A study published earlier this week concluded that compounds present in green tea can help prevent dementia like Alzheimer's and can help fight cancer by slowing down the growth of tumor cells. It was already known that these nutrients existed in green tea, but it has been proven conclusively that the body does in fact absorb them during the digestion process.
Polyphenols, a type of chemical found in green tea, bind with toxic chemicals to protect brain cells. When digested, these chemicals have been shown to slow down the growth of cancer cells.
You can read more about this study in this article.