In the long river of history, the composition of diet is constantly changing, but its function remains unchanged, that is, to maintain people's life and health; Nutrition is the material basis of life. Nutrients make up thousands of kinds of foods, and all kinds of foods make up different styles of diets. Nutrition includes basic nutrition, human nutrition, medical nutrition, special nutrition and clinical nutrition. , which is closely related to food hygiene, is a science that studies the relationship between nutrients, food, diet, nutrition and human health. Scientific, social and applicable, closely related to the national economy and people's livelihood; It plays an important role in improving people's physique, preventing diseases and protecting and promoting health.

Section 1 A Brief History of Nutrition

The formation of nutrition and the development of related disciplines are closely related to the national economy and the level of science and technology. More than 2,000 years ago, China's "Huangdi Neijing" Su Wen put forward a dietary pattern of "five grains for nourishment, five fruits for help, five animals for benefit and five dishes for supplement". This is an ancient and simple nutrition theory summarized by our ancestors according to their own practical experience. It is still praised by nutritionists at home and abroad, and it is considered to be an ideal dietary model and should be popularized.

Modern nutrition originated at the end of18th century, and the whole19th century to the beginning of 20th century was the heyday of discovering and researching various nutrients. Basic nutrition focuses on studying the universal law between nutrition and human body from the perspective of biological science and basic medicine.

From the middle of19th century, after a long exploration, we gradually discovered and realized the physiological functions of nutrients, especially vitamins, except protein, fat, sugar (formerly known as carbohydrates) and minerals. The systematic study of trace elements began after 1930. At that time, regional diseases of people and animals with unknown causes appeared in some parts of the world, which were found to be related to trace elements through research and investigation. For example, 193 1 year, it is found that the mottled enamel teeth of people are related to the excessive fluorine content in drinking water; 1937 found that nutritional cartilage disorder in piglets was caused by manganese deficiency. From then on, the study of trace elements began. In the following 40 years, many trace elements, such as copper, selenium and zinc, have been discovered one after another and confirmed as essential trace elements for human body.