High consumption of green tea, say 10+ cups per day, may be associated with decreased risk of gastric cancer. Black tea has been shown to be unrelated to not only gastric cancer but other cancers. Black tea may be less biologically active than green tea; black tea is a fermented product, and tea catechins are polymerized. Green tea extract inhibits the occurrence of chemically induced gastric adenocarcinoma (Cancer 1996; 77: 1662-7). Tea polyphenols are shown to be inhibitory against tumor formation and growth (JNCI 1993; 85: 1038-49).