Breast Milk: A vital defense against infection.

The protective agents in colostrum and mature breast milk include specific antibodies, enzymes, leukocytes and their products, antibinding factors, antiviral factors, promoters of a protective intestinal microflora, and immune stimulators. These agents persist through the length of the infant's digestive tract, are unaffected by gastric acid and digestive enzymes, are present throughout lactation, and protect by noninflammatory mechanisms.