Luke, what does Uncle Dave always say?
That’s exactly the advice I gave to my 2-year-old nephew when I first started my allergy/immunology fellowship a decade ago. After all, those were the recommendations published in 2000 from the American Academy of Pediatrics. To try and prevent the development of food allergies, the guidelines were no milk til age one, no eggs til age two, and no nuts, peanuts, or seafood until three years old! And pregnant mothers shouldn’t eat anything!!! (OK, not quite…but it was a confusing time).
Expert opinion at the time believed that avoiding highly allergenic foods until later in childhood would prevent the development of food allergies. Makes sense, right? If your immune system is never exposed, then how can it learn to become allergic?
Interestingly, within just 8 years, the American Academy of Pediatrics revised and published completely different guidelines for early feeding, when it was realized that there wasn’t much evidence to support avoidance. In fact, at the time, there was emerging evidence that perhaps early introduction could delay or possibly prevent the onset of food allergies. In 2008, the guidelines recommended a complete paradigm shift: instead of avoiding highly allergenic foods, you were told to incorporate them into your child’s diet at…4 to 6 months of age!
Needless to say, this was not only confusing for pediatricians and parents, but many were reluctant to follow such a dramatic change in advice.
Today, we have excellent data (finally, data!) that strongly shows early introduction of peanuts can, in fact, prevent the development of a peanut allergy. The Learning Early About Peanut Allergy (LEAP) study was published in the New England Journal of Medicine in March, which you can read about here in another The Scientific Parent post.
Briefly, here are the highlights of that LEAP study, which was the first large-scale study demonstrating the possibility of prevention of food allergy through early introduction:
- The trial enrolled 640 infants between the ages of 4-11 months, and randomized them to two groups: one group avoided any peanut consumption until 5 years of age and the other group consumed 2 grams of peanut 3 times a week until age 5.
- All participants had moderate-to-severe eczema and/or egg allergy and underwent skin prick testing and food challenge at enrollment (In other words, DO NOT try this at home!).
- The trial demonstrated a significant reduction in peanut allergy at 5 years of age for infants who consumed it regularly compared to those who avoided it.
Several questions remained after the LEAP study was published, however, such as: What happens if we feed infants peanuts who do not have eczema? Do they need to eat exactly 2 grams of peanut 3 times a week? What happens if they eat less? Or more? The LEAP study only enrolled infants less than 11 months of age – what will happen if we try this in older children who have yet to consume peanut? And perhaps most importantly, does the LEAP protocol truly prevent peanut allergy, or does it merely provide a prolonged desensitization?
One year later, most of these questions remain unanswered. However, the last question regarding mechanism of action (prevention vs. desensitization) was answered this year. The 2016 Persistence of Oral Tolerance to Peanut (LEAP-On) study used the same participants from LEAP, and asked all children in both the avoidance and consumption groups to strictly avoid peanut for 12 months, after their oral challenge at age 5. This was to try and determine whether their peanut allergy was truly prevented through the early introduction process, or whether these infants were being desensitized, similar to oral immunotherapy.
Here are the highlights from the LEAP-On Study:
- LEAP-On enrolled almost all (88.5%) participants from the original trial. Within the original peanut avoidance group, 90.4% continued avoidance compared with 69.3% in the peanut consumption group.
- After 12 months of peanut avoidance, there was no significant increase in development of peanut allergy within the children who had previously consumed it (3.6% at 5 years of age, compared with 4.8% at 6 years).
- There were a total of 3 new cases of peanut allergy in both groups. In addition, the original peanut consumption group continued to have much lower rates of peanut allergy after completion of LEAP-On (4.8% vs 18.6%).
So what does this all mean? According to the new data from LEAP-On, early introduction of peanut to infants at high risk for development of peanut allergy not only dramatically reduces rates of peanut allergy at 5 years of age, but this effect is sustained after one year of avoidance. This is likely due to true prevention, as opposed to a prolonged desensitization.
Prior to the publication of the LEAP-On data, an expert panel of food allergy experts and advocacy groups was convened in 2015 by the National Institute of Health to draft new guidelines for the introduction of peanut to prevent the development of peanut allergy. These guidelines were released for public comment on March 4, 2016 and will be published this year.
Here is a summary of the draft guidelines (yet to be published):
- Introduction of peanut into the diet of all infants before 12 months of age, ideally around 5-6 months of age.
- For infants not at high risk, such as those without eczema or other food allergies, consume an age-appropriate peanut-containing food without any prior testing, when developmentally ready.
- Infants with moderate-to-severe eczema and/or egg allergy (LEAP criteria) should be deemed at high risk for the development of peanut allergy and would most strongly benefit from early introduction. However, they should receive testing for peanut sensitization prior to introduction. Depending on the results of their serum IgE level or skin prick testing, a physician can help parents determine whether peanut can be introduced at home, under physician supervision, or not at all.
- Infants who are recommended to consume peanut should follow LEAP feeding practices with consumption of at least 2 grams of peanut protein (in an age appropriate food, not whole peanuts!) at least 3 times a week.
- It is important to note that these guidelines only apply to peanut introduction.
As these guidelines are finalized and then published and disseminated, parents and clinicians will all need to work together to increase awareness. It is also critically important to understand the various risks involved in early introduction, specifically the need to evaluate for the presence of peanut sensitization prior to its introduction in the infants at highest risk. Parents of newborns should discuss these implications with their child’s pediatrician or allergist prior to introducing peanut. Pediatricians should start discussing this with parents at the 4-month well child visit, and allergists can help educate everyone in regards to implementation.
The bottom line is, yes, early feeding of peanut to infants will undoubtedly cause angst with some parents or pediatricians. Yes, this is a complete reversal of advice from just a few years ago. And yes, if successful, and the LEAP data can be replicated on a population level, then we’re looking at the prevention of thousands of cases of peanut allergy every year.
This is truly an exciting time in the realm of food allergy research. While we all await a cure for food allergy, at least we have hope that perhaps we can prevent many in the next generation from developing food allergy altogether.