Tea Against Cancer

Tea Against Cancer

Considerable research is being carried out on the role of tea drinking in preventing cancer. Out of twenty-five papers related to health presented at the best results, with Lung Ching preferred.

Stomach cancer, the number one cause of death in Japan, is at its lowest rate in Shizuoka prefecture along the coast southwest of Tokyo. One explanation is that Shizuoka is a tea-growing district and its inhabitants drink large amounts of green tea. This is the conclusion of Professor I. Oguni of Shizuoka University, who did a twelve-year study using government demographic figures.

The study polled people in cities with high and low mortality rates from gastric cancer. In the low mortality areas, it found that people drank tea often and drank it strong. In the high mortality spots they favored weak tea and drank it infrequently, according to research presented by Oguni and others from Hamamatsu College of Shizuoka University and Terumo Corporation, at the Hang Zhou Symposium.

Similar findings were reported from a survey in China's Sichuan province in 1986 and another in 1986-1989 in Jiangsu province. The incidence of stomach cancer was found to be remarkably lower in Sichuan areas of heavy tea drinking. Jucha county in Jiangsu, where mush tea is drunk, was found to have a lower incidence of liver cancer than Qidong county, where not so much tea is used.

Tea has some effect against cancer because it inhibits the formation or action of cancer-causing substances. Tea may block the action of nitrosamines which can cause cancer, said Dr. Han Chi, an associate professor at the Institute of Nutrition and Food Hygiene under the Chinese Academy of Preventative Medicine. In a test of 145 types of tea, she and her colleagues rated green tea highest, with a blocking rate of 90%. Brick, Jasmine, oolong, and black tea followed in that order. They found that one gram of tea had some effect, and that three to five grams (three grams is one teaspoon) completely blacked the synthesis of nitrosamines in the human body. But it is too early to draw any conclusions, Dr Han told the Beijing meeting.

Other research at Hamamatsu College found that green tea inhibits the action of MNNG (N-methyl-N1-nitro-N-nitrosoguanidine), a synthetic carcinogen. This substance decreased by 84 percent in the blood of mice drinking green tea and 82% with black tea. On mice fed Japanese green tea, induced malignant tumors did not develop as rapidly as in those not on tea, according to Oguni and other researchers at Shizuoka University's School of Pharmaceutical Science and the Hamamatsu College Department of Food Nutrition. Green tea also inhibits the action of aflatoxin, a powerful carcinogen produced by mold in stored crops such as grains and peanuts. This ability of tea to counteract this chemical has been demonstrated in several Chinese studies.

[ Top ]   [ Back to tea and your health ]