Tea, both green tea and black tea, is a common beverage drunk across the world. It is currently being studied as a way to prevent cancer. Black tea involves about 75 percent of tea consumed; however, green tea is more of a cancer preventative than black tea.
One article (1) discussed tea and its ability to prevent cancer. It noted that it’s the polyphenols in tea such as EGC, EGCG, ECG, and EC that are the ingredients in tea that fight cancer. They have antioxidant properties, meaning that they scavenge for oxygen free radicals that can cause cancer by damaging the DNA inside cells.
These components of tea also seem to block the proliferation of cancer cells and can cause programmed cell death in cancer cells. This is also known as apoptosis. The ingredients in tea also stop new blood vessel growth in cancerous areas of the body. This means that, not only does tea prevent cancer, but it seems to treat cancer as well.
Source: 1.Tea and Cancer Prevention. https://www.cancer.gov/about-cancer/causes-prevention/risk/diet/tea-fact-sheet. Accessed 9/14/16.