Abstract
Optimal nutrition during infancy is critical not only to support the dramatic growth and development that takes place during the first 12 months following birth but also for establishing a healthy immune response throughout childhood and across the life span. The normative standards for infant feeding and nutrition are breast-feeding and human breast milk. However, in cases in which human breast milk is not available, infant formula is substituted. Providing optimal patient care that results in the best clinical outcomes depends on understanding the unique attributes of the 3 main sources of nutrition for newborns. This state of the science review provides an update on the macronutrient and immunological content of human milk, donor milk, and infant formula and highlights the relevance of these sources of infant nutrition on the development of immune system.