he debate brewing over the benefits of green tea heated up Tuesday with the release of new research supporting the cancer-fighting properties of the earthy beverage.
Four research papers presented at the American Association for Cancer Research conference in Phoenix suggest green tea is useful in fighting certain types of cancer, in addition to lowering cholesterol, preventing heart disease, boosting oral hygiene and possibly aiding in weight loss.
Drinking just two cups, but probably more like four cups, a day of green tea may retard the growth of certain tumor cells, researchers agreed.
Iman Hakim, a researcher at the University of Arizona Cancer Center, showed that cigarette smokers who drank four cups a day of decaffeinated green tea for four months cut the cellular damage caused by cigarettes.
“What we found was significant,” she said, referring to tests done on the urine of the 118 smokers in the study.
The research stopped short of finding that genes damaged from smoking can be repaired by green tea. That is the subject of new research her colleagues are now doing.
Other research presented Tuesday by Jia-Sheng Wang, from Texas Tech University, showed green tea can prevent liver cancer, the third-leading cause of cancer deaths in the world. And Nurulain Zaveri, a researcher at SRI International in Menlo Park, California, found that green tea may not only prevent cancer but may become a treatment for those with the disease.
But researchers reminded cancer patients to consult with their doctors before consuming large quantities of the tea because it could interact with other treatments or chemotherapy.
“If you like it, you (probably) can continue to drink it,” said Chung Shu Yang, chair of the chemical biology department at Rutgers University, which has been studying the therapeutic effects of green tea for a dozen years.
Green tea has been shown to be effective against lung, prostate, liver and esophageal cancer, among others.
“So, the biology actually is there and that’s very exciting,” Yang said. “But the disappointing part is we really don’t know how it works.”
Yang said anyone who drinks hot beverages, green tea included, should avoid drinking them too hot because of the association with oral and esophageal cancers.
Earlier in the day, other researchers at the high level and internationally recognized scientific conference presented the benefits of ginger extract and a traditional Chinese herb, both of which may stop the growth of cancer cells. More mainstream findings about diet, exercise and the effect of aspirin use on women and pancreatic cancer have been presented over the past three days. The conference ends Thursday.
The ginger finding came from a study of mice. Those fed 500 micrograms of gingerol (the source of ginger’s spiciness) three times a week for two weeks developed fewer tumors after being injected with human colorectal carcinoma cells. Mice fed gingerol also survived longer, implying that the tumors grew slower, said Ann Bode, at the Hormel Institute at the University of Minnesota.
“The mice were a good (model) for human tumor development because they had no immune system,” Bode said, adding that they were more susceptible for developing cancer once they were implanted with human colon cancer cells.
But fed gingerol, the mice developed a “marked suppression” of cancer cells, leading researchers to conclude the extract fueled apoptosis, or cell death, or interfered with a cellular transcription process.
“It’s likely that it’s inducing cell death,” she said.
Ginger has been used since antiquity for preventing digestive problems, nausea, sea sickness and motion sickness. It also has shown to work against skin, ovarian, colon and breast cancer tumors. But it has not been scientifically tested for halting the progression of colon cancer, until now.
Meanwhile, researchers found that the Chinese herb “Scutellaria Barbata” was found to slow the progression of prostate tumors, also in mice. The herb is related to mint of the Labiate family.
The work was done at Union College in Nebraska by Brian Wong, lead author of the study, and other researchers. Wong said he hopes to apply the findings to humans.
The herb has long been part of Chinese medicine, used by doctors to treat everything from hepatitis to appendicitis to snake bites and lung and rectal cancer. Wong said his mother forced him to drink the bitter dark tea as a child whenever he got sick.
He and other researchers explored whether the herb could stop cell growth in prostate cancer, the second most commonly diagnosed cancer in men. They experimented with mice, feeding them “SB,” as it is known and discovered that 50 to 70 percent of those given moderate to high doses were cancer free at the end.
Wong said translated to humans, they would need to drink a few ounces but not daily because it contains toxins that can be damaging.
– As reported by Kerry Fehr-Snyder
The Arizona Republic
October 29, 2003