Effects of Breastfeeding on the Baby and on Its Immune System

Human milk is a very complex fluid with a number of components and multiple functions. New functions are continually being identified. It is clear that human milk can affect the immune system of the breasfed infant. This results both in enhanced vaccine responses and, at times, down-regulation of other immune reactivities, such as transplant rejection and the risk of developing certain immunologic diseases, such as type I diabetes. Breastfeeding presumably gives the infant the possibility for an optimal immune response by providing good nutrition, including a decreased risk of vitamin A deficiency. The control of the intestinal flora and the anti-inflammatory effects of maternal milk also increase the possibilities for an adequate immune response in the infant. Further study is needed of the roles of idiotypic and anti-idiotypic antibodies, growth factors, cytokines, and various anti-inflammatory factors in the maternal milk in the infant's host defence.