Preventing Peanut Allergy: Where We Stand Now

Editor's Note
The author of this commentary, Matthew Greenhawt, MD, MBA, MSc, is a pediatric allergist at Children's Hospital of Colorado and an assistant professor at the University of Colorado School of Medicine. Dr Greenhawt serves on the National Institute of Allergy and Infectious Diseases (NIAID)-sponsored expert panel that has just released guidelines on prevention of peanut allergy.

Prevention of Food Allergy

The entire concept of preventing food allergy is an emerging field, and the issue received a huge boost in 2015 with the release of the Learning Early About Peanut Allergy (LEAP) study.^[1] As recently as 2000, the American Academy of Pediatrics (AAP) warned us to delay the introduction of such highly allergenic foods as peanut or eggs to children at risk of developing food allergy.^[2] In 2008, that policy was updated^[3] to note that there was no evidence to support delaying the introduction of any solid food past 4-6 months of life. Although the 2008 guidelines did not actively recommend when to introduce highly allergenic foods (eg, peanut, egg, fish, tree nut, etc.) to any infant, they did emphasize that parents of children at risk for allergic disease should consult with an allergist before starting these foods.

The LEAP study results have helped to fine-tune these recommendations for peanut. The LEAP study convincingly showed that not only was there strong evidence that peanut introduction between 4 and 11 months of life was protective for the development of peanut allergy, but more to the point, it highlighted that a prolonged delay in peanut introduction was associated with harm and a significantly increased risk for peanut allergy. Early peanut introduction was associated with an 86% risk reduction among children with no baseline positive peanut skin test and a 70% risk reduction among those with small positive baseline peanut allergy skin tests.

Given the tremendous positive results of the trial, multiple professional societies quickly created an international consensus statement^[4] of recommendations based on the study findings. This consensus communication emphasized that LEAP provided level-1 evidence from a randomized controlled trial supporting introducing peanut-containing products into the diets of "high-risk" infants between 4 and 11 months of age. This document was intended to provide interim guidance while an expert panel selected by NIAID would create a formal addendum on the subject to the 2010 food allergy guidelines.

Going Beyond Peanut

Many of us—allergists as well as primary care providers—wondered whether the benefit of peanut introduction would also be seen with early introduction of other allergenic foods, such as eggs. Data are emerging on this issue as well.

To date, there have been five randomized controlled trials^[5,6,7,8,9] of egg introduction between 4 and 6 months of life among children with high-risk factors for developing food allergy (including eczema in the infant) or a family history of allergy. These studies looked at rates of developing egg allergy and positive egg allergy tests at 1 year of life in infants fed egg compared with infants in a placebo group. Of these five trials, only one showed that early egg introduction was associated with a reduced risk of developing egg allergy—a study from Japan, which was stopped early because the benefit was so conclusive. The four other trials did not demonstrate any significantly reduced risk in developing egg allergy, with one study showing possible harm from early introduction.

A recent meta-analysis by Ierodiakonou and colleagues,^[10] from Imperial College in London, reviewed papers derived from 146 studies and provided some conclusions. The analysis was comprehensive and included the aforementioned peanut and egg trials, as well as the EAT study^[11] (a sister trial to LEAP, investigating introduction of multiple, sequential high-risk allergenic foods at either 3 months or 6 months in breastfed children with no known allergy risk factors). Ierodiakonou and colleagues concluded that there was strong, significant, protective benefit and reduced risk of developing food allergy associated with the introduction of egg between 4 and 6 months of life and peanut between 4 and 11 months of life. However, the authors suggested that the results should be interpreted with caution, given the relatively few studies that have been conducted and the fact that thousands more trial participants would be needed to reach a strong degree of certainty of the risk-reduction benefits.

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