Exploration of parent-reported food allergy symptoms via breastmilk exposures and likelihood to develop tolerance

Background: Knowledge is limited about the relationship between clinical reactivity to foods through breastfeeding and long-term food allergy outcomes. We explored parent-perceived symptoms of food allergy via breastfeeding and the association with future tolerance. Methods: Subjects identified from the Chicago Food Allergy Study (2005–2011) were categorized by parent-reported reactions to maternally ingested foods via breastfeeding (50/898 peanut-allergic, 69/620 egg-allergic, and 153/589 milk-allergic). The primary outcome was tolerance [passed oral food challenge (OFC) or consumption of previously implicated food]. Secondary outcomes included severe reactions (anaphylaxis and/or cardiovascular/respiratory symptoms) and additional concomitant food allergies. Univariate chi-square analyses were performed to assess for association between variables, followed by logistic regression models. Results: Of the 50 subjects with parent-reported peanut-associated symptoms with breastfeeding, none gained tolerance. There were no significant associations between parent-reported breastfeeding symptoms and development of tolerance for egg and milk (egg: OR 0.46, 95% CI 0.21–1.01, p = 0.053; milk: OR 1.13, 95% CI 0.70–1.81, p = 0.614). All egg-allergic subjects with parent-perceived symptoms while breastfeeding also reported multiple food allergies (n = 69), but milk- and peanut-allergic subjects were not more likely to have multiple allergies (milk: OR 1.89, 95% CI 0.88–4.02, p = 0.10; peanut: OR 2.36, 95% CI 0.72–7.76, p = 0.16). There were no significant associations between parent-reported breastfeeding symptoms and subsequent reaction severity. Conclusions: A significant proportion of parents perceive symptoms of food allergy attributable to indirect breastfeeding exposures. Our exploratory analysis suggests that infants with parent-perceived clinical reactivity to peanut via breastmilk may be less likely to gain tolerance. Infants with parent-reported reactivity to egg via breastmilk exposure were more likely to report multiple food allergies. Further rigorous prospective studies are needed to clarify the true prevalence of IgE-mediated food allergy symptoms attributable to indirect breastfeeding exposures and the association with development of tolerance.