Timing of Introduction, Sensitization, and Allergy to Highly Allergenic Foods at Age 3 Years in a General-Population Canadian Cohort

Health Promotion of Early and Sustained Allergenic Food Introduction for the Prevention of Food Allergy

Observational studies and landmark randomized control trials support early and sustained allergenic food introduction in infancy as an effective preventive strategy against food allergy development. Despite a consensus regarding the intended goals of early and sustained allergenic food introduction, there have been myriad policy recommendations among health authorities in how to achieve both individual and population-level health outcomes for food allergy prevention. This clinical management review provides an overview on the data that informs early and sustained allergenic food introduction strategies, suggestions on how to advise allergenic food introduction, principles of prevention programs as they relate to food allergy prevention, and health promotion and systems-level challenges that impede achievement of food allergy prevention goals.

DNA methylation is not associated with sensitization to or dietary introduction of highly allergenic foods in a subset of the CHILD cohort at age 1 year

Background

In the first year of life, DNA methylation (DNAm) patterns are established and are particularly susceptible to exposure-induced changes. Some of these changes may leave lasting effects by persistently altering gene expression or cell type composition or function, contributing to disease.

Objectives

In this discovery study, we investigated DNAm associations with sensitization to peanut, egg, or cow's milk and hypothesized that genes demonstrating DNAm differences in immune cells may play a role in the development of food sensitization.

Methods

Infant sensitization (a skin prick test wheal size that is at least 2 mm greater than the negative control) was measured to peanut, egg, and cow's milk at age 1 year, and ages of food introduction were reported prospectively. PBMC DNAm was measured in blood samples at 1 year in 144 infants, oversampled for atopy or wheeze. Statistical analysis of Illumina 450k array DNAm data was conducted in R with adjustment for clinical and genetic covariables and a minimum effect size of 1%, false discovery rate of 5%, and medium-confidence false discovery rate threshold of 20%.

Results

There were no DNAm differences between infants with and without peanut, egg, or cow's milk sensitization. Borderline significant sites with high effect sizes were enriched for methylation quantitative trait loci, hinting at genetic factors influencing DNAm at these sites. DNAm patterns did not differ by peanut or egg introduction before or after 12 months.

Conclusion

This small pilot study did not show differences in methylation by food sensitization or introduction, but it did demonstrate DNAm patterns linked to genetic variants.

Early-life risk factors for food allergy: Dietary and environmental factors revisited

There appears a steep increase in the prevalence of food allergy worldwide in the past few decades. It is believed that, rather than genetic factors, the recently altered dietary and environmental factors are the driving forces behind the rapid increase of this disease. Accumulating evidence has implied that external exposures that occurred in prenatal and postnatal periods could affect the development of oral tolerance in later life. Understanding the potential risk factors for food allergy would greatly benefit the progress of intervention and therapy. In this review, we present updated knowledge on the dietary and environmental risk factors in early life that have been shown to impact the development of food allergy. These predominantly include dietary habits, microbial exposures, allergen exposure routes, environmental pollutants, and so on. The key evidence, conflicts, and potential research topics of each theory are discussed, and associated interventional strategies to prevent the disease development and ameliorate treatment burden are included. Accumulating evidence has supported the causative role of certain dietary and environmental factors in the establishment of oral tolerance in early life, especially the time of introducing allergenic foods, skin barrier function, and microbial exposures. In addition to certain immunomodulatory factors, increasing interest is raised toward modern dietary patterns, where adequately powered studies are required to identify contributions of those modifiable risk factors. This review broadens our understanding of the connections between diet, environment, and early-life immunity, thus benefiting the progress of intervention and therapy of food allergy.

Factors influencing age of common allergen introduction in early childhood

Objectives

We evaluated factors influencing the timing of allergen introduction in the U.S., including updated peanut introduction guidelines.

Study design

The Gastrointestinal Microbiome and Allergic Proctocolitis (GMAP) study is a prospective observational cohort in suburban Massachusetts. Infants' caregivers enrolled between 2014 and 2017, and they reported when they introduced common allergens to their child. Multivariable linear and survival regression analyses were used to examine factors influencing time of introduction of allergens.

Results

By 9 months, children old enough to be potentially affected by NIAID's 2017 peanut introduction guidelines were more often introduced to peanut than children enrolled well before guidelines publication [54% vs. 42%, OR: 1.63, CI: (1.03, 2.57), P = 0.03]. At any given time, Black children were 73% [HR: 0.27, CI: (0.11, 0.69), P = 0.006] less likely to be introduced to peanut as early as White children. Asian children were, respectively, 36% [HR: 0.64, CI: (0.47, 0.86), P = 0.003] and 26% [HR: 0.74, CI: (0.55, 0.97), P = 0.03] less likely to be introduced to peanut and egg as early as White children. A first child was 27% [HR: 1.27, CI: (1.04, 1.56), P = 0.02] more likely to have been introduced to peanut earlier than a non-first child. There was no association between age of introduction and sex, gestational age, family history of food allergy, or other allergic comorbidities.

Conclusion

Updated introduction guidelines, race, and birth order all influenced earlier introduction of peanut. Further studies to evaluate current practices for allergen introduction with a focus on potential disparities are needed.

Exclusive breast-feeding, the early-life microbiome and immune response, and common childhood respiratory illnesses

BACKGROUND

The impact of breast-feeding on certain childhood respiratory illnesses remains controversial.

OBJECTIVE

We sought to examine the effect of exclusive breast-feeding on the early-life upper respiratory tract (URT) and gut microbiome, the URT immune response in infancy, and the risk of common pediatric respiratory diseases.

METHODS

We analyzed data from a birth cohort of healthy infants with prospective ascertainment of breast-feeding patterns and common pediatric pulmonary and atopic outcomes. In a subset of infants, we also characterized the URT and gut microbiome using 16S ribosomal RNA sequencing and measured 9 URT cytokines using magnetic bead-based assays.

RESULTS

Of the 1949 infants enrolled, 1495 (76.71%) had 4-year data. In adjusted analyses, exclusive breast-feeding (1) had an inverse dose-response on the ⍺-diversity of the early-life URT and gut microbiome, (2) was positively associated with the URT levels of IFN-α, IFN-γ, and IL-17A in infancy, and (3) had a protective dose-response on the development of a lower respiratory tract infection in infancy, 4-year current asthma, and 4-year ever allergic rhinitis (odds ratio [95% CI] for each 4 weeks of exclusive breast-feeding, 0.95 [0.91-0.99], 0.95 [0.90-0.99], and 0.95 [0.92-0.99], respectively). In exploratory analyses, we also found that the protective association of exclusive breast-feeding on 4-year current asthma was mediated through its impact on the gut microbiome (P = .03).

CONCLUSIONS

Our results support a protective causal role of exclusive breast-feeding in the risk of developing a lower respiratory tract infection in infancy and asthma and allergic rhinitis in childhood. They also shed light on potential mechanisms of these associations, including the effect of exclusive breast-feeding on the gut microbiome.

Food Allergy Evaluation for Dermatologic Disorders

Food allergy evaluation for dermatologic disorders is warranted when Type 1 allergy is suspected, and includes skin prick testing (SPT) or measurement of specific immunoglobulin E (IgE) levels. The utility of these tests for identifying triggers is improved with clinical correlation, especially for contact urticaria, and protein contact dermatitis, which are mixed mechanism diseases. In atopic dermatitis (AD), patients are at risk for development of food allergy, and screening with SPT or IgE may be considered in severe AD, especially to guide early food introduction. Management of food-related AD exacerbations should focus on modifications in skincare before evaluating for allergy.

EAACI guideline: Preventing the development of food allergy in infants and young children (2020 update)

BACKGROUND

This guideline from the European Academy of Allergy and Clinical Immunology (EAACI) recommends approaches to prevent the development of immediate-onset / IgE-mediated food allergy in infants and young children. It is an update of a 2014 EAACI guideline.

METHODS

The guideline was developed using the AGREE II framework and the GRADE approach. An international Task Force with representatives from 11 countries and different disciplinary and clinical backgrounds systematically reviewed research and considered expert opinion. Recommendations were created by weighing up benefits and harms, considering the certainty of evidence and examining values, preferences and resource implications. The guideline was peer-reviewed by external experts, and feedback was incorporated from public consultation.

RESULTS

All of the recommendations about preventing food allergy relate to infants (up to 1 year) and young children (up to 5 years), regardless of risk of allergy. There was insufficient evidence about preventing food allergy in other age groups. The EAACI Task Force suggests avoiding the use of regular cow's milk formula as supplementary feed for breastfed infants in the first week of life. The EAACI Task Force suggests introducing well-cooked, but not raw egg or uncooked pasteurized, egg into the infant diet as part of complementary feeding. In populations where there is a high prevalence of peanut allergy, the EAACI Task Force suggests introducing peanuts in an age-appropriate form as part of complementary feeding. According to the studies, it appears that the most effective age to introduce egg and peanut is from four to 6 months of life. The EAACI Task Force suggests against the following for preventing food allergy: (i) avoiding dietary food allergens during pregnancy or breastfeeding; and (ii) using soy protein formula in the first 6 months of life as a means of preventing food allergy. There is no recommendation for or against the following: use of vitamin supplements, fish oil, prebiotics, probiotics or synbiotics in pregnancy, when breastfeeding or in infancy; altering the duration of exclusive breastfeeding; and hydrolysed infant formulas, regular cow's milk-based infant formula after a week of age or use of emollients.

CONCLUSIONS

Key changes from the 2014 guideline include suggesting (i) the introduction of peanut and well-cooked egg as part of complementary feeding (moderate certainty of evidence) and (ii) avoiding supplementation with regular cow's milk formula in the first week of life (low certainty of evidence). There remains uncertainty in how to prevent food allergy, and further well-powered, multinational research using robust diagnostic criteria is needed.

Insights into allergic risk factors from birth cohort studies

OBJECTIVE

To present an update of birth cohort study designs and their contributions to allergic risk.

DATA SOURCES

The PubMed database was used to search for relevant articles.

STUDY SELECTIONS

Peer-reviewed prospective and retrospective studies involving the assessment of allergy using human birth cohorts between 2014 and 2021 were evaluated.

RESULTS

Parental history of allergic diseases, especially in cases involving both parents, is associated with increased risk of allergy. Exposure to prenatal and postnatal smoking and limited diet diversity were associated with increased allergic burden. The impact of early-life infections and antibiotics on disease development may be associated with the onset of asthma, though this remains debated. Cohort studies also revealed that the mode of delivery and breastfeeding duration affect the odds ratio of asthma and eczema development. Household exposures, including pets, house dust mites, and scented aeroallergens may confer protective effects, whereas high air pollution exposure and low socioeconomic status may be risk enhancing. Exposure to antibiotics during early life may be associated with increased asthma risk, whereas viral infections may lead to disease protection, though the impact of the coronavirus disease 2019 pandemic on allergic risk is yet to be understood.

CONCLUSION

Although evaluating the risk of allergic disease development is complex, clinicians can apply these insights on the multifactorial nature of atopy to better understand and potentially mitigate disease development.

The global burden of illness of peanut allergy: A comprehensive literature review

Peanut allergy (PA) currently affects approximately 2% of the general population of Western nations and may be increasing in prevalence. Patients with PA and their families/caregivers bear a considerable burden of self‐management to avoid accidental peanut exposure and to administer emergency medication (adrenaline) if needed. Compared with other food allergies, PA is associated with higher rates of accidental exposure, severe reactions and potentially fatal anaphylaxis. Approximately 7%–14% of patients with PA experience accidental peanut exposure annually, and one‐third to one‐half may experience anaphylaxis, although fatalities are rare. These risks impose considerably high healthcare utilization and economic costs for patients with PA and restrictions on daily activities. Measures to accommodate patients with PA are often inadequate, with inconsistent standards for food labelling and inadequate safety policies in public establishments such as restaurants and schools. Children with PA are often bullied, resulting in sadness, humiliation and anxiety. These factors cumulatively contribute to significantly reduced health‐related quality of life for patients with PA and families/caregivers. Such factors also provide essential context for risk/benefit assessments of new PA therapies. This narrative review comprehensively assessed the various factors comprising the burden of PA.

Maternal awareness to the timing of allergenic food introduction in Saudi infants: A cross-sectional study

Background

Current guidelines recommend the introduction of allergenic foods as early as 4–6 months of age to decrease the risk of food allergy. However, caregivers’ knowledge about such practices and adherence to them is ambiguous.

Objectives

The purpose of this study was to evaluate the timing of introduction of potentially allergenic foods into children’s diet and the level of maternal awareness about and degree of compliance with current recommendations.

Materials and methods

We conducted a cross-sectional study from May 2019 to January 2020 at Imam Mohammad Ibn Saud Islamic University Medical Center, Riyadh, Saudi Arabia. Data were collected through questionnaire-based surveys, and a total of 405 mothers were enrolled in the study. The eligibility criteria included mothers of children between the ages of 12 and 36 months.

Results

Most mothers in this study had initiated allergenic foods, and the average time of introduction was 9.84 ± 3.16 months for eggs, 14.6 ± 5.78 months for peanuts, and 13.6 ± 5.37 months for fish. Around one-quarter (n = 102, 25.2%) of the children were identified as being in the high-risk group. Most mothers did not know or disagreed that the timing of introducing allergenic foods might help in preventing food allergy, but there was no difference between the risk groups (33.8% and 26.2%, respectively). Moreover, only 18.6% and 13.2% of the high- and low-risk groups, respectively, received correct information from their health care providers (P = .004). Mothers with only one child were less likely to start eggs at an early age (odds ratio [OR] = 0.5 and P = .005). Furthermore, children at a high risk of food allergy were two times more likely to start eggs at an earlier age (OR = 2.12 and P = .003).

Conclusion

In this study, the allergenic food feeding practices being followed for infants and young children were found to be suboptimal. Parental education level and the number of siblings were identified as potential barriers to the implementation of and adherence to recent guidelines. There is a need for corrective measures to ensure safe and appropriate feeding practices in the Saudi community.

Reduced peanut sensitization with maternal peanut consumption and early peanut introduction while breastfeeding

New guidelines for peanut allergy prevention in high-risk infants recommend introducing peanut during infancy but do not address breastfeeding or maternal peanut consumption. We assessed the independent and combined association of these factors with peanut sensitization in the general population CHILD birth cohort (N = 2759 mother-child dyads). Mothers reported peanut consumption during pregnancy, timing of first infant peanut consumption, and length of breastfeeding duration. Child peanut sensitization was determined by skin prick testing at 1, 3, and 5 years. Overall, 69% of mothers regularly consumed peanuts and 36% of infants were fed peanut in the first year (20% while breastfeeding and 16% after breastfeeding cessation). Infants who were introduced to peanut early (before 1 year) after breastfeeding cessation had a 66% reduced risk of sensitization at 5 years compared to those who were not (1.9% vs. 5.8% sensitization; aOR 0.34, 95% CI 0.14-0.68). This risk was further reduced if mothers introduced peanut early while breastfeeding and regularly consumed peanut themselves (0.3% sensitization; aOR 0.07, 0.01-0.25). In longitudinal analyses, these associations were driven by a higher odds of outgrowing early sensitization and a lower odds of late-onset sensitization. There was no apparent benefit (or harm) from maternal peanut consumption without breastfeeding. Taken together, these results suggest the combination of maternal peanut consumption and breastfeeding at the time of peanut introduction during infancy may help to decrease the risk of peanut sensitization. Mechanistic and clinical intervention studies are needed to confirm and understand this "triple exposure" hypothesis.

Food allergy prevention, including early food introduction

As the prevalence of immunoglobulin E (IgE)-mediated food allergy continues to increase without an imminent cure, prevention has become an urgent need. A breakthrough study that shows that early consumption of peanut can prevent the development of peanut allergy has led for a push in early interventions. Theories associated with the increasing prevalence of food allergy lend themselves to areas of potential intervention, e.g., age at time of food introduction, infant feeding practices, microbiome influences, diet composition, vitamin D deficiency, and increasing rates of eczema. This review focused on the available data from studies that investigated early interventions to decrease the risk of food allergy.