The “Founding Congress of the Tea Industry and Health Branch of the Chinese Health Care Association and High-Quality Development Seminar for the Healthy Tea Industry” was recently held in Beijing. Experts and scholars from the tea industry conducted in-depth discussions on Tea drinking and health, as well as the development of the tea industry. At the conference, the President and Secretary-General of the “Tea Industry and Health Branch of the Chinese Health Care Association” were announced, with Zhao Yihong, Chairman of Biopharm Holdings Co., Ltd., and Yu Hongjiang, Executive Vice President, assuming these roles respectively. Professor He Jiguo, Head of the Department of Nutrition and Food Safety at the College of Food Science and Nutritional Engineering, China Agricultural University, analyzed the transition from eating tea to drinking it, and from Drinking Tea to appreciating it based on various sources. He believes that the role of tea in human health cannot be overlooked.
The fresh leaves of tea contain substances such as tea polyphenols, proteins, alkaloids, and amino acids. Tea polyphenols have antioxidant properties. Extensive animal studies have reported that catechins, a component of tea polyphenols, exhibit cancer-preventing and anti-cancer effects against tumors induced by chemical carcinogens in organs such as the skin, lungs, esophagus, stomach, liver, and oral cavity. Furthermore, the combination of polysaccharides from black fungus and tea polyphenols has positive implications in fighting atherosclerosis.
In reality, tea polyphenols can impact every stage of the formation and progression of atherosclerosis, primarily through inhibiting the oxidation of cholesterol in low-density lipoproteins (LDL) mediated by Cu2+ ions, endothelial cells, and macrophages, thereby delaying the onset of atherosclerosis. The potential mechanisms include scavenging free radicals such as superoxide anions, hydroxyl radicals, and lipid peroxides, interrupting chain reactions; chelating and removing iron and copper ions; inhibiting the production and release of hydrogen peroxide by macrophages; protecting α-tocopherol in lipoproteins and promoting its regeneration; inhibiting various enzymes including cyclooxygenase, lipoxygenase, and superoxide dismutase; and suppressing inflammatory responses.
Experiments have shown that tea polyphenols in tea are mainly responsible for combating atherosclerosis. Long-term consumption of tea does not delay the development of atherosclerosis by lowering plasma fat levels but rather through the antioxidant activity of tea polyphenols. 57BL/6J mice lacking apurinic/apyrimidinic endonuclease (APE1) are susceptible to atherosclerosis. They were fed a high-fat diet along with Green Tea extracts or a placebo. It was found that tea intake did not affect the plasma concentrations of cholesterol and triglycerides in the mice, but the concentration of lipid peroxides in the plasma of the tea-drinking group was reduced, and the area of atherosclerosis from the aortic arch to the muscular artery bifurcation was decreased. Additionally, the weight of the aorta was 23% less than in the control group, and the contents of cholesterol and triglycerides in the aorta were reduced by 27% and 50%, respectively. Although animal experiments have demonstrated that tea can reduce high plasma cholesterol levels and hypertension, in strictly controlled human trials, it does not lower blood pressure or lipids. Green tea extracts can delay peroxidation reactions in copper-catalyzed LDL oxidation experiments in vitro, scavenge free radicals, and inhibit the spread of lipid peroxide groups. Among them, tea polyphenols have the strongest effect, Theanine is slightly weaker, and the effect of theobromine is very limited. Therefore, the inhibition of lipid peroxidation activity by green tea extracts is primarily due to tea polyphenols.
In summary, tea polyphenols impact every stage of the formation and progression of atherosclerosis, primarily by inhibiting cell-mediated LDL oxidation and thus delaying the onset of atherosclerosis. Currently, there is limited in vivo experimental data regarding the absorption, metabolism, and excretion of tea polyphenols. Their physiological functions, especially their effects on the structural cells of the arterial wall and inflammatory cells in vivo, as well as their synergistic effects with other antioxidants in food such as vitamin C, vitamin E, carotenoids, and arachidonic acid, remain unclear. Similar components to tea polyphenols are also present in other functional foods, which requires further research.
Figure: Professor He Jiguo, China Agricultural University