Childhood is vigorous, lively and active, the muscle system develops very fast, and the demand for heat energy and protein is very high. Children's growth and development alternate. Generally, it remains relatively stable after 2 years old, with an annual growth of 4-5 cm in height and 1.5-2.0kg in weight. When girls reach the age of 10 and boys reach the age of 12, their growth and development suddenly increase. The annual growth rate of height is 3% ~ 5%, and the annual growth rate of weight is 10% ~ 14%, with an annual increase of 4 ~ 5 kg, and some cases reach 8 ~ 10 kg. About three years later, the growth rate slowed down again. Therefore, school-age children are at the peak of growth and development in the later period, so the demand for various nutrients is greatly increased. In the process of growth and development, the development of each system is unbalanced, but unified and coordinated. For example, the weight of the brain at birth is 25% of that of adults, and it has reached 1 200g at the age of 6, which is 90% of that of adults. After that, although it only increased by 65,438+00%, the structure and function of brain cells have entered a complex mature process. The reproductive system hardly developed before 10, but it began to develop rapidly after 10. Therefore, the growth and development of each system are mutually influenced and adapted. Any factor acting on the body can affect many systems, such as proper physical exercise, which can not only promote the development of muscle and bone system, but also promote the development of respiratory system, cardiovascular system and nervous system. The material basis of growth and development is various nutrients. Good quality and adequate nutrition are the basic guarantee for children's physical and mental development. (1) Heat energy: The World Health Organization recommends that the heat energy supply standard for children aged 4- 12 is 1830-2470 kcal. If calculated by weight, the daily heat supply of children aged 4-6 per kilogram of body weight is 9 1 kcal; 7 ~ 9 years old 78 calories; 10 ~ 12 years old 66 kcal. That is to say, with the increase of age, their calorie demand for weight will be relatively reduced. The Nutrition Society of China suggested that the thermal energy supply for children should be 7 ~ 10 years old 1 800 ~ 2 100 kcal, 10 ~ 13 years old and 2,300 kcal. (2) protein: protein is the basic component of tissues and cells, and its requirement is closely related to the amino acid composition of food protein. School-age children are in a period of vigorous growth and development, and they need protein most. The demand for various amino acids calculated by unit weight is higher than that of adults. For example, the essential amino acids for adults are 100,/kloc-0 ~12 years old children are 330 valine, 320 leucine, 300 isoleucine, 500 threonine, 200 phenylalanine plus tyrosine and 6544 tryptophan. It can be seen that children's demand for essential amino acids is many times that of adults. Among them, lysine has a direct effect on growth and development. Japan tried fortified lysine bread. One year later, the average height of the experimental group who ate fortified lysine bread was 5.7 cm higher than that of the control group who did not eat it. This kind of bread has been tried in Wuhan, Guangxi and other places in China, and has also received good results. While supplying proper amount of essential amino acids, we should also supply enough non-essential amino acids to synthesize protein. The World Health Organization suggested that protein quality, that is, amino acid score or chemical score, should be used to determine the requirement of protein. Higher quality protein, such as animal protein and soybean protein, needs less daily. The daily protein of children aged 4 ~ 12 is 0.84 ~1.01g. The supply of protein can be different according to the nutritional value of protein, for example, when the net utilization rate of protein is 60%, it is 34 grams for 4-6 years old; For 7-9 years old, it is 465,438+0g. If the net utilization rate of protein is 80%, the protein requirement of 4-6 years old is 26g, and that of 7-9 years old is 31g. The demand of protein is closely related to the intake of heat energy. The supply of heat energy must meet the needs of children, otherwise the dietary protein will not be able to play its special physiological functions. Therefore, protein often accounts for a certain proportion of heat energy supply. Protein supply of children aged 3 ~ 12 in China accounts for 12% ~ 14% of thermal energy, that is, 50 g ~ 55 g for children aged 5 ~ 6, 60 g ~ 70 g for children aged 7 ~ 10, and 10 ~. (3) Minerals and trace elements: Growing children need a lot of minerals needed for protein synthesis and bone growth, such as calcium and phosphorus, which are necessary for the development and calcification of bones and teeth. In addition, trace elements such as iron, iodine, zinc, copper, chromium and fluorine are also closely related to growth and development. For example, iron deficiency can cause malnutrition anemia, so we should pay special attention to it. ① Calcium and phosphorus. China Nutrition Society suggested that the daily calcium supply for children aged 6 ~ 10 was 800 mg, and that for children aged 10 ~ 12 was 1000 mg. There is less milk in our diet, and calcium mainly comes from vegetables and bean products. Because phytic acid, oxalic acid, cellulose and pectin in vegetables have certain influence on calcium absorption, the supply should be slightly increased. The content of phosphorus in our diet is generally not lacking. Bone meal and fish meal are ideal sources of calcium and phosphorus, which are not only suitable in proportion, but also easy to be absorbed and utilized. If there are symptoms of rickets, it should be treated in time, and calcium and vitamin D preparations should be given when necessary. ② Iron. School-age children grow vigorously, their hematopoietic function is greatly enhanced, and their need for iron is higher than that of adults. The Nutrition Society of China recommended that the iron supply for children aged 6 ~ 12 should be 10 ~ 12 mg per day. If you don't get enough food, you can supplement it with iron-containing fortified foods or iron preparations to meet your physiological needs. ③ Zinc. According to domestic investigation, zinc deficiency is very common among children in China. Children aged 4 ~ 6 need 6 ~ 10 mg, 7 ~10mg and 7 ~15mg of zinc at birth. Children aged 7 ~ 12 can be used as a reference for making recipes or dietary supply. Generally speaking, grains and vegetables contain more phytic acid, oxalic acid and cellulose, which will affect the absorption of zinc, so it is best to choose seafood or meat, viscera and other foods rich in zinc. ④ Other trace elements. Children's iodine deficiency growth and intellectual development will be affected, so they should eat more seafood such as kelp; Iodized salt should be supplied in iodine-deficient areas. In addition, cobalt, copper, magnesium, selenium and fluorine are all essential trace elements for children and are generally not lacking. But in some areas, some special diseases are caused by the lack of some trace elements in soil and water, so we should pay attention to prevention. (4) Vitamins: ① Vitamin A. There are not many foods with high vitamin A such as milk, eggs and liver in children's diets in China. It is mainly supplied by carotene in various vegetables. However, the utilization rate of carotene in the body is poor. Children over 5 years old should eat more foods with high vitamin A content, such as cream and animal liver, or take oral vitamin A preparations, and the daily dosage is 2000 ~ 4000 international units. 2 vitamin D. Although the skeletal development of school-age children is slower than that of infants, if vitamin D is lacking, advanced rickets can still occur. Foods containing vitamin D are limited, and the content cannot meet the needs of children's growth and development. Cod liver oil or other vitamin D preparations should be given. Generally, you should consume 300 ~ 400 international units or get more sunshine every day. 3 Vitamin C. Different countries in the world have different views on the supply of vitamin C. China stipulates that 3 ~ 12 years old, every 2 ~ 3 years old is an age group, and the supply of vitamin C is 40, 45 and 50 mg respectively. Higher than foreign standards, the loss of food in the cooking process has been taken into account, and the intake is slightly higher, which is helpful to strengthen health and improve the body's resistance to diseases. ④B vitamins. The requirement of B vitamins is directly proportional to the thermal energy, that is, vitamin B 10.6 mg, vitamin B20.5 mg and nicotinic acid 6 mg should be supplied for every calorie intake of 1000. Thiamine and nicotinic acid are generally not lacking in our diet, but if we take white rice or flour and corn as the staple food and can't supplement appropriate non-staple food, we may have symptoms of deficiency. The demand for riboflavin can't be met, so we should try to choose viscera such as animal liver and kidney, eggs, bean paste, tofu, peanuts, sesame paste and fresh green leafy vegetables to improve the supply. According to the research, the requirement of vitamin A has a certain relationship with everyone's weight, physiological condition and occupational nature. Generally speaking, the minimum physiological requirement of vitamin A is 2000 international units (600 micrograms of retinol equivalent) per day, and the safe intake is 3500 international units (1050 micrograms of retinol equivalent). So β -carotene is calculated as 3.6 mg and 6.3 mg respectively. Some people think that at least 20 ~ 50 international units (6 ~ 15 microgram retinol equivalent) are needed per kilogram of body weight every day. Vitamin (vitamin food) A In order to obtain the maximum antioxidant protection, the recommended daily optimal nutrient intake of vitamin A and β -carotene is: 800- 1000 μ g retinol equivalent for children (food for children) and 800-2000 μ g retinol equivalent for adults. You can take 2,000 micrograms (6,600 international units) to 3,000 micrograms (/10 000 international units) of retinol and beta-carotene every day. The recommended optimal daily intake of vitamin C is 150mg for children and 400- 1000mg for adults. For maximum antioxidant protection, you can take 1000-3000 mg every day. The recommended optimal daily intake of vitamin E is 70 mg for children and 90-800 mg/international unit for adults. For maximum antioxidant protection, you can take 400-800 mg/IU daily. The recommended optimal daily intake of selenium is 50 micrograms for children and 0/00 micrograms for adults. For maximum antioxidant protection, you can take 100-200 micrograms every day. The recommended daily intake of zinc is 7 mg for children and 15-20 mg for adults. For maximum antioxidant protection, you can take10-20mg every day.