There is no evidence to show that foods eaten by mothers either during pregnancy or while breastfeeding can induce allergy in their unborn or breastfed babies. Recent research in maternal peanut consumption suggests otherwise. Introduction of small amounts of potentially allergenic proteins may actually induce tolerance and not sensitization.
The incidence of allergic disease has increased dramatically in recent years. Although genes play an important role, the reasons for the increase are unclear. If the mother has a strong family history of allergic disease, she might be encouraged to follow certain guidelines in an effort to limit the onset and reduce the severity of allergic symptoms in her baby.
The importance of breastfeeding for all moms and babies cannot be overstated. Admittedly, breastfeeding will not prevent the occurrence of allergic disease in babies with a strong family history of allergy, but exclusive breastfeeding for the first six months and continued breastfeeding for at least the first year may delay the onset of allergic symptoms (gas, diarrhea, vomiting, fussiness, and skin rashes) and reduce their severity.
Research shows that food proteins can appear in human milk in small amounts. In extremely sensitive babies, the amount of protein can be large enough to cause allergic symptoms. Parents of babies at-risk of peanut allergy have long been cautioned not to introduce solid foods too soon. However, recent studies suggest that delaying the introduction of foods other than human milk beyond six months may actually increase the risk for allergic disease. It appears that when the immune system is exposed to foreign proteins (antigens) during a specific time period (not too early, not too late), a tolerance to the antigens rather than sensitivity may actually develop.
Because our understanding of allergic disease is constantly changing, mothers of high-risk babies (especially those with eczema or other skin conditions, and/or egg allergy) should be advised to talk with their baby’s doctor before introducing any foods other than human milk.