<prompt> tafadhali geuza maudhui haya ya swahili kwenda kwa kiingereza.chai ya kijani inajulikana sana nchini amerika kama chanzo tajiri cha polyphenols, ambayo inaweza kupunguza hatari ya saratani.  <response>: green tea is widely known in the united states as a rich source of polyphenols, which are antioxidant chemicals that can reduce the risk of cancer. 