[The protective effect of human milk against infections and its potential causes (author's transl)].

The protective effect of breast feeding against infections is well proved by the experiences in underdeveloped countries and in industrial countries as well as shown by numerous investigations in several populations of different social structure. Various factors are meant to be responsible for this special property of human milk, the importance of which is to be discussed. The lysozyme and the lactoferrin are two different antibacterial factors well known since a long time, the former of which is mainly directed against grampositive organisms and against gramnegative ones only under special conditions. Lactoferrin is effective against E. coli and Staphylococcus as well. The neuraminic acid of which the human milk contains a larger quantity than cow's milk also inhibits the growth of E. coli and Staphylococcus. A further factor consisting of isomers of linoleic acid protects mice against lethal Staphylococcus - infections. The most important antibacterial principles of human milk are meant to be specific immunoglobulins, specially secretory IgA. The immunoglobulins are mainly important for the young baby in the early stage of life. The fecal bifidusflora specific for the breast-fed infant is also meant to be protective against several infections. The factors of human milk provoking this special kind of intestinal flora are to be discussed. In the artificial-fed infant bifidus flora like that of breast-fed one can arise by application of lactulose. Nowadays, bifidus-flora can probably be obtained by application of beta-lactose. It is suggested, that infants with bifidus-flora provoked by one of this means are protected against intestinal infections. The results of all investigations on mother's milk lead to the conclusion, that breast-feeding is the optimal kind of alimentation in the first time of life, not only concerning the composition of the food, but concerning protection against infections.