Table 1.

Preventive effects of tea and tea polyphenols against cancer and cardiovascular diseases in experimental animals and humans.

Disease	Preventive effects reported in laboratory animals	Preventive effects reported in human epidemiological or case-control studies
Skin cancer	Prevention of photocarcinogenesis (Mukhtar and Ahmad, 2000; Yang and Wang, 1993) Decrease in progression of papillomas to SCC (Katiyar et al., 1997) Reduction in tumor incidence or multiplicity and tumor growth (Nihal et al., 2005; Lu et al., 1997) Decrease in papilloma formation and size (Conney et al., 1999) Decrease in UVB-induced bifold-skin thickness, skin edema and infiltration of leukocytes, suppression of UV-induced MAPKs and NFκB (Afaq et al., 2003) Increase in the rate and extent of disappearance of the mutant p53-positive patches (Lu et al., 2005) Reduction in skin tumor incidence, tumor multiplicity, tumor growth, inhibition of MMPs, VEGF and PCNA, increase in CD(8+) T cells and caspase-3 activity (Mantena et al., 2005)	In a population-based case-control study, black tea intake was found to be associated with decreased risk of skin SCC (Hakim and Harris, 2001) Protective effect of tea on cutaneous malignant melanoma in a case-control study (Naldi et al., 2004)
Liver cancer	Decrease in GST positive hepatic foci (Xu et al., 1992; Zhong et al., 2001) Inhibition of hepatocarcinogenesis, reduction in tumor multiplicity and tumor incidence (Landau et al., 1998) Decrease in number and area of GST-P-positive foci, induction of p21, inhibition of cyclin D1 and cdk4 (Jia et al., 2002)	Inhibition of liver cancer by green tea (Sueoka et al., 2001) In a population based case-control study conducted in Taixing, Jiangsu province, green tea drinking decreased risk for the development of gastric cancer by 78% in alcoholics and by 48% among cigarette smokers (Mu et al., 2003).
Lung cancer	Reduction in tumor volume (Landau et al., 1998) Reduction in tumor incidence and multiplicity (Landau et al., 1998; Banerjee et al., 2005) Reduction in progression of adenoma to adenocarcinoma (Naldi et al., 2004)	In a case-control study in Uruguay, heavy drinkers of tea were associated with a reduced risk (Mendilaharsu et al., 1998) In a population-based case-control study in Shanghai, among nonsmoking women, green tea was associated with a decreased risk of lung cancer and the risks decreased with increased consumption (Zhong et al., 2001) In a case control study, a protective effect of frequent (daily or several times per week) black tea drinking against risk of lung cancer appeared among non-smoking women (Kubik et al., 2004)
Gastrointestinal tract cancer	Reduction in tumor incidence and multiplicity, inhibition of tumor promotion (Hiura et al., 1997; Takada et al., 2002; Qanungo et al., 2005) Inhibition of small intestinal tumorigenesis, increase in E-cadherin and decrease in nuclear beta-catenin, c-myc, phospho-Akt, and phospho-ERK1/2 in small intestinal tumors (Ju et al., 2005)	In a population based study in Japan, green tea decreased development of gastric cancer and esophageal cancer (Wang et al., 1999) Green tea caused reduction in risk for the development of stomach cancer by 81% in alcoholics and by 16% among cigarette smokers in a case control study in Taixing, China (Mu et al., 2003) In same study, there was decrease in esophageal cancer by 39% in alcoholics and by 31% among cigarette smokers (Mu et al., 2003)
Pancreatic and bladder cancer	Inhibition of pancreatic tumor initiation, hyperplasia and total duct lesion (Hirose et al., 1995) Decrease in the numbers of hyperplasia and total pancreatic duct lesions (Majima et al., 1998) Inhibition of formation of bladder tumors (Umemura et al., 2003)	In a large population-based case-control study conducted in Shanghai, China, decrease in pancreatic cancer with increasing amount of green tea consumption (Ji et al., 1997) Decrease in urinary bladder cancer (Lambert and Yang, 2003)
Breast cancer	Increase in mean latency of tumors (Li et al., 1999) Decrease in tumor incidence, multiplicity and tumor size (Suganuma et al., 2001) Reduction of tumor growth accompanied with increase in Bax/Bcl-2 ratio, reduction in PCNA and activation of caspase 3 (Baliga et al., 2005)	Increased consumption of green tea was closely associated with decreased numbers of axillary lymph node metastases in patients with stage I and II breast cancer (Nakachi et al., 2000) In a case control study, significant decrease in risk of breast cancer (Wu et al., 2003) In a population-based case-control study of breast cancer in Chinese, Japanese, and Filipino-American women in Los Angeles County, green tea drinkers showed a significantly reduced risk of breast cancer (Wu et al., 2003) In Japan, women consuming >10 cups of tea had lower risk for breast cancer metastasis and recurrence (Lambert and Yang, 2003) A meta-analysis examined populations in eight countries indicate a lower risk for breast cancer with green tea consumption (Sun et al., 2006)
Prostate cancer	Delay in primary tumor incidence and tumor burden, decrease in PCNA, inhibition of CaP development and increase in survival time (Gupta et al., 2001) Reduction in IGF-I and increase in IGFBP-3, inhibition of markers of angiogenesis and metastasis (Adhami et 2006) Decrease in tumor size (Kavanagh et al., 2001) Decrease in PSA secretion (Wang et al., 1999; Roomi et al., 2005) Inhibition of CaP development and metastasis (Mantena et al., 2005) Inhibition of CaP progression with reduction of S100A4 and restoration of E-cadherin (Saleem et al., 2005) Inhibition in growth of implanted level PSA, induction of apoptosis prostate tumors, reduction in the level of serum with upregulation in Bax and decrease in Bcl-2, decrease in VEGF (Siddiqui et al., 2006)	In a case-control study conducted in South-east China, prostate cancer risk declined with increasing frequency, duration and quantity of green tea consumed (Baliga et al., 2005) Chemopreventive effect of green tea in patients of HG-PIN in Italy (Bettuzzi et al., al., 2004, 2006)
Cardiovascular disease	Vasculoprotective, antioxidative, antithrombogenic, anti-inflammatory lipid-lowering effects (Wu et al., 2003) EGCG caused decrease in cholesterol in plasma, hepatic total cholesterol, triglyceride and cholesterol absorption and LDL cholesterol Increase in fat excretion and HDL cholesterol (Raederstroff et al., 2003) Green tea caused reduction in systolic and diastolic blood pressure, increase in catalase expression (aorta) Decrease in nitric oxide plasma concentration (Negishi et al., 2004) Green tea leaves in diet caused in reduction in blood triglycerides and total cholesterol contents (Stangl et al., 2006)	Consuming ≥ 10 cups/day of green tea is linked with decreased relative risk of death from CVD in men and women (Nakachi et al., 1998) In a case control study, 44% decrease in cardiovascular risk in the individuals drinking more than a cup of tea per day (Sesso et al., 1999) Inverse association between tea intake and coronary heart disease mortality (Nakachi et al., 2000) Decrease in aortic atherosclerosis in a cross sectional study of 512 coronary patients (Sasazuki et al., 2000) Decrease in rate of CVD with increased green tea consumption(Peters et al., 2001) Decrease in relative risk of death from CVD for people consuming over 10 cups of green tea a day (Sueoka et al., 2001) In a prospective cohort study, 31 and 39% reduction in cardiovascular risk in moderate and heavy tea drinkers (Mukamal et al., 2002) Inverse association of green tea intake and myocardial infarction (Hirano etal., 2002) Inverse association of green tea with atherosclerosis (Wu et al., 2003) Green tea Improves arterial compliance and endothelial function (Wu et al., 2003)