There are now more active clinical trials using green tea against cancer than any other plant extract: twenty-two trials are currently running (fifteen are still recruiting). PubMed now lists nearly 1600 peer-reviewed research articles, which mention "green tea" and "cancer," and the list is growing at about 150 per year. Despite all this research, a clear-cut recommendation for green tea intake has been frustrated by several factors. Population studies have based their data on "cups per day" consumed, but the amount of cancer-fighting polyphenols per cup changes dramatically according to brewing time, amount used per cup, and type of tea (sencha, bancha, genmaicha etc.). Even the same tea will yield different EGCG contents according to time of harvest and position on the plant from which the leaves are harvested.