In research conducted at the Linus Pauling Institute at Oregon State University published in the February 2003 issue of the journal Carcinogenesis, it was found that both green tea and white tea reduced colon polyps as well as the nonsteroidal anti-inflammatory drug (NSAID) sulindac, and that a combination of sulindac and white tea reduced polyp formation even more. Previous research has shown that sulindac can cut polyp formation by one half. The research was funded by the National Cancer Institute.
In the Linus Pauling Institute study, mice bred to develop intestinal tumors were given drinking water to which was added green tea, white tea, sulindac, a combination of white tea and sulindac or plain water for twelve weeks. At the study's conclusion, the mice who received green tea had 17 tumors compared to 30 tumors in the control group. White tea further reduced polyp formation to 13, and a combination of the tea with sulindac resulted in a finding of only 6 polyps. Because NSAIDs such as sulindac can have side effects, an agent that increases the efficacy of a lower dose would be valuable.
Coauthor Gayle A Orner of Oregon State University wrote, "Tea is one of the most widely consumed beverages in the world, and recent upswings in the sales of green tea in the United States can be attributed to reports of potential health benefits against cancer and other chronic diseases. Teas exert significant protective effects in experimental animal models of skin, lung, esophageal, gastric, hepatic, small intestinal, pancreatic, colon, bladder and mammary cancer . . . These are pretty exciting results."
What's especially significant is that as far as we can tell consumption of tea has none of the side-effects of NSAIDs, which can be severe, including bleeding, ulcers and even death" Orner said.
Although the complications from prolonged use of NSAIDs can be significant, they often are dose-dependent, the researchers noted in their report. Any cancer preventive agent that worked effectively in combination with NSAIDs and allowed use of lower dosages could be quite significant, the scientists said, and green or white tea consumption may fit that description exactly. Tea and its constituents also have been found to have many additional cancer-preventive mechanisms in their own right, the report said. These include antioxidant properties, induction of cell-cycle arrest, inhibition of oncogene expression, apoptosis induction, and other factors. In-vitro studies, they said, have suggested that tea plus sulindac may work in synergy to kill human lung cancer cells.
The level of tea consumption in humans that might provide useful levels of polyphenols could be equated to drinking about three coffee-sized mugs a day, the scientists said. This is based on studies in Japan with green tea and gastric cancer, where researchers essentially concluded, "the more the better."
Orner GA, Dashwood WM, Blum CA, Diaz GD, Li Q, Dashwood RH. Suppression of tumorigenesis in the Apc(min) mouse: down-regulation of beta-catenin signaling by a combination of tea plus sulindac. Carcinogenesis. 2003 Feb;24(2):263-7.