Men who drink black tea in moderation for a long period of time generally have no harmful effects, and can supplement the body with minerals and other nutrients, but if you drink a lot of black tea for a long period of time, it may lead to intestinal discomfort and affect the quality of sleep. 100 grams of black tea contains 324 calories, of which 59.2 grams of carbohydrates, 26.7 grams of protein, 1.1 grams of fat, vitamin A645IU, vitamin C8 milligrams, 378 milligrams of calcium, 28.1 milligrams of iron. Black tea has a certain role in promoting appetite as well as helping gastrointestinal digestion, a small amount of black tea does not have much impact, but if you often drink too much black tea, due to the inclusion of a tannic acid substances, may have an adverse effect on the intestinal tract, resulting in intestinal discomfort. And black tea contains a lot of caffeine, excessive intake will excite the nervous system, if too much black tea before going to bed at night will easily affect sleep, and even lead to insomnia or aggravate insomnia. It is recommended to drink black tea in moderation, avoid drinking too much black tea for a long time.