Cancer prevention by green tea: evidence from epidemiologic studies

AJCN Nutrition. October 2013

Jian-Min Yuan

+ Author Affiliations

From the University of Pittsburgh Cancer Institute and Department of Epidemiology, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, PA.
+ Author Notes

Presented at the conference “Fifth International Scientific Symposium on Tea and Human Health,” held at the US Department of Agriculture, Washington, DC, 19 September 2012. The conference was organized by Jeffrey Blumberg, Tufts University, Boston, MA, and a Steering Committee including representatives from each of the symposium cosponsors: the American Cancer Society, the American College of Nutrition, the American Institute for Cancer Research, the American Medical Women's Association, the American Society for Nutrition, and the Linus Pauling Institute. The symposium was underwritten by the Tea Council of the USA. Its contents are solely the responsibility of the authors and do not necessarily represent the official views of the Tea Council of the USA or the cosponsoring organizations.

This work was partially supported by NIH grant R01CA144034.

Address correspondence to J-M Yuan, 5150 Centre Avenue, UPMC Cancer Pavilion Suite 4C, Pittsburgh, PA 15232. E-mail: Esta dirección de correo electrónico está protegida contra spambots. Usted necesita tener Javascript activado para poder verla..">Esta dirección de correo electrónico está protegida contra spambots. Usted necesita tener Javascript activado para poder verla..

Abstract

In contrast to the consistent results of an inhibitory effect of green tea extracts and tea polyphenols on the development and growth of carcinogen-induced tumors in experimental animal models, results from human studies are mixed. Both observational and intervention studies have provided evidence in support of a protective role of green tea intake in the development oral-digestive tract cancer or an inhibitory role of oral supplementation of green tea extract on a precancerous lesion of oral cavity. Evidence in support of green tea intake against the development of liver cancer risk is limited and inconsistent.

An inverse association between green tea intake and lung cancer risk has been observed among never smokers but not among smokers. Although observational studies do not support a beneficial role of tea intake against the development of prostate cancer, several phase 2 clinical trials have shown an inhibitory effect of green tea extract against the progression of prostate premalignant lesions to malignant tumors. Prospective epidemiologic studies so far have not provided evidence for a protective effect of green tea consumption on breast cancer development. Current data neither confirm nor refute a definitive cancer-preventive role of green tea intake. Large randomized intervention trials on the efficacy of green tea polyphenols or extracts are required before a recommendation for green tea consumption for cancer prevention should be made.

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