Numerous epidemiologic studies suggest an inhibitory action of black tea against carcinogenesis. According to researcher, black tea's 'secret weapon' may be a compound called TF (theaflavins). The diverse inhibitory activities are also observed in different animals carcinogenesis systems and different cancer cell lines.

There are multiple potential mechanisms by which theaflavins elicit their inhibitory effects against carcinogenesis:

• Antioxidative effects
• Antimutagenic effects
• Anti-proliferation effects
• Inhibition of cell growth and apoptosis-inducing activity
• Inhibition tumor promotion-related enzymes
• Modulation of signal transduction pathways