International agencies and various US health organizations uniformly recommend breastfeeding as the preferred method of infant feeding for the entire first year of life and thereafter as long as is beneficial to the mother–infant dyad.<sup>1 American Academy of Pediatrics Work Group on Breastfeeding Breastfeeding and the use of human milk Pediatrics 1997 ;  100 : 1035

Cliccare qui per andare alla sezione Riferimenti, 52US Department of Health and Human Services: Healthy People 2010, Washington, DC; 2000

Cliccare qui per andare alla sezione Riferimenti</sup> These recommendations are based on knowledge that term infants nursed by nutritionally adequate mothers are provided with sufficient energy and the proper profile of nutrients to support normal growth and development without any additional foods through the first 4 to 6 months of life. After 6 months, complimentary foods are needed to furnish nutrients likely to become limiting. Also, human milk furnishes an array of nonnutrient growth factors, immune factors, hormones, and other bioactive components that can act as biological signals and confer protection against illness in infancy and later in life.<sup>20 Hamosh M. Protective function of proteins and lipids in human milk Biol Neonate 1998 ;  74 : 163  [cross-ref]

Cliccare qui per andare alla sezione Riferimenti, 43 Rodriguez-Palermo M., Koletzko B., Kunz C. , e al. Nutritional and biochemical properties of human milk: II. Lipids, micronutrients, and bioactive factors Clin Perinatol 1999 ;  26 : 335

Cliccare qui per andare alla sezione Riferimenti</sup>

From a nutritional perspective, infancy is a critical and vulnerable period. At no other stage of life is a single food adequate as the sole source of nutrition. This phenomenon occurs when immaturity in tissues and organs involved in nutrient metabolism (i.e., the gastrointestinal tract, liver, and kidneys) limits the ability of an infant to respond to excesses or deficiencies in nutrient intakes. Human milk is species specific, and many of the nutrients it contains are secreted as bound components that can offer protection from digestion and facilitate absorption and utilization.

In this article, the characteristic nutritional features of human milk and influencing factors are reviewed. Knowledge of human-milk composition and nutrient intakes of thriving human milk–fed infants are central to the understanding of infant nutritional requirements and the nutritional cost of lactation for mothers.