In the United States, in 2003, tea polyphenols were listed as the best-selling dietary supplements; in 2006, tea polyphenols became the first Chinese herbal medicine approved by the US FDA;
In 2007, the US Department of Agriculture research report pointed out that the main reason for the health benefits of drinking green tea is that it contains tea polyphenols, especially EGCG. The activity of EGCG to quench free radicals is 100 times higher than vitamin C and 25 times higher than vitamin E.

Researchers from the University of Kansas in the United States and Showa University in Japan almost simultaneously reported that catechins in tea can alleviate the resistance of human pathogens to antibiotics. Experiments conducted in the United States with Staphylococcus aureus show that the development of drug resistance is related to the damage of bacterial cell DNA, and catechins have a strong antioxidant effect, which can inhibit DNA chain damage, thereby alleviating drug resistance. The role of. Clinical trials have proved that the use of catechins and tetracycline together can alleviate the development of drug resistance. Showa University in Japan used dimethicillin and Staphylococcus aureus as experimental materials, and the results showed that low-dose catechins can reverse the resistance of pathogenic bacteria. The mechanism is that catechins interfere with the integrity of the cell wall by directly binding to peptidoglycans on the cell wall, so that antibiotics can be enhanced by β-lactam. Since both catechin and β-lactam act on the same position of peptidoglycan on the cell wall, the effect is obvious.
 According to a recent study in the United States, fatty acid synthase (FAS) is an important therapeutic target for obesity. Green tea extract can effectively inhibit FAS activity, and its 50% inhibition concentration is 12.2 mμg dry weight/ml. The study found that: (-) catechin gallate (CG) is a strong inhibitor of FAS, and its 50% inhibitory concentration is 1.5 mμg/ml. (-) The inhibitory mechanism of CG is not due to its combination with β-ketoacyl reductase, while EGCG and ECG are mainly combined with β-ketoacyl reductase. According to the study of inhibition kinetics, lipid acyltransferase may be the main site of (-)CG reaction, and the B ring, C ring and gallate ring of (-)-CG are necessary to exert the inhibitory effect. The inhibitory effect of green tea extract on FAS mainly depends on the effect of polyphenol components.
 At the same time, studies have shown that the anti-cancer activity of tea is related to the activity of a transferase in the human body. According to an epidemiological survey of breast cancer and tea drinking conducted by the University of Southern California in 589 Asian American women, the results show that there is a significant negative correlation between tea drinking and breast cancer. Women who drink more tea have breast cancer. The incidence is low. Further research has found that tea polyphenols containing catechol are rapidly methylated and degraded in the human body due to the action of catechol-O-methyltransferase (COMT). According to a further study of 589 Asian American women with breast cancer and 563 control Asian American women, it was found that those with at least one low-activity catechol-O-methyltransferase allele, tea polyphenols The protective effect on breast cancer is obvious. For those tea drinkers with high activity of catechol-O-methyltransferase, because catechin compounds are rapidly degraded before they play a role, the anti-cancer activity is not obvious, and the occurrence of breast cancer in tea drinkers is related to There was no significant difference among non-tea drinkers. Therefore, the activity of catechol-O-methyltransferase in the human body is closely related to the anticancer activity.