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Nutritional Requirements Throughout the Life Cycle: Infancy and Early Childhood

Requirements for macronutrients and micronutrients are higher on a per–kilogram basis during infancy and childhood than at any other developmental stage. These needs are influenced by the rapid cell division occurring during growth, which requires protein, energy, and nutrients involved in DNA synthesis and metabolism of protein, calories, and fat. Increased needs for these nutrients are reflected in DRIs for these age groups,1 some of which are briefly discussed below.

Energy. While most adults require 25 to 30 calories per kg, a 4 kg infant requires more than 100 kcals/kg (430 calories/day). Infants 4 to 6 months who weigh 6 kg require roughly 82 kcals/kg (490 calories/day). Energy needs remain high through the early formative years. Children 1 to 3 years of age require approximately 83 kcals/kg (990 kcals/day). Energy requirements decline thereafter and are based on weight, height, and physical activity.

As an energy source, breast milk offers significant advantages over manufactured formula. Breast–feeding is associated with reduced risk for obesity, 34 allergies, hypertension, and type 1 diabetes; improved cognitive development; and decreased incidence and severity of infections. It is also less costly than formula feeding.35

Water. Total water requirements (from beverages and foods) are also higher in infants and children than for adults. Children have larger body surface area per unit of body weight and a reduced capacity for sweating when compared with adults, and therefore are at greater risk of morbidity and mortality from dehydration.36 Parents may underestimate these fluid needs, especially if infants and children are experiencing fever, diarrhea, or exposure to extreme temperatures (eg, in vehicles during summer).

Essential fatty acids. Requirements for fatty acids on a per–kilogram basis are higher in infants than adults (see below). Through desaturation and elongation, linolenic and alpha–linolenic acids are converted to long–chain fatty acids (arachidonic and docosahexanoic acids) that play key roles in the central nervous system. Since both saturated fats and trans fatty acids inhibit these pathways,37 infants and children should not ingest foods that contain a predominance of these fats.


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