Iced black tea can help gastrointestinal digestion, remove greasy, stimulate appetite, promote health, increase appetite, diuresis and eliminate edema. Black tea can enhance heart function. Black tea is mild in nature and mellow in aroma, which helps to strengthen bones first. Secondly, drinking black tea can prevent and treat influenza, myocardial infarction, stroke and skin diseases. Studies have found that frequent mouthwashing with black tea or direct drinking can prevent influenza; Black tea is rich in trace element potassium. After brewing, 70% potassium can be dissolved in tea, which can enhance blood circulation of the heart and reduce calcium consumption in the body. People who drink five cups of black tea a day have a lower risk of stroke than those who don't drink black tea. It is best to drink black tea with milk. People who drink tea without milk have a relatively high proportion of oxalic acid in their bodies. Generally, oxalic acid can be excreted with urine, but for some people, some oxalic acid will still accumulate in the body and eventually form kidney calculi. Calcium in milk can be combined with oxalic acid, which can be eliminated smoothly. It is recommended to drink black tea at night. Because green tea belongs to non-fermented tea, it has high content of tea polyphenols, maintains its original properties and is irritating; Black tea is a completely fermented tea. Although the content of tea polyphenols is low, it is mild after "aging" and suitable for drinking at night. Especially for people with weak spleen and stomach, adding some milk when drinking black tea can play a certain role in warming the stomach. However, people who are easily excited or sensitive, have poor sleep and are weak should drink less or not drink tea at night. In addition, when drinking tea at night, you should put less tea leaves and don't make the tea too strong. It is best to drink tea after meals, because drinking tea on an empty stomach will harm your health, especially for people who don't drink tea often, it will inhibit the secretion of gastric juice, hinder digestion, and seriously cause palpitations, headaches and other "tea drunk" phenomena. Black tea is not suitable for cold drinks, which affects the effect of warming the stomach. If it is left for too long, it will reduce the nutrients.