Black tea theaflavins induce programmed cell death in cultured human stomach cancer cells.

The exposure of human stomach cancer KATO III cells to black tea theaflavin extract, free theaflavin, and theaflavin digallate that are main components of the extract, led to both growth inhibition and the induction of programmed cell death (apoptosis). Morphological changes showing apoptotic bodies were observed in the cells treated with black tea theaflavin extract, theaflavin and theaflavin digallate. The fragmentations by these theaflavin compounds of DNA to oligonucleosomal-sized fragments that are characteristics of apoptosis were observed to be concentration- and time-dependent. These data suggest that drinking of black tea in large amounts is recommended to protect humans from stomach cancer.