Date Published: September 12, 2018
Publisher: BioMed Central
Author(s): Edmond S. Chan, Elissa M. Abrams, Kyla J. Hildebrand, Wade Watson.
Food allergy is a growing public health problem, and in many affected individuals, the food allergy begins early in life and persists as a lifelong condition (e.g., peanut allergy). Although early clinical practice guidelines recommended delaying the introduction of peanut and other allergenic foods in children, this may have in fact contributed to the dramatic increase in the prevalence of food allergy in recent decades. In January 2017, new guidelines on peanut allergy prevention were released which represented a significant paradigm shift in early food introduction. Development of these guidelines was prompted by findings from the Learning Early About Peanut Allergy study—the first randomized trial to investigate early allergen introduction as a strategy to prevent peanut allergy. This article will review and compare the new guidelines with previous guidelines on food introduction, and will also review recent evidence that has led to the paradigm shift in early food introduction.
Peanut allergy is a potentially anaphylactic food allergy which is very difficult to outgrow once acquired . Although overall mortality due to peanut allergy is low, the fear of life-threatening anaphylactic reactions contributes significantly to the medical and psychosocial burden of this condition . Early clinical practice guidelines recommended delaying the introduction of peanut-containing foods until the age of 3 years . However, this recommendation was based on expert opinion only and likely resulted, at least in part, to the increase in peanut allergy over the last 20 years. Recently, results from the landmark Learning Early About Peanut (LEAP) study has provided Level 1 evidence (i.e., evidence from a high-quality randomized trial or prospective study) to support a paradigm shift for the early introduction of foods . LEAP, which was the first randomized trial to study early allergen introduction as a preventive strategy, found that the introduction of peanut at 4–11 months of age significantly reduced the risk of developing peanut allergy in high-risk infants. Given the large number of study participants and the observed treatment effect, LEAP received extensive publicity, which resulted in the need to develop clinical practice recommendations that would help operationalize the study findings. To achieve this goal, the National Institute of Allergy and Infectious Diseases (NIAID) convened members of the Guidelines Committee and numerous other stakeholder organizations, including the Canadian Society of Allergy and Clinical Immunology (CSACI), to develop addendum guidelines on peanut allergy prevention . These NIAID-sponsored guidelines represent a dramatic shift from previous advice to parents and caregivers regarding the introduction of peanut in children. This article will review and compare the new addendum guidelines with previous guidelines on food introduction, and will review recent evidence from observational studies and randomized controlled trials that has led to the paradigm shift in early food introduction. Potential challenges in implementing the new guidelines are also discussed, and key take-home messages for practitioners are provided.
Previous guidelines defined an infant at high risk of developing food allergy as one with a first-degree relative (at least one parent or sibling) with an allergic condition such as atopic dermatitis, food allergy, asthma or allergic rhinitis [5, 6]. The recent NIAID-sponsored addendum guidelines have defined “at-risk” infants very differently. According to these new guidelines, a “high risk” infant is defined as one with severe eczema and/or egg allergy, and an “at-risk” infant is defined as one with mild or moderate eczema . These addendum guidelines have not included a younger sibling of a child with peanut allergy in the high-risk definition since younger siblings described in previous studies may have been at increased risk due to delayed peanut introduction .
In 2000, the American Academy of Pediatrics (AAP) recommended delaying the introduction of peanut until 3 years of age . This advice was based on expert opinion rather than on prospective clinical trials, and likely contributed to the increase in the prevalence of peanut allergy in recent decades. In 2008, the AAP partially reversed the 2000 recommendation, stating that the introduction of allergenic foods “should not be delayed” . However, there was insufficient data available at that time to strongly recommend that peanut “should” be introduced at approximately 6 months of age, resulting in continued confusion regarding implementation of this guideline recommendation.
Given the surmounting evidence demonstrating the benefit of early allergenic food introduction—particularly the findings of the landmark LEAP study—the NIAID released addendum guidelines for the prevention of peanut allergy in January 2017 . These guidelines were developed in collaboration with numerous stakeholder organizations, including the CSACI for the first time. The NIAID-sponsored addendum guidelines aimed to improve implementation by providing parents and practitioners with specific guidance on when, where and how to introduce age-appropriate peanut-containing foods. The new guidelines recommend that the highest risk infants—those with severe eczema and/or egg allergy—be introduced to age-appropriate peanut-containing food (see Table 1) as early as 4–6 months of age to reduce the risk of peanut allergy . To demonstrate that the infant is developmentally ready for peanut, it is recommended that other solid foods be introduced before peanut-containing foods. For this high-risk group, allergy testing is strongly advised prior to peanut introduction. Although the preferred test is the SPT, peanut-specific IgE (sIgE) blood testing is also recommended in non-allergist settings such as family medicine, pediatrics, and dermatology, since it is more widely available. Based on these test results, either home or physician-supervised feeding is advised (see Fig. 1). Allergy tests for multiple foods other than peanut are not recommended because of their poor positive predictive value, which could lead to misinterpretation, overdiagnosis of food allergy, and unnecessary dietary restrictions .Table 1Typical peanut-containing foods, their peanut protein content, and feeding tips for infants Peanut butterPeanutsPeanut flour or peanut butter powderBambaAmount containing approximately 2 g of peanut protein9–10 g or 2 teaspoons8 g or ~ 10 whole peanuts (2½ teaspoons of grounded peanuts)4 g or 2 teaspoons17 g or 2/3 of a 28-g (1-oz) bag or 21 sticksTypical serving sizeSpread on a slice of bread or toast (16 g)2½ teaspoons of ground peanuts (8 g)No typical serving size1 bag (28 g)Peanut protein per typical serving3.4 g2.1 gNo typical serving size3.2 gFeeding tips• For a smooth texture, mix with warm water (then let cool) or breast milk or infant formula• For older children, mix with pureed or mashed fruit or vegetables or any suitable family foods, such as yogurt or mashed potatoes • Use blender to create a powder or paste• 2-2½ teaspoons of ground peanuts can be added to a portion of yogurt or pureed fruit or savory meal• Mix with yogurt or applesauce• For a smooth texture, mix with warm water (then let cool) or breast milk or infant formula and mash well• Pureed or mashed fruit or vegetables can be added• Older children can be offered sticks of BambaBamba (Osem, Israel) is named because it was the product used in the LEAP trial and therefore has known peanut protein content and proven efficacy and safety. Other peanut puff products with similar peanut protein content can be substituted for BambaTeaspoons and tablespoons are US measures (5 and 15 mL for a level teaspoon or tablespoon, respectively)Adapted from: Togias et al. Fig. 1Recommended approaches for when and where to introduce peanut and for the evaluation of children with severe eczema and/or egg allergy before peanut introductionAdapted from: Togias et al. 
Although the new addendum recommendations represent a major advance in the field of food allergy prevention, several experts have expressed concerns with respect to the feasibility and implementation of these guidelines [28–31]. Firstly, the prevalence of severe eczema is much lower than what most parents and practitioners believe it to be. LEAP investigators have estimated the prevalence of severe eczema to be approximately 5% . However, calculations based on the prevalence of eczema in the US population suggest that only 0.9% of all infants have severe eczema, with approximately 12% and 87% having mild-to-moderate eczema or no eczema, respectively . Therefore, only a very small subset of infants will require in-office testing and medically supervised peanut introduction and, as such, the vast majority of infants can have peanut introduced safely at home. Misunderstanding or misinformation among both parents and clinicians could result in many infants being misclassified as being at high-risk, leading to unnecessary screening and specialist referrals and, ultimately, delayed food introduction [34, 35]. Delaying the introduction of peanut and other solid foods due to misclassification will result in a missed opportunity for food allergy prevention. The CSACI has recently circulated a survey to examine how Canadian allergists, pediatricians, and family physicians approach early peanut introduction in their patients.
The increase in food allergy, particularly peanut allergy, prevalence in recent decades is a major public health problem and may, in part, be due to years of recommending delayed introduction of foods based on expert opinion only. Recent findings from observational studies, randomized controlled trials, and a meta-analysis now suggest that early introduction of allergenic foods is a potentially effective strategy for combating the rising rates of food allergy. The NIAID-sponsored addendum guidelines for the prevention of peanut allergy have led to a paradigm shift in food allergy prevention. These are the first guidelines to firmly recommend that parents “should” introduce non-choking forms of peanut at approximately 6 months of age, rather than the non-specific “don’t delay” message from a decade ago. Also, according to these guidelines, the vast majority of infants can have peanut introduced safely at home. This will help ensure that the window of opportunity for food allergy prevention is not missed due to delays in accessing specialty care and/or in-office allergy testing.
The vast majority of infants should have non-choking forms of peanut introduced at home, in an age-appropriate way, at approximately 6 months of age.It is likely best to also introduce other allergenic foods (e.g., dairy, egg, non-choking forms of tree nuts, etc.) without delay (also at approximately 6 months of age).Only a small subset of infants with severe eczema (~ 0.9%) and/or egg allergy (i.e., high-risk infants) need in-office testing, medically supervised peanut ingestion and/or an OFC.If an OFC is required, it should ideally be performed on the same day (or as soon as possible) as the first visit/SPT.Once introduced and tolerated, it is essential that peanut-containing foods (and other allergenic foods) be eaten regularly (e.g., 3 times per week) in amounts representative of age-appropriate servings.Please see Atopic Dermatitis article in this supplement for a discussion of early moisturizing to prevent atopic dermatitis, which could potentially help prevent food allergy as well.