Drinking coffee in moderation on a daily basis does not have much effect on the body, but drinking coffee in excess on a regular basis may cause some harm to the body. Coffee is a common beverage, which is made by roasting and grinding coffee beans. Coffee contains more substances, such as caffeine, nitrogen compounds, tannins and so on. Among them, caffeine is a kind of central nervous system stimulant, therefore, drinking coffee in moderation can refresh the mind and relieve fatigue. In addition, coffee also contains proteins, carbohydrates, minerals and other nutrients, often drink coffee in moderation to supplement the body’s nutrients, help maintain the normal physiological function of the body. Although coffee has many benefits, but because it contains caffeine on the central nervous system has a certain degree of stimulation, if a large number of long-term drinking, may appear headache and other symptoms. In addition, caffeine can also stimulate the gastrointestinal mucosa, promote gastric acid secretion, if you drink coffee on an empty stomach for a long period of time, it may aggravate stomach discomfort.