Immunological considerations on breast vs. formula feeding.

The breast-fed baby is immunologically protected because the food is uncontaminated, because breast milk contains specific and unspecific constituents directed against microorganisms, toxins and food antigens, and because adverse immunological reactions against constituents of breast milk substitutes, as cow's milk proteins, are avoided. It is not known which of the mechanisms are the most important ones. Antiinfectious properties may also serve to protect the mammary gland. The documented lower morbidity of breast-fed compared to artificially fed infants in developing and developed countries is reviewed. Favourable immunological properties of human milk are sensitive to various ways of treatment, e.g. pasteurization. Exclusive breast feeding until several weeks or months of age appears to modify the relative risk of development of subsequent allergic disease, but the literature on this issue is not entirely conclusive. Breast feeding may also reduce the risk of developing other immunological disorders at later age, e.g. celiac disease and ulcerative colitis.