Nutrition for Infants, Children, and AdolescentsEach child is an unique individual whose heredity and environment shape the course of his or her life. Woven into the daily life are aspects of food and nutrition. What childhood memories of food do you have? Are these memories healthy or unhealthy? Foods and their nutrients are essential to life. In the beginning years of life an infant’s nutritional health depends on the family unit. Parents must have knowledge of the changing food needs of the child and must also have sufficient resources to provide food, shelter, and clothing for the family.
Equally important, parents create the cultural and psychological environment that influences the development of food habits, setting the patterns for later years. During the preschool years some children depend solely on family caregivers for their nutritional needs. For other preschooler children the responsibility for meeting nutritional needs is shared by the family and others, such as caregivers in child-care centers and babysitters.
The child entering school becomes influenced by teachers and peers, and learns to broaden his or her experiences with food. For many people, the adolescent years often are turbulent as the teenager seeks independence and freedom from adult rules and standards. In this research, I will focus on nutrition, in retrospect to growth and development in infants, preschoolers, school children and adolescents. Infants vary widely in their growth patterns, so it would be unwise to compare one infant with another. Yet there is value in being familiar with typical patterns of growth and development. At birth, the fetus makes an abrupt transition to life outside the uterus.
Adaptation to extrauterine life is one of the most important steps in the life cycle because, for many systems in the body, birth precipitates dramatic changes in function. The respiratory system undergoes major changes as the newborn’s lungs fill with air during the first breath, and gas exchange across the pulmonary circulation abruptly replaces placental transfer. Similarly, birth triggers a major transformation in nutritional pathways and metabolism of the newborn. At a time when nutritional needs are high (per unit body weight higher than at any other time after birth) the newborn must abruptly begin to swallow, digest, and absorb a variety of complex proteins, lipids, and carbohydrates. No longer are readily available simple substrates provided by the mother via the placenta.
The newborn begins to convert substrates-protein to glucose, glucose to fat, and must adapt to a discontinuous supply of nutrients. Glycogen stored during feedings must be converted to glucose to support energy needs between feedings. Adding further to the vulnerability of the newborn period, many of the digestive and absorptive functions of the newborn are incompletely developed (Schmitz, 1991).To ease the transition through this turbulent period, the newborn needs to be provided with easily digestible and bioavailable nutrition in the form of breast milk or infant formula. The infant depends on a diet of closely regulated composition and does not achieve nutritional independence until weaning. Here I will focus on the physical growth during infancy.
Physical growth is more rapid during the first few months postpartum than at any other time after birth. In the first three months, a healthy infant’s birth length increases by 20% and, by the end of the first year, by 50%. By the end of infancy (2 year old) the average child has already achieved half the ultimate adult height. Although the rate of growth is remarkably high during infancy, it is actually decelerating from the extremely high rates achieved during growth in utero. ( ) A healthy infant gains about 25 cm during the first year, but growth rate slows during the second year.
From age 1 to 2 years the average age height increases is 1-13cm. As the newborn adjusts to life outside to uterus, changes in physiology produce losses of body water and small amounts of body tissues. Also, in the first few days after birth, the energy supplied by breast milk does not yet meet the needs of the newborn. As a result, the infant loses about 6% of birthweight in the first few days after birth. By the end of the first week the infant begins to gain weight rapidly and, by about the tenth day, has regained birthweight. By the age 4 months, most infants have doubled their birthweights, and by the end of the first year, birthweight has tripled.
Although the rate of weight gain during infancy is high, it decelerates from a peak rate obtained in the utero. From birth to age 4 months the infant gains 20-25 each day, and from 4 months to 1 year, weight gain slows to 15g per day. It would be interesting to note that a series of growth charts have been developed for normal ranges of weight, length, and head circumference. With these charts, parents and the pediatric health care team can plot an infant’s measurements and growth progress compared with infants of the same gender and age. If the infants moves along a given percentile rating, individual progress is likely to be satisfactory for that infant-although short deviation into another percentile channel usually is not important. However, an infant who dramatically or steadily moves into a different channel, either higher or lower, and remains there, prompts identification of the cause.
For example, if the infant suddenly drops into a lower channel, eating problems, negative environmental situations, or perhaps an illness that is interfering with growth, should be explored. Dramatic changes in body composition occur during early infancy. As the infant grows and gains weight, all three major body compartments-water, fat, and lean tissue increase in size. However, proportions between the major compartments change. At birth about 75 percent of the infant’s weight is water and 12-15 percent is fat. The relatively high amount of water, low amount of subcutaneous fat, and the proportionately large surface area explain why precautions must be taken to keep the infant well hydrated and warm. Each infant requires a certain amount of vitamins, minerals, proteins, water, energy, carbohydrates, and fats to meet its nutritional and developmental needs.
The Recommended Dietary Allowances (RDAs) for the first six months are set at the level that a healthy, well-nourished infant would receive from breast-feeding. For the second six months, the levels of nutrients are based on satisfactory growth on a formula plus solid foods. Here I will outline these nutritional needs. Energy Needs- the actual energy requirement of individual infants will vary based on body size, level of activity, and rate of growth. These are important aspects.
Different infants have widely different activity patterns, some are restful and quiet while others spend more time crying, kicking, and moving. To support the remarkable growth however, a substantial portion of energy intake goes toward deposition of new tissue. The importance of high energy density diets are important, to meet high energy needs. Protein Needs- protein requirements per kilogram of body weight are higher during infancy than at any other time in life. Protein provides amino acids and energy for the formation of new muscle, connective tissue, and bone, as well as for synthesis of a large number of enzymes, hormones, and plasma protein.
The reference protein used for early infancy is human milk protein, and the protein requirement for the first few months after birth is based on the intake of protein by healthy breast-fed infants who are growing normally (NAS 1989). Amino Acid Needs- the nine amino acids that are essential for adults are also essential for infants. Several amino acids are considered conditionally essential.
Requirements must be at least partially met by dietary sources. For example cysteine is an essential amino acid during early infancy, because the synthetic enzymes that convert methionine to cysteine are not fully developed. Carnitine, also an amino acid, plays a central role in the metabolism of fat, is supplied in ample amounts in human milk and cow’s milk-based formulas but lacking in soy- based formulas.
Fat Requirements- infants require calorically dense foods to meet the high energy needs of growth. Human milk contains 50-55% of energy as fat, and most formulas contain 45-50% of energy as fat. Infants thrive and grow normally when fed diets with 30-60% of calories as fat; less energy-dense diets may result in inadequate energy intake. Water Requirements- infants needs for water per unit of body weight are significantly high, and the risk of dehydration is sharply increased during this period. There are several reasons for this.
Because infants have a larger surface area per unit of body weight, insensible losses from the skin and lungs are increased. Urinary and fecal losses also occur, and water is lost in growth, as it is incorporated into growing cells and tissues. Vitamin and Mineral Needs-all infants should receive vitamins. (fat soluble/water soluble vitamin) Vitamin A, D, E, & K plays key roles in growth, cellular differentiation, and immune system integrity during infancy. Vitamin C, B6, Folate, B12, & Thiamin, also contributes greatly for optimal infant growth.
Too much vitamins can be harmful to infants and small children resulting in diseases affecting that of which is susceptible. Iron is the element requiring special attention during the first year. Full-term infants are born with adequate iron stores for the first to six months. Human milk is low is in iron but 50 percent of the iron in breast milk is absorbed-it is highly bioavailable.
Human milk or formulas supply the recommended allowances for calcium, phosphorus, magnesium, and other minerals. “Breast feeding is best” is a teaching slogan used by health care providers. Some cultures expect new mothers to breast-feed and actively support their efforts, however, others do not. Each mother’s decision whether to breast-feed is a personal one, determined by a number of individual, family, and sociocultural factors. Breast feeding is a form of feeding where the child, through the mothers breast receives sufficient energy and nutrients which helps with growth and development of the infant. There are some advantages of breast feeding. Human milk is free of contamination by disease producing organisms, is instantly available at the right temperature for the infant, is nutritionally correct for healthy infants, and is usually less costly to produce even though the mother requires additional foods to support lactation. Breast-feeding provides benefits beyond optimal nutrition.
Human milk contains a complex variety of anti-infective substances and cells that reduce infections of the gastrointestinal tract and infant diarrheal disease. Also, breast feeding appears to be protective against food allergies. Formula feeding is another form of feeding in which it provides sufficient nutrition for optimal growth and development. Breast milk is the preferred food during early infancy, although current commercially prepared infant formula are adequate alternatives for mother who choose not to breast feed. Formulas are available in several forms and concentrations: single strength, ready to feed, in quart cans, or 4 oz or 8 oz disposable ready to feed bottles; concentrated liquid, which is measured into sterilized bottles and diluted with boiled or clean tap water; and powdered formula, to be diluted with water or added to other formulations as a nutrient/energy booster.
At this age, solid foods are introduced because the infant has better control of the tongue movements and swallowing mechanisms for handling solid foods. Moreover, there is less likelihood of allergic reactions to food. Solid foods also play a key role in supplying nutrients. However, infants like adults, happily respond to sweet foods. Too much sugar, could displace needed foods supplying proteins, vitamins, and minerals. It can upset water balance (osmotic balance) in the intestines and lead to diarrhea.
During these years, children’s growth patterns vary widely. Some children by heredity, are destined to be short and stocky, others tall and slender. Some children have growth spurts at an earlier age than others. As with infants, satisfactory progress is best determined by following the child’s own measurements from month to month, year to year. During the second year, the toddler’s weight gain is about 3.5-4.
5 kg (8-10lb). From the second birthday to the ninth year, the increase in height and weight is at a much slower rate. For instance, the annual gain in weight drops to 2-3 kg. Many physical and behavioral changes set the stage for maturation in the nutritional area. At this stage, children have lost most of their “baby fat.” The next years show muscles increasing in size and firmness, and bones becoming stronger.
Just the same for infants, preschool and school age children need the necessary nutrients to assist in the steady growth and development through the life stages. During these years, nutrient requirements vary from child to child, depending on individual variability. Interestingly, based on body weight, nutrient requirements of children are higher than those of adults. This is accounted mainly because of growth-children are in a state of positive nitrogen balance. Building good food habits and introducing new foods to children requires perseverance, as the appetites of young children are unpredictable, and their food likes and dislikes change quickly. However, preschool children will usually eat, enjoy, and develop preference for what is served to them regularly. By 4 or 5 years of age, most children have established a wide range of food preferences and aversions (Hammer 1992). Food preferences and habits are shaped by what type of food the child is offered, how it is offered, and parental and peer attitudes toward foods (Birch, 1987).
Young children prefer plain, simply flavored foods that are only lightly seasoned. Mixtures, as in casseroles, are well accepted as the children older. Foods requiring chewing are essential for oral development of strong bones, teeth, and mouth muscles.
These body structures are crucial for proper speech development. Foods too tough for primary teeth to chew, like meats, are better chopped for the preschool child and for the child whose secondary teeth are erupting. Vegetables are typically the least preferred food group.Children sometimes go on food jags. They will eat only certain foods, for instance, peanut butter and jelly sandwiches. Usually these diversions of appetite do not last too long if the parents make no particular point of them. If milk is refused as a beverage, it can be served as cooked cereals or puddings insuring that the child gets its correct and sufficient nutrients. Often it will be accepted again if it is poured into a decorated mug, or occasionally is flavored, or is colored with bright fruit purees or juices.
Plain yogurt and mild cheeses are good substitutes. A child, during this stage may have developed new food likes, but may face other problems related to maintaining good nutrition. Mornings in many homes are too often rushed, so that breakfast is a hurried meal or may be skipped entirely and a child who is apprehensive about school may eat poorly at lunch. Most children grow up healthy and well nourished. But along the path of childhood, some children fail to achieve their full potential because of inappropriate food habits, and inadequate supply of certain nutrients, and/or unhealthy environment. Food asphyxiation can be fatal, lead poisoning can be harmful, obesity occurs, and hyperactivity can result. …….A third and final period of rapid growth and metabolism occurs during this stage.
At this stage, teenagers have many interest in their physical and emotional development. For example, important topics are the size and shape of their bodies; their complexion, their overall appearance; and physical activity. Girls express a particular need for a good figure, healthy skin, and beautiful hair.
Boys are more likely to be interested in tall stature, muscular development, and athletic vigor and stamina. The RDA’s for adolescents are somewhat higher than those for adults men and women, with corresponding higher allowances for most vitamins and minerals. These increases are to satisfy the increased nutrient needs caused by their adolescent growth spurt. Bibliography: