Birch pollen allergy in children. Role of milk feeding during the first birch season of life.

The effect of exclusive breast-feeding throughout the first birch pollen season of life was examined in 59 children compared to 67 children on cow milk formula and to 27 children weaned to cow milk-based formula during their first birch season. The infants were about 3 months of age in their first birch season, and allergy to birch pollen was evaluated at 5 years of age by history and prick and provocation tests. Breast-feeding throughout the first birch season did not prevent birch pollen allergy; a similar birch allergy prevalence of about 10% was found in children initially fed on human or cow milk. Instead, weaning to cow milk-based formula during the first birch season seemed to protect from subsequent development of birch pollen allergy. Analogous results were obtained regarding allergy to grass pollen. This unexpected finding may be related to the immunologic stress on the young infant provided by introduction of cow milk proteins at an early age.