Glucose is a primary direct source of energy, while galactose can be used for both energy and in many biosynthetic pathways. Vitamins Are completely adequate to cover the needs of the infant. No supplements are required. A general principle is that the infant's immune system is immature at birth and is much less able to ward off infection than adults are. Newborns receive some protection in utero through transfer of antibodies across the placenta, but this protection tapers off quickly after birth.
Breast milk contains a number of components to help protect the infant from pathogens.
Secretory IgA IgA is one of five classes of antibodies produced by the immune system. It is secreted into the lumen of the respiratory and gastrointestinal tracts, where it binds to pathogens and prevents them from penetrating the epithelium and entering surrounding tissues and the bloodstream. This IgA crosses the alveolar cells and is secreted into the milk, where it helps protect against pathogenic invasion through the infant's gastrointestinal tract. There are a wide variety of other antimicrobial molecules in breast milk, some of which can inhibit the growth of infectious agents and others which promote the growth of beneficial bacteria. Growth factors and other stimulatory factors, including epidermal growth factor, nerve growth factor, somatomedin C, and insulin-like growth factor, help accelerate maturation of the intestinal mucosa so it becomes less susceptible to attack.