Subjects who drank green tea and avoided burning hot fluids had significantly lower cancer risk. Most researchers believe that it is the polyphenols in green tea that are responsible for the health benefits. More specifically, certain catechins found in tea are believed to be the most powerful. The catechins in green tea make up a large percentage of the total amount of polyphenols. While the level of polyphenols and catechins in green tea can vary, depending on growing conditions, quality of the leaf, and brewing methods, the following approximates the amount in a cup of green tea.
Further research is needed.