Cow's milk is dissimilar to human milk in all respects. Among the benefits of mother's milk is a generous supply of IgA, the protective antibody which the infant bowel lacks. This antibody helps to protect the infant from bacterial infection and probably reduces the entry of antigenic food protein fragments, reducing the incidence of food allergy. Breast feeding an infant for six months or longer appears to significantly reduce the incidence of infection and food allergy. In the first six months of life, infants are dependent upon breast milk or an infant formula substitute for their nutrients.
Infant growth is rapid and a continuous supply of nutrients is required.
An infant should double birth weight at six months, and triple birth weight at one year. Water is important to infants and should supplement breast or formula feedings. The advice to mothers to drink extra cow's milk may be harmful to the infant who may develop milk protein allergy. One problem with mother's milk is that it may contain allergens which the mother has absorbed intact. Allergens derived from cow's milk may appear in the mother's milk and sensitize her child.