The Role of Nutrition in Supporting the Growth and Development of Children and Adolescents

Childhood and adolescence are, in terms of growth and development, an important and irreversible period. Proper nutrition in this period provides the person with the opportunity for optimal development, makes possible their optimal physical and mental growth, and, most importantly, instills a correct dietary pattern in them for almost their entire life. Children who have been well nourished and cared for have enough energy to respond to and learn from the stimuli around them and establish a better relationship with their surrounding environment, parents, and close ones. Nutrition from birth to 6 months of age Among the characteristics of infancy are physical growth and neural and psychological development. Newborns who are born on time (after 37 weeks) weigh on average 3000 to 3300 grams. In the first 3 to 4 days of life, due to loss of body water, the newborn's weight decreases by about 200 to 300 grams, but after that, in the first three months of life, about 1 kilogram per month, and in the second three months about half a kilogram per month, is added to the infant's weight. In other words, the weight of a newborn born on time will be double its birth weight at four to five months of age. As the child's age increases, its growth rate also decreases. The height of a normal newborn at birth is about 50 centimeters, which in the first six months of life increases on average by about 3 centimeters per month. Mother's milk alone can supply all of a child's nutritional needs until the end of 6 months of age. Therefore all infants up to six months of age must be fed exclusively with mother's milk so that they have optimal growth, development, and health, and those infants who are fed exclusively with mother's milk do not need water even in hot weather. Of course, the use of drops, syrups containing vitamins, and permitted medicines is allowed. Nutrition at ages 6 to 12 months The main characteristic of growth in this period of life is greater growth of the chest circumference at 6 to 9 months and greater growth of the body's limbs at 9 to 12 months. This is while in the first six months of life, the growth of the head is greater. If the infant's weight at the end of 6 months is within the normal range and the infant does not face a problem of slow growth, the infant will gain on average 330 grams per month between 6 and 9 months, and 250 grams per month from 9 to 12 months. Likewise, the height of a normal newborn, which is about 50 centimeters at birth, must reach about 75 centimeters at the end of 12 months. After the end of 6 months of age, the child's nutritional need is not supplied by mother's milk alone, and it is necessary that, in addition to mother's milk, complementary food also be given to the child. Of course, mother's milk still supplies a major part of the infant's needs, and the infant must be fed with mother's milk at least 8 times in a day and night. In fact, from 6 to 12 months, mother's milk is still the infant's main food, and complementary foods along with mother's milk play a significant role in preparing for and completing the child's psychological and social development. Nutrition at ages 1 to 2 years The rate of growth after the first year of life decreases noticeably, such that although at the end of 1 year of age the child's weight has become 3 times its birth weight, at the end of the second year of life the child's weight will not even reach four times its weight at birth. The growth rate of height in this period also decreases compared to the first year of life, such that compared to the first year of life, in which about 25 centimeters is added to the height at birth, the growth in height in the second year is about 12.5 centimeters. Given the importance of continuing breastfeeding at these ages, about 30 percent of the infant's daily energy needs at these ages will be supplied through mother's milk. And the remainder must be supplied through the foods the infant consumes, which will gradually become similar to family-table foods. Unlike the first year of life, at these ages it is better for breastfeeding to be done half an hour to 1 hour after the child eats food, and in fact feeding from the family table takes priority over breastfeeding with mother's milk. Most mothers are worried about the inadequacy of the food their child receives at these ages. It must be explained to these mothers that the child's growth and development and the optimal increase in the child's weight and height are the best criteria for assuring the adequacy of the infant's nutrition, and if the infant's monthly growth is sufficient, they should not worry about the inadequacy of the infant's nutrition. Nutrition at ages 2 to 5 years The growth rate at these ages has noticeably decreased compared to the early years of life, such that the amount of monthly weight gain in healthy children at these ages is about 200 grams per month, and the amount of height increase at ages 24 to 36 months is about 9 centimeters, and after that about 7 centimeters per year until age 5, such that the height of children at the end of 5 years of age (60 months) will reach about 110 centimeters. To supply the energy and all the nutrients needed, the diet of these children must include a combination of various foods made up of the main food groups. The main food groups are: 1/ The bread and grains group (including bread, rice, and pasta), which supplies the energy, B-group vitamins, iron, fiber, and protein the child needs, and which must take up the largest share of the child's daily food. 2/ The vegetables and fruits group, which supplies the vitamins, minerals, and fiber the child needs, and plays a role in increasing the body's resistance against diseases. 3/ The milk and dairy group (including milk, yogurt, cheese, kashk, and ice cream), which supplies calcium, phosphorus, protein, B-group vitamins, and vitamins A and D. 4/ The meat and substitutes group (including various meats, eggs, legumes, and nuts), which supplies the protein, iron, and zinc the child needs. The last food group is fats and sugars, which must take up a very small share of the diet. Only in children who do not gain weight well can butter or vegetable oils be used to enrich the food. In children who have an optimal growth rate, excessive use of fats can be accompanied by an increased risk of obesity. The appropriate diet for children at these ages must contain daily 6 units of bread and grains, 5 units of the fruits and vegetables group (preferably 3 units of vegetables and 2 units of fruit), 2 units of the milk and dairy group, and 2 units of the meat and substitutes group. The size of the share of each food group, broken down for ages 24 to 36 months and 36 to 59 months, is explained in a table. Nutrition at school ages (6 to 18 years) Proper nutrition at school ages is of special importance because of its role in physical and mental growth and academic progress. For example, about 25 to 30% of an adult person's height is achieved at these ages. Given that the age of puberty also falls within this period of life, attention to the correct lifestyle of students in general and to their dietary pattern in particular is of greater importance. In addition, lifestyle and eating habits of people also take shape in this period, and thus the lifestyle and dietary pattern of adolescents at these ages can play a significant role in the prevention and control of non-communicable diseases in later years of life. On the other hand, this period is also accompanied by numerous challenges. Students spend part of their daily time outside the home and increasingly resort to consuming between-meal snacks. Their susceptibility to influence from friends and the surrounding environment can also lead to some changes in their behavioral patterns, including dietary behaviors. Despite the very great importance of this period in growth and development and also the shaping of eating habits, there are numerous problems in the nutrition of this age group, among which one can mention not eating breakfast, consuming high-energy foods poor in some nutrients, unbalanced intake of food groups and subsequently a deficiency in the intake of calcium, iron, and some vitamins, and also excess weight and obesity. The weight of boys in this period increases up to age 10 by about 2 kilograms per year from 10 to 17 years of age by about 4 kilograms per year from 17 to 20 years of age by about 1 to 2 kilograms per year. In the case of optimal weight gain, after age 20 the weight must be kept constant. The weight of girls from 7 to 14 years of age increases by about 4 kilograms per year from 14 to 17 years of age by about 2 kilograms per year. In the case of optimal weight gain, after age 18 the weight must be kept constant. In boys, the height growth spurt is at ages between 13 and 16. In girls, the height growth spurt is at ages 10 to 13. In boys, height up to age 13 increases by 5 centimeters per year from 13 to 15 years of age by 8 centimeters per year from 15 to 17 years of age by 4 centimeters per year from 17 to 19 years of age by 2 centimeters per year, increasing, and after that height growth stops. In girls, height up to age 13 increases by 6 centimeters per year from 13 to 18 years of age by 1 to 3 centimeters per year, increasing, and after that height growth stops. Nutritional needs at these ages depend on the person's weight, height, and level of physical activity. Consuming 3 to 4 units of dairy, consuming at least 5 units of fruit and vegetables, and also consuming 120 to 170 grams daily from the meat and substitutes group are required for optimal growth at these ages.