Early introduction of allergenic foods in exclusively breast-fed infants does not appear to reduce incidence of food allergy at age 3 years compared to introduction at 6 months

Resident Focus - Volume 13, Issue 3

Reference: N Engl J Med 2016 May 5;374(18):1733
Level 2 [mid-level] evidence

Food allergy (also called food hypersensitivity) is the most common cause of anaphylaxis in America, resulting in 30,000 reactions and 200 deaths each year (Pediatrics in Review 2003 Nov;24(11):393). Up to 6% of children ≤ 3 years old have had an allergic reaction to food, with prevalence being even higher in children with atopic disease such as eczema or asthma. Standard advice to parents has been to delay the introduction of common allergenic foods such as eggs and peanuts in an attempt to prevent food hypersensitivity. Presently, the World Health Organization recommends exclusive breastfeeding for the first six months of life (World Health Organization Statement 2011). Some studies suggest a reduced risk of peanut allergy with early exposure (J Allergy Clin Immunol 2008 Nov;122(5):984, N Engl J Med. 2015 Feb 26;372(9):803) and prompt the question: does introduction of allergenic foods earlier than 6 months of age decrease the development of food allergies when compared with exclusive breastfeeding in healthy infants?

The EAT trial randomized 1,303 exclusively breast-fed healthy term infants to introduction of allergenic foods at age 3 months or 6 months and followed them until age 3 years. Infants in the intervention group had introduction of 6 allergenic foods at 3 months of age (2 g twice weekly each): cow’s milk first, followed by peanut, egg, sesame, and fish in random order, and wheat last. Infants in the control group were exclusively breastfed for the first 6 months of life and then began consumption of allergenic foods at the parents’ discretion. All infants continued breastfeeding until at least 5 months. Skin prick testing for the 6 intervention foods was performed on all infants at the 1-year and 3-year visits and in the infants in the intervention group at 3 months of age. The control infants did not undergo testing at 3 months so as to not influence introduction of allergenic foods. Food allergy was diagnosed by blinded food challenges (95%) or wheal ≥ 5 mm on skin-prick test (5%). All participating families completed online questionnaires monthly until infants were age 1 year, and then every 3 months until age 3 years.

Of the enrolled infants, 89.2% completed the study and were included in an intention-to-treat analysis. Adherence (defined as consumption of ≥ 3 g/week of allergenic protein of ≥ 5 foods for ≥ 5 weeks) was 31.9% in the 3-month introduction group compared to 80.5% in the 6-month introduction group (no p value reported). The median age of introduction of allergenic foods in the early intervention group was 4-5 months. Comparing early introduction of allergenic foods vs 6 months in the intention-to-treat analysis of trial completers, there was no significant difference between the two groups in food challenge-proven allergy to one or more of the allergenic foods (5.6% vs 7.1%). Analysis of secondary outcomes (allergies to specific foods and positive skin prick testing for individual foods) also showed no significant difference between groups in any of the food allergies.

This randomized trial demonstrated no benefit of early introduction of allergenic foods compared to standard introduction at age 6 months based on intention-to-treat analysis. While early introduction of specific allergenic foods demonstrated some benefit in per-protocol analysis, consideration of potential reasons for the high rate of protocol non-adherence is critical, including the possibility that the first sign of clinical food allergy is aversive feeding behavior. Further, early introduction of allergenic foods in the real world would likely lack the strict adherence to food introduction order and amount, leading to even more uncertainty regarding the clinical applicability of these data.

For more information, see the Immunoglobulin E (IgE)-mediated food allergy in Dynamed Plus. DynaMed users, see the Immunoglobulin E (IgE)-mediated food allergy topic in Dynamed Classic.

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