In a complete reversal based on research, in 2017 experts recommended that infants at high risk of developing peanut allergy instead be fed foods containing peanuts as early as four to six months of age. Apparently, oral exposure to peanuts in these children doesn’t trigger a life-threatening reaction, but rather desensitizes the child to peanuts. In other words, by eating peanut products at a young age, infants at high risk for peanut allergy become tolerant. Before we begin, let’s make a couple of points abundantly clear. First, infants shouldn’t be fed whole peanuts or whole peanut butter, which are both choking hazards, and instead be fed peanut-containing foods, such as watered-down peanut butter or peanut puffs. Second, before any infant is fed peanut products, he must first be developmentally ready and able to consume solid foods.
Peanut Allergies on the Rise
In a 2010 article published in The Journal of Allergy and Clinical Immunology, researchers found that the prevalence of peanut allergy among U.S. children had risen from 0.4 percent in 1997 to 1.4 percent in 2008, a figure that represents millions of kids. Of note, similar high frequencies have been recently documented in other countries, too, including Canada, the United Kingdom, and Australia. Apparently, the increased prevalence of peanut allergy has nothing to do with the availability of peanuts, which has remained constant during the past 40 years. According to the researchers: Hypotheses as to the reason for the increased rate of peanut allergies in children include increased allergenicity of roasted forms of peanut, early introduction of a peanut when the immune system is immature, delayed introduction of peanut into the diet, and environmental exposures to peanut without ingestion.
LEAP Study
Results from Learning Early about Peanut Allergy (LEAP) Study published in The New England Journal of Medicine in 2015 turned expert understanding of childhood peanut allergy on its head. In this randomized trial, researchers assigned 640 infants with severe eczema, egg allergy, or both—all indicators of peanut allergy risk—to either an experimental group, in which infants were fed peanut products, or a control group, in which children avoided peanut products until 60 months of age. The researchers found that the early introduction of peanut products in children who were at high risk for peanut allergy significantly decreased the development of such allergy as well as modulating immune responses to peanuts. The inspiration for this study came from previous research done by the researchers that demonstrated the risk of developing peanut allergy was 10 times higher among Jewish children living in the United Kingdom than it was among Israeli children of similar ancestry. The main difference between these two populations was that Jewish children in the United Kingdom typically didn’t consume peanuts during the first year of life; whereas, in Israel, peanuts were introduced in the diet at seven months of age.
Dual-Allergen Exposure Hypothesis
The reason why infants at high risk for peanut allergy are less likely to develop such allergy if fed peanut products early likely have to do with the dual-allergen exposure hypothesis. Essentially, peanut allergens can be introduced to a high-risk infant in two ways. First, because those who are at high-risk for peanut allergy often have eczema, or rash, peanut protein from the environment (e.g., peanut residue on tables or peanut oil in creams) can make its way across breaks in skin. Second, peanut proteins can be consumed by mouth. If children who are at high risk of peanut allergy are directed to avoid consumption of peanut products, the only way peanuts make their way into the blood is by skin exposure. According to the dual-allergen exposure hypothesis, this route of exposure is more likely to result in allergic sensitization and peanut allergy development. On the other hand, early oral exposure to peanut protein results in tolerance. In other words, an infant at high risk of peanut allergy who isn’t fed peanut products in her diet is still exposed to peanut protein in the environment. This exposure can lead to allergy. However, if she is fed peanut products, she becomes desensitized to peanuts and tolerance develops.
Three Guidelines
In light of the results of the LEAP Study as well as concerns about the increasing rates of peanut allergy, in January 2017, an expert panel and a coordinating committee convened by the National Institute of Allergy and Infectious Diseases issued a “peanut allergy” addendum to 2010 guidelines originally detailing the diagnosis and management of food allergies. This addendum proposes three new clinical practice guidelines. Guideline 1 recommends that if an infant has severe eczema, egg allergy or both—and thus is at higher risk for peanut allergy—then peanut-containing foods should be introduced into the diet as early as 4 to 6 weeks of age to mitigate the risk of developing a peanut allergy. Specifically, a physician will either first perform an allergy blood test or refer the child to a pediatric allergist who can do skin testing to determine whether it is safe for the infant to consume peanut protein as well as how to safely introduce peanut-containing foods into the diet. Importantly, some infants who are introduced to peanuts develop such severe allergic reactions during testing (very large skin wheals) that they definitely already have a peanut allergy and simply can’t tolerate the introduction of peanuts into the diet without the risk of anaphylaxis. Guideline 2 suggests that if an infant has moderate eczema, then peanut-containing foods should be introduced into the diet at around 6 months of age to reduce the risk of developing a peanut allergy. However, the introduction of peanut protein into the diets of infants with moderate eczema and lower risk of developing peanut allergy isn’t as exigent as if the child were to have severe eczema and a higher risk of peanut allergy. In infants with moderate eczema, the introduction of peanut-containing foods need not necessarily be rushed—especially if peanut-containing foods aren’t a part of the family’s regular diet. As with infants who have severe eczema, the introduction of peanut products into the diets of children with moderate eczema can first be done at home or during a feeding at the physician’s office depending on physician and patient preference. With relation to Guidelines 1 and 2, please keep in mind that determination as to whether patient eczema is severe or mild is made by the clinician. Guideline 3 suggests that in children without eczema or food allergy, peanut-containing products be introduced in an age-appropriate manner and together with other solid foods depending on the family’s dietary practices and routines.
Bottom Line
Peanut allergy takes a large psychosocial and economic toll on countless families not only in the United States but also worldwide. In the majority of people with peanut allergy, the allergy starts during childhood and persists throughout life. The prevalence of peanut allergies has substantially increased during the past several years. Before 2008, children who were at higher risk for peanut allergy were advised to avoid foods containing peanuts and peanut proteins. However, we now know that in certain infants at higher risk for peanut allergy, early introduction of peanut-containing foods into the diet can actually build a tolerance. The implications of this finding are profound, and, in the future, the early introduction of peanut protein into the diets of those at risk for peanut allergy may actually decrease rates of peanut allergy. If your child doesn’t have a peanut allergy but is at risk for it (think eczema, egg allergy or both), it’s a good idea to meet with your physician to discuss the introduction of peanut protein into her diet.
