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For the first 6 months after birth, breast milk or infant formula is the primary source of nutrients for optimal growth. Despite successful efforts to increase breastfeeding to levels that exceed 90% in developing countries and 50% to 90% in industrialized countries following birth, fewer than half of infants in many countries are exclusively breastfed by 3 to 4 months postpartum. Thus, infant formulas provide a significant portion of the nutrient intake for many infants. Infant formulas are designed to be an acceptable substitute for human milk. Their use is indicated for (1) infants whose mothers choose not to breastfeed; (2) infants for whom human milk is contraindicated; (3) infants who require a supplement to human milk because of slow growth; and (4) infants whose mothers choose to discontinue breastfeeding before the infant is 1 year old. All infant formulas are nutritionally complete and have concentrations of macronutrients (protein, fat, and carbohydrate) that are similar to breast milk. Infant formulas are the only acceptable alternative nutrient source for infants who are unable to take breast milk.
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Guidelines for specific nutrient intakes for infants are detailed in Chapter 15. Infant formulas are regulated by the US Food and Drug Administration (FDA) and the European Food Safety Authority to ensure that they provide adequate nutrients at optimum bioavailability for complete nutrition for the first 4 to 6 months after birth. Regulatory requirements include (1) nutrient content and quantity requirements, with minimum levels for 29 nutrients and maximum levels for 9 nutrients; (2) quality control procedures ensuring bioavailability of nutrients, adequate content throughout the shelf life of the product, and avoidance of contamination; (3) record keeping on testing; (4) recall procedures for removal of unsafe formulas; and (5) labeling requirements.
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Infant formulas commonly available in the United States are detailed in Table 17-1. They generally are available in ready-to-feed, powder, and liquid concentrate forms. Nutrient composition is nearly identical among the various formulations within any specific formula brand, although there may be small differences due to technological requirements in production. The Pediatric Nutrition Handbook from the American Academy of Pediatrics (AAP) reports the caloric density of human milk as ~19.2–20.7 kcal/fl oz with an osmolarity of 280 to 300 mOsm/kg. Some standard infant formulas contain 19 kcals/oz and others 20 kcal/oz; refer to Table 17-1 for specific formula compositions. Infant formulas can be categorized as either standard term infant formulas or specialized formulas. Standard term infant formulas are further categorized according to their protein type and composition: cow-milk based, soy based, hydrolyzed, or elemental or amino-acid based. Specialized formulas have altered macronutrient or electrolyte content specific for management of a medical condition.
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