Sugar is one of the important substances for human survival. Sugar is one of the three nutrients and the main source of heat energy. The heat energy provided by sugar accounts for about 60 ~ 70% of the total heat energy needed by human body. Except cellulose, all sugars are sources of heat energy. Sugar is the most abundant organic compound in nature. Sugar mainly exists in cereals, cereals, potatoes, beans, rice flour products, vegetables and fruits in various forms of starch, sugar and cellulose. It accounts for about 80% of its dry matter in plants, and the sugar in animal food is very small, accounting for about 2% of its dry matter. Eating too much sweets is easy to get various diseases. Some experts believe that sugar is more harmful to human body than cigarettes and alcoholic beverages. The World Health Organization has investigated the causes of death in 23 countries, and concluded that sugar addiction is more harmful than smoking, and long-term consumption of foods with high sugar content will shorten people's life span by 20 years. Therefore, in 1995, the World Health Organization put forward a new slogan of "global sugar ban". A survey by the World Health Organization found that eating too much sugar can lead to heart disease, hypertension, arteriosclerosis, cerebral hemorrhage and diabetes. Long-term high-sugar diet will make the internal environment of human body unbalanced, and then cause various hazards to human health. Because sugar is an acidic substance, eating too much sugar will change the pH of human blood, present an acidic constitution, weaken the resistance of human white blood cells to external viruses, and make people susceptible to various diseases. People who love sweets for a long time are likely to cause a variety of eye diseases. Experts also suggested that senile cataracts are also related to excessive sweets. They investigated 50 cataract patients and found that 34% of them have the habit of eating sweets, which they think is related to the disorder of glucose metabolism. Eating too much sugar affects children's height. Eating too much sugar will affect the consumption of body fat and cause fat accumulation. Eating too much sugar can also affect calcium metabolism. Some scholars believe that if the sugar consumption reaches 16- 18% of the total food consumption, the calcium metabolism in the body will be disordered and the calcification in the body will be hindered. A survey in Japan shows that the fracture rate of children has increased, and they think that too much sugar is an important cause of fracture. Eating too much sugar will make people feel full and have poor appetite, which will affect food intake and lead to various nutrient deficiencies. Children's long-term high-sugar diet directly affects the growth and development of children's bones, leading to rickets. If children eat too much sugar and don't pay attention to oral hygiene, it provides good conditions for the growth and reproduction of oral bacteria, which is easy to cause dental caries and oral ulcers. In order to avoid diseases such as dental caries, myopia, rickets and digestive tract, the World Health Organization appeals to parents not to let their children eat too many sweets. Moderate consumption will not affect health. In recent years, due to more and more articles on the harm of sugar to human health, some one-sided publicity and public opinion have made people worry about eating sugar, which makes them feel terrible. The conclusion of the sugar research task force of the US Food and Drug Administration is that sugar can cause other diseases besides dental caries, which is unfounded. As a part of a reasonable diet, eating sugar is the same as eating other things. As long as it is eaten in moderation, it will not be harmful to the body.