Breastfeeding, the immune response, and long-term health.

Breastfeeding provides unsurpassed natural nutrition to the newborn and infant. Human breast milk also contains numerous protective factors against infectious disease and may influence immune system development, as noted in previous studies of infant response to vaccination and thymus gland development. If immune system development is significantly improved with the introduction of components of breast milk, then prematurely discontinued breastfeeding may facilitate pathogenesis of many chronic diseases later in life (eg, autoimmune disorders). The authors summarize the reported effects of breastfeeding on the development of the suckling infant's immune system and discuss possible consequences to immunologic health when breastfeeding is discontinued prematurely.