CHANGING REQUIREMENTS DURING DEVELOPMENT
Nutritional requirements change substantially in early childhood. The rate of physical growth in toddlers is lower than in infancy. This requirement goes up again during the pubertal growth spurt. Nutrient needs vary substantially according to the age, gender, and health status. Dietary reference intakes (DRIs) for various age ranges are outlined in Chapter 20, eTable 23.1.
Protein requirements are based on age and weight, with the requirement decreasing with age relative to weight but the total requirement increases with age. Additional factors, such as growth rate and state of health or illness, impact protein needs. It is important to recognize that recommended protein intakes assume high-quality protein providing amino acids essential to humans, such as eggs, milk, meat, poultry, and fish. If protein is primarily derived from lower-quality plant protein sources, the total requirement is increased. North American childhood diets generally contain more than adequate amounts of protein, but certain groups, including vegetarians, children with severe food allergies, those with limited access to foods, and children with severe food selectivity, are at risk for inadequate protein intake.
Fat requirements decrease from infancy through early childhood. Fat provides 40% to 50% of total calorie intake for infants. Restriction of fat intake in children under 2 years old is not advised because it may compromise growth. However, fat intake should gradually be decreased to approximately 30% by age 5 years and through adolescence. This decrease occurs as children transition from breast milk or infant formula during the first year, to whole milk during the second year, and then to lower fat milk after age 2. Low fat milk (2%) is recommended for children aged 1 to 2 years who are at risk of obesity or have a family history of lipid disorders, obesity, or cardiovascular disease. Intake of fruits, vegetables, and whole grains products should gradually increase.
Children from age 5 years to early adolescence grow slowly but steadily. During this age, they learn to eat by themselves and expand the spectrum of food groups they consume. It is widely noted that appetite drops and they become pickier. It is recommended that the diet include a variety of nutrient-dense foods and beverages from the basic food groups and the intake of saturated and trans fats, cholesterol, added sugars, and salt should be limited. In this age group, dietary intakes of iron, calcium, zinc, and vitamins B6, A, D, and C are less than recommended, but deficiencies are unlikely in most children in the United States because of easy access to fortified foods. Required quantities of vitamins and minerals are usually obtained from whole grain cereals, fruits, and vegetables.
Nutritional requirements for the preadolescent and adolescent age groups rapidly increase. Also, individual teenagers differ greatly depending upon their growth rate more than upon their chronological age. Needless to say, adolescence is very challenging because teens make ...