 and 40% of water-extractable polyphenols, while black tea (green tea that has been oxidized by fermentation) contains between 3% and 10%. Oolong tea is semi-fermented tea and is somewhere between green and black tea.

The four primary polyphenols found in fresh tealeaves are epigallocatechin gallate (EGCG), epigallocatechin (EGC), epicatechin gallate (ECG), and epicatechin (EC).