An American study has found that theaflavin-2 - a substance found only in black and oolong teas - was able to induce aptosis (cell death) in cancer cells in the laboratory within three hours of treatment. The theaflavin-2 acted by activating a specific set of genes that kill cancer cells and by reducing cell inflammation.(http://www.ncbi.nlm.nih.gov/pubmed/20669245)