The world is made of matter, so is the human body. The substances that make up the human body are: water, protein, lipids, carbohydrates, inorganic salts and vitamins.
In order to maintain life, engage in labor and reproduce, human beings must take food from outside. The whole process of human intake, digestion, absorption, metabolism and utilization of nutrients in food to meet their own physiological needs is called nutrition. The nutrients provided by food are called nutrients.
It has been found that the type and function of cells depend on the proper intake of nutrients. The interaction between nutrients and genes has a potential impact on human conception, growth, development, health and longevity, and may play a decisive role in the occurrence, development and prognosis of some diseases that lead to death. Therefore, nutrition is the material basis of life and survival, and people's birth and death are closely related to nutrition.
What nutrients do human health need? The nutritional function of food is realized by the nutrients it contains. These active ingredients are called nutrients. There are about 50 kinds of essential nutrients for human body, which are generally divided into 6 categories, including: protein, fat, carbohydrate (also called sugar), vitamins, minerals (including trace elements) and water. Among them, carbohydrate, fat and protein are called "three major nutrients" (now dietary fiber is called the seventh major nutrient).
Nutrients can be divided into macronutrients and micronutrients according to the requirements of human body. The former refers to nutrients, such as carbohydrate, fat, protein, water, potassium, sodium, calcium, magnesium, phosphorus, chlorine, etc., and the daily requirement is greater than1g. Micronutrients refer to nutrients with daily requirements ranging from a few grams to a few thousandths, such as iron, copper, zinc, chromium, manganese, molybdenum, selenium, iodine, fluorine and some vitamins.
Reasonable nutrition requires that food should contain all nutrients needed by human body, including protein, fat, carbohydrates, vitamins, inorganic salts, water and cellulose.
Food should have good color, fragrance and taste, which can stimulate appetite and be easily digested and absorbed.
This diet contains no harmful substances.
When the living and working environment and physiological conditions (such as pregnancy, lactation and menopause) change, the supply of dietary nutrition should also be adjusted accordingly.
Avoid insufficient or excessive nutrition supply.
The supply of nutrients is slightly higher than the body's demand for nutrients. The requirement of nutrients is the minimum basic amount necessary to maintain the normal physiological function of the body, and the supply is more sufficient than this.