Polyphenols are members of the flavonoid family. They are catechins made of several ringlike structures. The polyphenols in green tea are recognized as anticarcinogenic, and this polyphenol content, along with the naturally occurring vitamin C, helps strengthen blood vessel walls. EGCG is a powerful antioxidant and has been found to be 20 times stronger than vitamin E in protecting brain lipids, which are very susceptible to oxidative stress. In animal studies with mice, ECG has been shown to reduce the rate of lung, skin, and stomach cancer.
Green tea is regarded as an antioxidant.
The polyphenols, especially EGCG, prevent free radical damage and have even been found to detoxify free radicals produced by the environmental toxin paraquat. As a whole, human studies indicate that consuming green tea can lower the rate of esophageal cancer, mouth cancers, and gastric cancers. Recent research indicates that green tea may reduce the risk of some forms of stomach cancer. Surveys of Japanese tea drinkers show that those who consume four to six cups of green tea a day have lower levels of breast, esophageal, liver, lung, and skin cancers than those who consume less green tea or none at all. At a meeting of the American Chemical Society in 1991, researchers reported that even cigarette smokers who consumed green tea had a 45 percent lower risk of cancer than nontea drinkers.