Genes and Environment
Online ISSN : 1880-7062
Print ISSN : 1880-7046
REVIEW
The Past and Future of Studies on Tea and Cancer Prevention
Yoshiyuki Nakamura
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JOURNAL FREE ACCESS

2010 Volume 32 Issue 4 Pages 67-74

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Abstract

Tea (Camellia sinensis, Theaceae) is the most popular beverage in the world. Tea preparations are classified into four types: green, black, oolong and pu-erh teas. The cancer-preventive effects of tea extracts and tea polyphenols have been demonstrated in various experimental systems of mutagenesis and carcinogenesis. Anticarcinogenic effects of tea polyphenols have been reported in the tissues/organs of skin, esophagus, stomach, colon, bladder, lung, liver, pancreas, prostate, and mammary glands of various animal models. These effects are believed to be based on green tea catechins and black tea theaflavins. Polyphenols play potential roles in reducing oxidative stress, modifying carcinogen metabolism, enhancing DNA damage repair, inhibiting tumor promotion and metastasis, and/or modulating cell-cycle arrest, apoptotic death of pre-cancerous/cancerous cells, and oncogenic signal transduction. Indeed, much evidence on the cancer preventive effects of tea polyphenols has been reported in in vitro and animal experiments. However there is insufficient and inconsistent evidence for the association between tea consumption and cancer incidence or mortality in humans. This review includes perspective on: 1) antimutagenic and anticarcinogenic effects in in vitro systems; 2) anticarcinogenic effects in animal models; 3) molecular mechanisms of anticarcinogenesis; 4) biotransformation and pharmacokinetics of tea catechin; 5) epidemiological studies; and 6) possibilities of human cancer prevention by tea polyphenols and future problems for clarification.

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© 2010 by The Japanese Environmental Mutagen Society
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