Breast feeding is considered beneficial in infants with atopic tendencies because human milk confers immunologic protection at the intestinal surface. This protection may continue beyond infancy. Yet allergy may develop in infants who are exclusively breast-fed, perhaps because they have become sensitized to dietary antigens in their mother's milk or because of the absence of some vital immunoregulatory components in the milk. Another possibility is that infants become sensitized by inhalation or direct allergen contact. Because of contradictory findings from previous studies of early sensitization and breast feeding, Isolauri and associates evaluated whether breast feeding should or should not continue in infants with atopic eczema.

Included in the study were 100 exclusively breast-fed infants with moderate or severe atopic eczema. The infants ranged in age from two weeks to six months (mean age: two months) when atopic eczema initially developed. Growth, nutrition and the extent of allergic sensitization were evaluated during and after breast feeding. In addition, the infants' mothers completed a questionnaire on their perceptions of their infants' symptoms. A family history of atopic disorders was verified in 77 of the patients. On the emergence of atopic eczema, all of the mothers modified their diets; 80 eliminated basic foods such as milk and milk products, eggs and fish, and 20 eliminated single foods such as citrus fruits.

Scores reflecting the severity of atopic eczema were higher during breast feeding than after breast feeding ceased. Fifty-nine of the infants were found to have cow's milk allergy. During breast feeding, the infants' growth was less than what would be expected for age during breast feeding, even though the amount of milk intake was not different from what would be expected. An association was found between the duration of symptoms and poor growth. With cessation of breast feeding, normal growth and nutritional parameters were restored, suggesting that sustained food allergy may cause poor growth in infants. Elimination diets undertaken by the mother did not produce a reversal in the sensitization that had already developed into allergic disease. Symptoms of atopic eczema decreased with cessation of breast feeding.

The authors conclude that there may be a delicate balance between immunoprotection and inflammatory response in breast-fed allergic infants. Breast feeding may maintain allergic symptoms in sensitized infants, which may impair their growth. In such infants, breast feeding should perhaps be stopped.