Tea does not have a stomach, because tea with water can only be used as a drink, moderate drinking has the effect of refreshing the brain. Tea contains tea polyphenols, plant alkaloids, lipopolysaccharides, sugars, enzymes, proteins, amino acids, vitamins, pectins, organic acids, pigments and other organic chemical components. Tea has a refreshing effect, because the caffeine and other substances in tea can stimulate the central nervous system, thereby enhancing the excitability of the cerebral cortex. At the same time, tea is usually brewed with water and can be quickly rehydrated. Because the caffeine and other ingredients in tea can excite the central nervous system, insomnia people or should not drink before bedtime. Drinking tea cannot nourish the stomach. And tea can stimulate gastric acid secretion, easy to aggravate stomach upset, gastrointestinal ulcer crowd should not drink too much. Pregnant and lactating women should also control their intake.