Systematic review: green tea and gastrointestinal cancer risk.
BACKGROUND
Gastrointestinal cancer is one of the leading causes of cancer mortality in the world. Therefore, numerous efforts are being made to find chemoprotective substances able to reduce its incidence. Amongst these, green tea, one of the most popular beverages world-wide, has been reported to provide protective effects against gastrointestinal cancer.


OBJECTIVE
To critically evaluate all epidemiological studies reporting an association between green tea consumption and a reduced risk of gastrointestinal cancer.


METHODS
Epidemiological studies of green tea consumption in relation to gastrointestinal cancer or preneoplastic lesions were identified through computerized literature searches using the following databases: Medline (Pubmed), Embase, Amed, CISCOM, Phytobase and Cochrane Library. Only epidemiological studies indicating the type of tea (green tea) and the site of either cancer or precancerous lesions (stomach or intestine) were included. No language restrictions were imposed.


RESULTS
Twenty-one epidemiological investigations met our inclusion/exclusion criteria.


CONCLUSIONS
These studies seemed to suggest a protective effect of green tea on adenomatous polyps and chronic atrophic gastritis formations. By contrast, there was no clear epidemiological evidence to support the suggestion that green tea plays a role in the prevention of stomach and intestinal cancer.
Borrelli
F
F
Department of Experimental Pharmacology, University of Naples Federico II, Naples, Italy. franborr@unina.it
Capasso
R
R
Russo
A
A
Ernst
E
E
D001628:Beverages; D003430:Cross-Sectional Studies; D005770:Gastrointestinal Neoplasms / Q000453:epidemiology / Q000517:prevention & control*; D011230:Precancerous Conditions; D012307:Risk Factors; D013662:Tea
D013662:Tea