The Japanese green tea has many health benefits. One of them is the effect to prevent cancer. In Japan, there are a number of regions where green tea is produced, one of which is Shizuoka prefecture. In this prefecture, people drink more green tea than other areas of Japan, and a research was carried out about the link between cancer and green tea.
The results show that the death rate caused by stomach cancer is much lower in Shizuoka than the other areas of Japan. When the rate of Japan’s average death rate by the cancer was set as 100, the death rate of the same cancer in Shizuoka was only 34 for men and 52 for women. Furthermore these results are backed up by the results of several experiments conducted at later times, where different types of foods were given to several mice including green tea. The mice that ate green tea developed less cancer than the others.
Through these researches and experiments, it is now widely recognized that green tea is effective in preventing cancer. Then, why is green tea good against cancer? The main natural element of the green tea is catechin. Catechin is the element of bitterness and contains a high amount of antioxidants. The antioxidants prevent the oxidization of the membrane and keeps the membrane in a good condition by building up strong walls against cancer.
Other elements of green tea that work well to prevent cancer are vitamins A, C, E. Vitamin C and E are already present in the tea from the beginning, but vitamin A is not in the tea as it is. However, once the tea is taken in the stomach, the carotene contained in green tea changes into vitamin A. All these vitamins work well just like catechin, that means they build up strong walls on the membrane and help prevent cancer.
Reference:
Epidemiological and Experimental Studies on the Antitumor Activity by Green Tea Extracts
https://www.jstage.jst.go.jp/article/eiyogakuzashi1941/47/2/47_2_93/_article
Book: 緑茶 食べる・飲む (Eat and Drink Green Tea), Kazutami Kuwano (1993)