Early allergen introduction for infants: Tips for breastfeeding parents with food allergies themselves

Consider the following clinical scenario, a breastfeeding parent with an immunoglobulin E (IgE)-mediated peanut allergy is considering introducing commonly allergenic foods to their infant. The parent is concerned that if the infant ingests peanut and subsequently feeds at the breast, it may cause an anaphylactic reaction in the parent. This raises an important question: Does early introduction of allergenic foods pose a safety concern for breastfeeding parents with food allergies themselves? For the primary prevention of food allergy in higher-risk infants (those with a personal history or a first degree relative with allergic disease, such as eczema, food allergy, allergic rhinitis, or asthma), current Canadian guidelines recommend that non-choking forms of all commonly allergenic foods are introduced around 6 (but not before 4) months of age and fed regularly (at least once per week, ideally ≥twice per week) (1,2). This may pose challenges for breastfeeding parents with a food allergy themselves. Food Allergy Canada recommends that families with a parent with food allergy safely introduce commonly allergenic foods by ensuring proper hand washing with soap and warm water for all family members before and after eating the food, careful cleaning of surfaces, and having designated eating areas such as highchairs or tables (3). Some families with an allergic parent may choose to have a non-allergic caregiver feed the allergenic food outside the home once it has been introduced and safely tolerated (3). The Australasian Society of Clinical Immunology and Allergy further recommends washing the baby’s face after giving the food, and thoroughly washing all utensils used to feed the allergic food in warm soapy water (4). These resources, however, do not provide specific guidance for breastfeeding parents with a food allergy. Although relatively rare, case studies and survey-based studies have demonstrated that individuals with food allergies can develop allergic symptoms (such as swelling of the lips, perioral itching, urticaria, and wheezing) following a kiss from an individual who had consumed the allergen within minutes to two hours prior to the kiss (5–8). Furthermore, a study by Maloney et al. demonstrated that Ara h1, a major peanut allergen, was detectable in saliva following oral ingestion of two tablespoons of peanut butter (9). In this study, despite significant interindividual variability, 87% of participants had undetectable salivary Ara h1 levels within one hour post-ingestion, without intervention (9). Five interventions, which included brushing teeth, brushing and rinsing, rinsing alone, waiting and then brushing, and waiting and chewing gum, were tested, and all interventions significantly reduced salivary Ara h1 levels, with the greatest reduction observed after waiting 60 minutes and then brushing teeth (9). However, waiting several hours and consuming a peanut-free meal was more effective than any of the tested interventions (9). Maloney et al. estimated the amount of peanut protein in 1mL of saliva immediately after eating the peanut butter was 8mg (9). In a study evaluating the amount of peanut protein necessary to elicit an allergic reaction, ingestion of 7mg of protein elicited an IgE-mediated reaction in 10% of peanut allergic patients (10). Thus, the protein amount that could theoretically be transferred back to the breastfeeding parent via retrograde flow of milk from the infant’s oral cavity into the breast during breastfeeding would be unlikely to elicit an IgE-mediated reaction in the majority of allergic individuals, though reports of reactions following kissing exposures suggest the risk cannot be ruled out entirely. While parent IgE-mediated reaction from allergen transfer through breastfeeding is unlikely, contact urticaria or IgE-mediated reactions through food contact in the environment can occur (11). Contact urticaria may occur if there is residual food on the infant’s face or hands, which then contact the parent’s skin. If this residual food meets the parent’s mucosal membranes, an IgE-mediated reaction may occur. This additionally raises the concern of breastfeeding with cracked or damaged nipples. The broken skin could theoretically allow allergens to penetrate and interact with immune cells, potentially leading to a systemic IgE-mediated reaction more easily, though, to our knowledge, no specific cases of this scenario are currently published. One possible approach to preventing this scenario is the regular use of nipple cream to prevent cracked nipples. Breastfeeding parents with food allergies can be reassured that their risk of experiencing an allergic reaction while breastfeeding is low. They should be encouraged to introduce commonly allergenic foods into their infants’ diet to support the prevention of IgE-mediated food allergies. Recognizing that some may still feel anxious about this process, we provide practical recommendations to help minimize the risk of allergic reactions (Table 1). Practical tips for breastfeeding parents with food allergies introducing commonly allergenic foods to their infant Practical tips for breastfeeding parents with food allergies introducing commonly allergenic foods to their infant No funding to report. B.A.W. is supported by a Canadian Institutes of Health Research Fellowship (#206427). B.A.W. and C.H. have no conflicts to declare. E.S.C. has received research support from DBV Technologies, has been a member of advisory boards for Pfizer, Miravo, Medexus, Leo Pharma, Kaleo, DBV, AllerGenis, Sanofi, Bausch Health, Avir-Pharma, AstraZeneca, ALK, Alladapt, and was co-lead of the CSACI oral immunotherapy guidelines; S.C.E. has received an education grant from Pfizer, a research grant from Avir-Pharma, and has been a member of an advisory board for ALK.

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