Green tea consists of an ingredient , which may help kill oral cancer cells, without touching the healthy cells, says a new research.

Associate professor Joshua Lambert at Penn State said that earlier studies had shown that epigallocatechin-3-gallate-EGCG-a compound found in green tea, killed oral cancer cells without harming normal cells, but researchers did not understand the reasons for its ability to target the cancer cells. The current study shows that EGCG may trigger a process in the mitochondria that leads to cell death.

The researchers studied normal human oral cells side-by-side with human oral cancer cells to determine how EGCG was affecting cancer cells differently than normal cells.

They grew the normal and cancer cells on petri dishes and then exposed them to EGCG, the major polyphenol found in green tea, at concentrations typically found in the saliva after chewing green-tea chewing gum. At various times, the researchers would collect the cells and check for oxidative stress and signs of antioxidant response.

The researchers said that a protein called sirtuin 3 -- SIRT3 -- was critical to the process, so the idea that EGCG might selectively affect the activity of sirtuin 3 in cancer cells-to turn it off-and in normal cells-to turn it on-was probably applicable in multiple kinds of cancers, Lambert said.

The study builds on earlier research on how EGCG affected oral cancer, a disease that is expected to kill more than 8,000 people in the United States this year.

He said the next step would be to study the mechanism in animals. If those tests and human trials are successful, the researchers then hope to create anti-cancer treatments that are as effective as current treatments without the harmful side effects.

Lambert said chemotherapy drugs just targeted rapidly dividing cells, so cancer divides rapidly, but so did the cells in your hair follicles and cells in your intestines, leading to a lot of side effects. But green tea consumption didn't have such side effects.

The study is published in the online issue of Molecular Nutrition and Food Research.