Prospective study of peripregnancy consumption of peanuts or tree nuts by mothers and the risk of peanut or tree nut allergy in their offspring

Maternal influences on offspring food allergy

The prevalence of allergies has been globally escalating. While allergies could appear at any age, they often develop in early life. However, the significant knowledge gap in the field is the mechanisms by which allergies affect certain people but not others. Investigating early factors and events in neonatal life that have a lasting impact on determining the susceptibilities of children to develop allergies is a significant area of the investigation as it promotes the understanding of neonatal immune system that mediates tolerance versus allergies. This review focuses on the research over the recent 10 years regarding the potential maternal factors that influence offspring allergies with a view to food allergy, a potentially life-threatening cause of anaphylaxis. The role of breast milk, maternal diet, maternal antibodies, and microbiota that have been suggested as key maternal factors regulating offspring allergies are discussed here. We also suggest future research area to expand our knowledge of maternal-offspring interactions on the pathogenesis of food allergy.

Maternal and Infant Dietary Patterns Are Not Related to Food Allergy Risk in Singapore Children: GUSTO Cohort Study

BACKGROUND

We previously reported that delayed allergenic food introduction in infancy did not increase food allergy risk until age 4 y within our prospective cohort. However, it remains unclear whether other aspects of maternal or infant diet play roles in the development of childhood food allergy.

OBJECTIVES

We examined the relationship between maternal pregnancy and infant dietary patterns and the development of food allergies until age 8 y.

METHODS

Among 1152 Singapore Growing Up in Singapore Towards healthy Outcomes study mother-infant dyads, the infant's diet was ascertained using food frequency questionnaires at 18 mo. Maternal dietary patterns during pregnancy were derived from 24-h diet recalls. Food allergy was determined through interviewer-administered questionnaires at regular time points from infancy to age 8 y and defined as a positive history of allergic reactions, alongside skin prick tests at 18 mo, 3, 5, and 8 y.

RESULTS

Food allergy prevalence was 2.5% (22/883) at 12 mo and generally decreased over time by 8 y (1.9%; 14/736). Higher maternal dietary quality was associated with increased risk of food allergy (P ≤ 0.016); however, odds ratios were modest. Offspring food allergy risk ≤8 y showed no associations with measures of infant diet including timing of solids/food introduction (adjusted odds ratio [aOR]: 0.90; 95% confidence interval [CI]: 0.42, 1.92), infant's diet quality (aOR: 0.93; 95% CI: 0.88, 0.99) or diet diversity (aOR: 0.84; 95% CI: 0.6, 1.19). Most infants (89%) were first introduced to cow milk protein within the first month of life, while egg and peanut introduction were delayed (58.3% introduced by mean age 8.8 mo and 59.8% by mean age 18.1 mo, respectively).

CONCLUSIONS

Apart from maternal diet quality showing a modest association, infant's allergenic food introduction, diet quality, and dietary diversity were not associated with food allergy development in this Asian pediatric population. Interventional studies are needed to evaluate the efficacy of these approaches to food allergy prevention across different populations.

Primary, secondary and tertiary prevention of food allergy: current practices and future directions

The incidence of food allergies has risen around the globe, and experts have been exploring methods of preventing such allergies in young children to ease the burden of disease and reduce the morbidity and mortality caused by anaphylaxis to food allergens. Such preventative measures can be categorised as primary, secondary and tertiary prevention, which are discussed in detail in this review. Primary prevention is defined as the prevention of becoming sensitised towards specific allergens. The evidence suggests that avoiding common allergenic foods during pregnancy and breastfeeding is not protective against food allergies, and guidelines recommend weaning from 4 to 6 months of age, with recent studies supporting the early introduction of peanuts at 4 months to prevent peanut allergy. Secondary prevention targets patients who are already sensitised and aims to halt the progression of sensitisation, with evidence for high rates of success and safety in trials of early introduction to milk and peanuts using oral immunotherapy in sensitised infants. Tertiary allergy prevention focuses on reducing the risk of a patient having anaphylaxis, with oral immunotherapy being the most common method of promoting tolerance in allergic children. Several studies have demonstrated successful reintroduction for milk, egg and peanut; however, no such guidelines are recommended for other foods. Finally, dietary advancement therapy in the form of milk and egg ladders has been employed as a method of primary, secondary and tertiary prevention of allergies, particularly in Ireland, the UK and Canada.

Maternal Diet and Infant Risk of Eczema and Food Allergy: A Systematic Review

A significant portion of the pediatric population is affected by allergy diseases, which have become a worldwide public health concern. Could maternal diet during pregnancy or breastfeeding influence allergy outcomes in offspring? If this cause-and-effect relationship exists, it will be simpler to design prevention strategies to reduce the incidence of allergic disorders in children, reduce costs to the public health system and to parents, and improve the quality of life of allergic children and their parents. In this systematic review, we will visit the literature from January 2019 to December 2022 to see if any relationship was found between maternal nutrition and its consequences on children's allergy occurrence. We will focus only on food allergy and eczema outcomes in the offspring. Also, we will summarize what was found to be protective or nonprotective to better control the outcomes if applied in the future.

Maternal dietary patterns during pregnancy and the risk of infantile eczema during the first year of life: a cohort study in northeast China

BACKGROUND

There are few studies on the relationship between diet during pregnancy and infantile eczema and the conclusions are inconsistent. The aim of the present study was to explore the impact of dietary patterns during pregnancy on infantile eczema.

METHODS

A total of 495 mother-child pairs from a prospective cohort in Shenyang, China was recruited. Information on maternal dietary intake during pregnancy was assessed with a validated self-administered food frequency questionnaire. The data of infantile eczema was assessed using a structured questionnaire. Factor analysis to derive dietary patterns. The relationship between the dietary pattern and infantile eczema was examined by the logistic regression analysis.

RESULTS

The cumulative incidence of eczema in 6 months and 12 months in northeast China was 45.7% and 57.8%, respectively. Three dietary patterns were identified. There was a tendency for an expose-response relationship between the maternal high-protein dietary pattern during pregnancy and the risk of infantile eczema within 12 months (P for trend = 0.023): the adjusted odds ratio (95% confidence interval) in the Q1, Q2, Q3, Q4 were 1.00 (reference), 1.63 (0.96-2.76), 1.81 (1.06-3.06), and 1.87 (1.09-3.20), respectively. No association between Western and plant-based patterns during pregnancy and infantile eczema within 12 months was found. Infantile eczema within 6 months was not associated with any of the three dietary patterns.

CONCLUSION

The maternal high-protein pattern during pregnancy may be a risk factor for infantile eczema during the first year of life.

Prevention of food allergy in infancy: the role of maternal interventions and exposures during pregnancy and lactation

There is increased focus on the role of maternal interventions in the prevention of food allergy in infancy. There is no role for maternal dietary modifications during pregnancy or lactation, such as allergen avoidance, as a means of infant allergy prevention. Although exclusive breastfeeding is the recommended infant nutrition source globally, the effect of breastfeeding on infant allergy prevention remains unclear. There is emerging evidence that irregular cow's milk exposure (ie, infrequent formula supplementation) might increase the risk of cow's milk allergy. Although further studies are required, there is also emerging evidence that maternal peanut ingestion during breastfeeding along with early peanut introduction in infancy might have a preventive role. The effect of maternal dietary supplementation with vitamin D, omega-3, and prebiotics or probiotics remains unclear.

PrEggNut Study: protocol for a randomised controlled trial investigating the effect of a maternal diet rich in eggs and peanuts from <23 weeks' gestation during pregnancy to 4 months' lactation on infant IgE-mediated egg and peanut allergy outcomes

INTRODUCTION

Clinical studies supported by immunological data indicate early life intervention strategies to be promising in reducing the growing global burden of food allergies. The events that predispose to food allergy, including the induction of allergen-specific immune responses, appear to be initiated early in development. Early exposure to food allergens in utero and via breast milk is likely to be important in initiating oral tolerance. We aim to determine the effectiveness of higher maternal food allergen consumption during pregnancy and lactation on infant food allergy outcomes.

METHODS AND ANALYSIS

This is a multisite, parallel, two-arm (1:1 allocation), single-blinded (outcome assessors, statistical analyst and investigators), randomised controlled trial. Pregnant women (<23 weeks' gestation) whose (unborn) infants have at least two biological family members (mother, father or siblings) with medically diagnosed allergic disease are eligible to participate. After obtaining written informed consent, pregnant women are randomised to either a high egg and peanut diet (at least 6 eggs and 60 peanuts per week) or standard (low) egg and peanut diet (no more than 3 eggs and 30 peanuts per week). The women are asked to follow their allocated diet from <23 weeks' gestation to 4 months' lactation. The primary outcome is food challenge proven IgE-mediated egg and/or peanut allergy in the infants at 12 months of age. Key secondary outcomes include infant sensitisation to egg and/or peanut and infant eczema. Our target sample size is 2136 women. Analyses will be performed on an intention-to-treat basis according to a pre-specified statistical analysis plan.

ETHICS AND DISSEMINATION

Ethical approval has been granted from the Women's and Children's Health Network Human Research Ethics Committee (approval number HREC/18/WCHN/42). Trial results will be presented at scientific conferences and published in peer-reviewed journals.

TRIAL REGISTRATION NUMBER

Australian New Zealand Clinical Trials Registry ACTRN12618000937213.

Maternal Influences and Intervention Strategies on the Development of Food Allergy in Offspring

Food allergies and other immune-mediated diseases have become serious health concerns amongst infants and children in developed and developing countries. The absence of available cures limits disease management to allergen avoidance and symptomatic treatments. Research has suggested that the presence of maternal food allergies may expose the offspring to genetic predisposition, making them more susceptible to allergen sensitization. The following review has focused on epidemiologic studies regarding maternal influences of proneness to develop food allergy in offspring. The search strategy was "food allergy OR maternal effects OR offspring OR prevention". A systematically search from PubMed/MEDLINE, Science Direct and Google Scholar was conducted. Specifically, it discussed the effects of maternal immunity, microbiota, breastfeeding, genotype and allergy exposure on the development of food allergy in offspring. In addition, several commonly utilized prenatal and postpartum strategies to reduce food allergy proneness were presented, including early diagnosis of high-risk infants and various dietary interventions.

Maternal Dietary Protein Patterns During Pregnancy and the Risk of Infant Eczema: A Cohort Study

Background: Previous studies have suggested that maternal dietary protein was associated with allergic diseases in offspring, but few studies have evaluated the influence of dietary protein patterns. This study aimed to explore the prospective association between maternal dietary protein patterns during pregnancy and the risk of infant eczema.

Methods: A total of 713 mother-child pairs from a prospective cohort in Guangzhou, China were recruited. Maternal dietary protein was estimated using a validated face-to-face food frequency questionnaire at 20–28 weeks' gestation from 2017 to 2018. Dietary protein patterns were calculated based on the sources of protein. The data of infant eczema was assessed at 6 months of age using the symptom questionnaire of eczema. Logistic regression was carried out to examine the associations between maternal dietary protein patterns and infant eczema.

Results: The cumulative incidence of infant eczema at 6 months of age was 51.19%. Mothers of infants with eczema consumed more protein from poultry source during pregnancy than mothers of infants without eczema, while no statistical differences were observed in maternal intakes of protein from cereals and tubers, vegetables, fruits, red meat, fish and seafood, eggs, dairy, soybean, and nuts and seeds. Four dietary protein patterns were identified and termed poultry, plant, dairy and eggs, and red meat and fish. The cumulative incidence of eczema was 61.2, 45.8, 48.0, 51.4% for these four patterns, respectively. Compared to the poultry dietary pattern, the plant pattern and the dairy and eggs pattern were associated with a reduced risk of infant eczema, and the adjusted odds ratios (95% confidence interval) were 0.572 (0.330–0.992), 0.478 (0.274–0.837), respectively. No such association was observed for the red meat and fish dietary protein pattern.

Conclusion: This is the first study that focused on the association between maternal dietary protein during pregnancy from a whole-diet perspective and infant eczema. Compared with the poultry dietary protein pattern, the maternal plant pattern and the dairy and eggs pattern during pregnancy were associated with a reduced risk of infant eczema.

Immunologic components in human milk and allergic diseases with focus on food allergy

Human milk contains a wide range of immunomodulatory factors, including immunoglobulins, human milk oligosaccharides, cytokines, microbiome, innate factors and food antigens. Maternal diet can influence the content of human milk as it is well-established that dietary antigens can be secreted in human milk after maternal consumption, but whether these dietary antigens promote tolerance or sensitization in the infant is a subject of debate. This review summarizes the current literature on these immunologically active factors in human milk, including the microbiome, innate factors, and maternal diet-derived dietary antigens in the context of development of allergic diseases, with the focus on food allergy.

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.

A Consensus Approach to the Primary Prevention of Food Allergy Through Nutrition: Guidance from the American Academy of Allergy, Asthma, and Immunology; American College of Allergy, Asthma, and Immunology; and the Canadian Society for Allergy and Clinical Immunology

Recently published data from high-impact randomized controlled trials indicate the strong potential of strategies to prevent the development of food allergy in high-risk individuals, but guidance in the United States at present is limited to a policy for only the prevention of peanut allergy, despite other data being available and several other countries advocating early egg and peanut introduction. Eczema is considered the highest risk factor for developing IgE-mediated food allergy, but children without risk factors still develop food allergy. To prevent peanut and/or egg allergy, both peanut and egg should be introduced around 6 months of life, but not before 4 months. Screening before introduction is not required, but may be preferred by some families. Other allergens should be introduced around this time as well. Upon introducing complementary foods, infants should be fed a diverse diet, because this may help foster prevention of food allergy. There is no protective benefit from the use of hydrolyzed formula in the first year of life against food allergy or food sensitization. Maternal exclusion of common allergens during pregnancy and/or lactation as a means to prevent food allergy is not recommended. Although exclusive breast-feeding is universally recommended for all mothers, there is no specific association between exclusive breast-feeding and the primary prevention of any specific food allergy.

Current Insights on Early Life Nutrition and Prevention of Allergy

The incidence of allergic diseases in childhood appears to have significantly increased over the last decades. Since environmental factors, including diet, have been thought to play a significant role in the development of these diseases, there is great interest in identifying prevention strategies related to early nutritional interventions. Breastfeeding is critical for the immune development of newborns and infants through immune-modulating properties and it impacts the establishment of a healthy gut microbiota. However, the evidence for a protective role of breastfeeding against the development of food allergy in childhood is controversial, and there is little evidence to support the benefits of an antigen avoidance diet during lactation. Although it is not possible to draw a definitive conclusion about the protective role of breast milk against allergic diseases, exclusive breastfeeding is still recommended throughout the first 6 months of life due to associated health benefits. Furthermore, recommendations regarding complementary feeding in infancy have been significantly modified over the last few decades. Several studies have shown that delayed exposure to allergenic foods does not have a role in allergy prevention and recent guidelines recommend against delaying the introduction of complementary foods after 6 months of age, both in high- and low-risk infants. However, trials investigating this dietary approach have reported equivocal results so far. This review summarizes the available high-quality evidence regarding the efficacy of the principal dietary interventions proposed in early life to prevent allergic diseases in children.

Influences of Maternal Factors Over Offspring Allergies and the Application for Food Allergy

The prevalence of food allergy has been steadily rising worldwide with the highest incidence noted among younger children, and increasingly recognized as a growing public concern. The first known ingestion of foods often causes allergic reaction, suggesting that sensitization of offspring with food allergens may occur during pregnancy and/or through breastfeeding. This creates a milieu that shapes the neonatal immune responses to these allergens. However, the effects of maternal allergen exposure and maternal sensitization with allergens on development of allergies in offspring remain controversial. This review discusses recent advances from human data in our understanding of how maternal factors, namely, food allergens, allergen-specific immunoglobulins, cytokines, genetics, and environmental factors transferred during pregnancy or breastfeeding influence offspring allergies and how such effects may be applicable to food allergy. Based on information obtained from mouse models of asthma and food allergy, the review also dissects the mechanisms by which maternal factors, including the impact of immune complexes, transforming growth factor-β, vitamin A, and regulatory T-cell responses, contribute to the induction of neonatal tolerance vs. development of allergic responses to maternally transferred allergens.

It's Not Mom's Fault: Prenatal and Early Life Exposures that Do and Do Not Contribute to Food Allergy Development

Thus far, the most effective strategy for the prevention of food allergy is early introduction of allergenic solids to at-risk infants. Early skin moisturization may have a role in food allergy prevention. There is insufficient evidence for hydrolyzed formula as a means of allergy prevention. Studies on vitamin D, omega 3, and probiotic supplementation; breastfeeding; early infant dietary diversity; and maternal peanut ingestion during pregnancy and breastfeeding are inconsistent.

Immunomodulatory effects of breast milk on food allergy

OBJECTIVE

To summarize the literature on immunomodulatory effects of breast milk on sensitization and possible mechanisms of action.

DATA SOURCES

Animal and human studies in PubMed that assessed breastfeeding or breast milk composition in food allergy.

STUDY SELECTIONS

All recent studies and some older key publications focusing on this topic.

RESULTS

Human milk composition is highly variable among mothers, which can affect the developing infant immune system. Human milk also affects the infant gut microbiome, which is associated with food allergy. High levels of human milk immune factors (IgA, cytokines, oligosaccharides) are associated with reduced risk of food allergy in the infant; it remains uncertain whether these are directly protective or biomarkers of transferred protection. Animal studies highlight potential mechanisms of protection provided by antigens, transforming growth factor β, and immunocomplexes, yet their relevance is poorly understood in humans. The role of food antigens in human milk in initial sensitization or tolerance induction is unclear.

CONCLUSION

The protection against allergy development provided by human milk may be attributable to the effect on the infant gut microbiome or direct effects on immune system. Studies evaluating the effect of breastfeeding and human milk composition on food allergy are needed.

Maternal Perinatal Dietary Patterns Affect Food Allergy Development in Susceptible Infants

BACKGROUND

The increasing incidence of food allergy (FA) can be attributed to interactions between genes and the environment, but these interactions are not yet fully clear.

OBJECTIVE

We aimed to evaluate the interaction between infant genetic variations and maternal dietary patterns to identify risk factors in the development of FA.

METHODS

We used the Cohort for Childhood Origin of Asthma and allergic diseases birth cohort of 1628 infants, born between 2007 and 2015. Maternal dietary intakes were assessed at 26 weeks of pregnancy using a food frequency questionnaire and grouped according to 5 dietary patterns. Infant cord blood samples were genotyped at 12 loci.

RESULTS

Among 1628 infants, 147 (9.0%) were diagnosed with FA based on history. A maternal confectionery diet characterized by a higher intake of baked and sugary products during pregnancy was associated with a higher prevalence of FA (adjusted odds ratio [OR] = 1.517, P = .02); this dietary pattern tended to be higher in trans fat (r = 0.498, P < .001). Development of FA was associated with longer periods of breastfeeding (adjusted OR = 1.792, P = .03), and this dietary pattern was more significantly related to the development of FA in infants with the homozygous TT genotype of CD14 (rs2569190) and more than 1 copy of GSTM1 and GSTT1.

CONCLUSIONS

A maternal confectionery diet during pregnancy that majorly consists of baked and sugary products, combined with a longer ensuing period of breastfeeding, may lead to the development of FA, suggesting a harmful effect of trans fats in the infant. Polymorphisms in CD14 and GST in the infant influence FA susceptibility.

Prenatal Diet and the Development of Childhood Allergic Diseases: Food for Thought

PURPOSE OF REVIEW

The development of allergic disease is shaped by genetics and the environment, including diet. Many studies suggest a role for maternal diet during pregnancy. In this article, we discuss potential mechanisms by which specific nutrients, particular foods, and dietary patterns may influence allergic disease development and review studies examining the relationship between prenatal diet and the risk of childhood allergy.

RECENT FINDINGS

The combination of in utero exposures and genetic predisposition may contribute to the development of allergic disease by altering immune and organ development. Inflammation predominates in the first and third trimesters whereas the second trimester is characterized by anti-inflammatory and Th2 immune responses. Maternal dietary exposures during pregnancy may interact with inherited genetic risk factors influence immune system development. There are varied results regarding the impact of maternal prenatal diet on the development of childhood allergies. Well-designed randomized controlled studies are needed to clarify this area.

Childhood food allergies: An evolutionary mismatch hypothesis

For hominins living in the Paleolithic era, early food antigen exposures—in utero and throughout infancy—closely matched later exposures, and therefore immune system tolerance mechanisms evolved under the expectation of this condition being met. This predicts that the degree of mismatch between early and downstream food antigen exposures is a key variable underlying the development of childhood food allergies. Three historical periods are identified in which the degree of mismatch climbs from near zero to substantial, as we transition from one period to another. The first encompasses our long history as foragers; the second begins with the advent of farming and the third spans only the most recent two or three decades, and manifests from social changes driven largely by an explosion in access to information. Testable predictions are generated and evaluated in light of available evidence, and an approach for primary prevention of childhood food allergies is proposed.

Dietary intervention for preventing food allergy in children

PURPOSE OF REVIEW

In the past decade, food allergy has been increasingly recognized as an important public health issue. The role of maternal and infant diet in the development of food allergy has been a major focus of research throughout this period. Recently, research in this area has moved from observational studies to intervention trials, and the findings from these trials have started to influence infant feeding guidelines. In this article, we review recent studies of dietary interventions for preventing food allergy, summarize current knowledge and discuss future research directions.

RECENT FINDINGS

The latest result from an intervention trial shows that introduction of peanut in the first year of life reduces the risk of peanut allergy in high-risk infants. A systematic review and meta-analysis of intervention trials also suggests a protective effect of egg introduction from around 4 to 6 months of age for reducing the risk of egg allergy, with most studies conducted in high-risk infants. Despite several intervention trials involving modifications to the maternal diet, the effect of maternal diet during pregnancy and lactation in preventing food allergy remains unclear.

SUMMARY

Earlier introduction of allergenic foods is a promising intervention to reduce the risk of some food allergies in high-risk infants. Further work is needed to improve knowledge of how to prevent food allergy in the general population.

Maternal IgG immune complexes induce food allergen-specific tolerance in offspring

The role of maternal immune responses in tolerance induction is poorly understood. To study whether maternal allergen sensitization affects offspring susceptibility to food allergy, we epicutaneously sensitized female mice with ovalbumin (OVA) followed by epicutaneous sensitization and oral challenge of their offspring with OVA. Maternal OVA sensitization prevented food anaphylaxis, OVA-specific IgE production, and intestinal mast cell expansion in offspring. This protection was mediated by neonatal crystallizable fragment receptor (FcRn)-dependent transfer of maternal IgG and OVA immune complexes (IgG-IC) via breast milk and induction of allergen-specific regulatory T (T reg) cells in offspring. Breastfeeding by OVA-sensitized mothers or maternal supplementation with IgG-IC was sufficient to induce neonatal tolerance. FcRn-dependent antigen presentation by CD11c⁺ dendritic cells (DCs) in offspring was required for oral tolerance. Human breast milk containing OVA-IgG-IC induced tolerance in humanized FcRn mice. Collectively, we demonstrate that interactions of maternal IgG-IC and offspring FcRn are critical for induction of T reg cell responses and control of food-specific tolerance in neonates.

Practice Paper of the Academy of Nutrition and Dietetics: Role of the Registered Dietitian Nutritionist in the Diagnosis and Management of Food Allergies

Incidence of food allergy has increased significantly over the past decade and represents an important health issue for millions of Americans. Diagnosis of immunoglobulin E-mediated food allergies is sometimes difficult because blood and skin tests have high rates of false positives, and oral food challenges are uncommon due to the expense and potential for serious reactions. Accurate diagnosis is crucial to avoid unnecessary dietary restriction, especially in children. Because registered dietitian nutritionists often work independently, receiving referrals for dietary education and guidance for a patient who is followed by one or several other practitioners, navigating the data available and making the appropriate follow-up contact optimizes treatment. The purpose of this paper is to provide guidance to the registered dietitian nutritionists and nutrition and dietetics technician, registered on appropriate and evidence-based nutrition counseling for diagnosis and management of food allergies.

Epigenetics and allergy: from basic mechanisms to clinical applications

Allergic diseases are on the rise in the Western world and well-known allergy-protecting and -driving factors such as microbial and dietary exposure, pollution and smoking mediate their influence through alterations of the epigenetic landscape. Here, we review key facts on the involvement of epigenetic modifications in allergic diseases and summarize and critically evaluate the lessons learned from epigenome-wide association studies. We show the potential of epigenetic changes for various clinical applications: as diagnostic tools, to assess tolerance following immunotherapy or possibly predict the success of therapy at an early time point. Furthermore, new technological advances such as epigenome editing and DNAzymes will allow targeted alterations of the epigenome in the future and provide novel therapeutic tools.

The role of gene-environment interactions in the development of food allergy

The rates of IgE-mediated food allergy have increased globally, particularly in developed countries. The rising incidence is occurring more rapidly than changes to the genome sequence would allow, suggesting that environmental exposures that alter the immune response play an important role. Genetic factors may also be used to predict an increased predisposition to these environmental risk factors, giving rise to the concept of gene-environment interactions, whereby differential risk of environmental exposures is mediated through the genome. Increasing evidence also suggests a role for epigenetic mechanisms, which are sensitive to environmental exposures, in the development of food allergy. This paper discusses the current state of knowledge regarding the environmental and genetic risk factors for food allergy and how environmental exposures may interact with immune genes to modify disease risk or outcome.

Update on Early Nutrition and Food Allergy in Children

With growing evidence of an increase in the prevalence, food allergy has been emerged as a new public health problem. As treatment and management of food allergy remain challenging, more attention has been paid to the importance of prevention of food allergy. Although the exact mechanism of recent epidemic is not fully understood, it is suggested that nutritional exposure in early life may play an important role in food allergy development. The underlying hypothesis is that nutritional status or food exposure in the critical period of fetal development can affect the programming of immune system and modify the risk of immunologic reactions to foods in postnatal life. We review accumulating epidemiological studies to examine an association between nutritional exposure during pregnancy or early infancy and food allergy development in children. We also discuss recent advances in the studies of the genetic and epigenetic regulation of food allergy and evaluate the role of early nutrition in food allergy development to provide a new perspective on the prevention of food allergy.

Dietary management of peanut and tree nut allergy: what exactly should patients avoid?

Peanut and tree nut allergies are the commonest cause of life-threatening food-allergic reactions and significantly affect quality of life in children and their families. Dietary nut avoidance and provision of emergency medication is currently the mainstay of treatment. Nut avoidance has consequences on both quality of life and nutrition. We review the terminology that may cause confusion and lead to unnecessary dietary restrictions. In peanut or tree nut-allergic children, introduction of specific nuts to which the child is not allergic may improve quality of life and should be considered in patients with multiple foods allergies, vegan or ethnic-specific diets, in whom nuts are an important source of protein. Nut-allergic consumers do not just need to avoid foods containing nuts as an ingredient, but also contend with pre-packed foods which frequently have precautionary allergen labelling (PAL) referring to possible nut contamination. Although the published rate of peanut contamination in 'snack' foods with PAL (see Box ) ranges from 0.9-32.4%, peanut contamination in non-snack items with PAL is far less common. We propose that in some peanut-allergic patients (depending on history of reactivity to trace levels of peanut, reaction severity, other medical conditions, willingness to always carry adrenaline, etc.), consideration may be given to allow the consumption of non-snack foods containing PAL following discussion with the patient's (and their family's) specialist. More work is needed to provide consumers with clearer information on the risk of potential nut contamination in pre-packed food. We also draw attention to the change in legislation in December 2014 that require mandatory disclosure of allergens in non-pre-packed foods.

Role of Maternal Dietary Peanut Exposure in Development of Food Allergy and Oral Tolerance

BACKGROUND

The impact of maternal ingestion of peanut during pregnancy and lactation on an offspring's risk for peanut allergy is under debate.

OBJECTIVE

To investigate the influence of maternal dietary peanut exposure and breast milk on an offspring's allergy risk.

METHODS

Preconceptionally peanut-exposed C3H/HeJ females were either fed or not fed peanut during pregnancy and lactation. The offsprings' responses to peanut sensitization or oral tolerance induction by feeding antigen prior to immunization were assessed. We also assessed the impact of immune murine milk on tolerance induction pre- or post-weaning. For antigen uptake studies, mice were gavaged with fluorescent peanut in the presence or absence of immune murine milk; Peyer's patches were harvested for immunostaining.

RESULTS

Preconceptional peanut exposure resulted in the production of varying levels of maternal antibodies in serum (and breast milk), which were transferred to the offspring. Despite this, maternal peanut exposure either preconceptionally or during pregnancy and lactation, when compared to no maternal exposure, had no impact on peanut allergy. When offspring were fed peanut directly, dose-dependent tolerance induction, unaltered by maternal feeding of peanut, was seen. Although peanut uptake into the gut-associated lymphoid tissues was enhanced by immune milk as compared to naïve milk, tolerance induction was not affected by the co-administration of immune milk either pre- or post-weaning.

CONCLUSION

Maternal peanut exposure during pregnancy and lactation has no impact on the development of peanut allergy in the offspring. Tolerance to peanut can be induced early, even pre-weaning, by giving moderate amounts of peanut directly to the infant, and this is neither enhanced nor impaired by concurrent exposure to immune milk.

Taking the leap earlier: the timing of tolerance

PURPOSE OF REVIEW

The paradigm for the primary prevention of peanut allergy was, until recently, strict avoidance of peanut during pregnancy, infancy, and early childhood. However, in countries that had these dietary guidelines, the prevalence of peanut allergy greatly increased in contrast to low prevalence rates of peanut allergy in countries where infant diets included peanut at an early age, suggesting the hypothesis that early introduction of peanut is superior to delayed introduction of peanut as a strategy for the primary prevention of food allergy. This review examines recent high-quality studies that support this hypothesis.

RECENT FINDINGS

Publication of the Learning Early about Allergy to Peanut interventional trial showed that 17% of children avoiding peanut until 5 years of age developed peanut allergy compared with 3% of children who started eating peanut at ages of 4-11 months. Two birth cohort studies demonstrated that high maternal consumption of peanut during the pregnancy period reduced the risk of peanut allergy in offspring by 50-75%.

SUMMARY

Recent studies indicate that early introduction of peanut enhances the development of tolerance to peanut, reducing the risk of childhood peanut allergy.

Developing Primary Intervention Strategies to Prevent Allergic Disease

Allergic diseases are a major cause of morbidity in the developed world, now affecting up to 40 % of the population with no evidence that this is abating. If anything, the prevalence of early onset allergic diseases such as eczema and food allergy appears to be still increasing. This is almost certainly due to the changing modern environment and lifestyle factors, acting to promote immune dysfunction through early perturbations in immune maturation, immune tolerance and regulation. This early propensity to inflammation may also have implications for the rising risk of other inflammatory non-communicable diseases (NCDs) later in life. Identifying risk factors and pathways for preventing early onset immune disease like allergy is likely to have benefits for many aspects of human health, particularly as many NCDs share similar risk factors. This review focuses on recent advances in primary intervention strategies for promoting early immune health and preventing allergic disease, highlighting the current evidence-based guidelines where applicable and areas requiring further investigation.

Maternal diet and its influence on the development of allergic disease

The early presentation of childhood allergies and the rise in their prevalence suggest that changes in early-life exposures may increase the predisposition. Very early-life exposures may act upon the developing foetal immune system and include infection, environmental tobacco smoke, other pollutants and nutrients provided via the mother. Three nutrients have come under close scrutiny: vitamin D, omega 3 polyunsaturated fatty acids (PUFAs) and folate (or the synthetic form, folic acid). Much of the data on these nutrients are observational although some randomised, placebo-controlled trials have been conducted with omega 3 PUFAs and one with vitamin D. Some studies with omega 3 PUFA supplements in pregnancy have demonstrated immunomodulatory effects on the neonate and a reduction in risk of early sensitisation to allergens. A few studies with omega 3 polyunsaturated fatty acid supplements in pregnancy have shown a reduction in proportion of children affected by allergic symptoms (food allergy) or in symptom severity (atopic dermatitis). Observational studies investigating the association of maternal vitamin D intake or maternal or neonatal vitamin D status have been inconsistent. One randomised, controlled trial of vitamin D supplementation during pregnancy did not show any significant effect on allergic outcome in the offspring. Studies investigating the association between maternal folic acid or folate intake or maternal or neonatal folate status and offspring risk of allergic disease have been equivocal. Further evidence is required to clarify whether increased intake of these nutrients during pregnancy influences allergic disease in the offspring. In the light of current evidence, mothers should not either increase or avoid consuming these nutrients to prevent or ameliorate allergic disease in their offspring. However, these essential nutrients each have important roles in foetal development. This is reflected in current government recommendations for intake of these nutrients by pregnant women.

The Role of Skin Barrier in the Pathogenesis of Food Allergy

Food allergy is a serious public health problem with an increasing prevalence. Current management is limited to food avoidance and emergency treatment. Research into the pathogenesis of food allergy has helped to shape our understanding of how patients become sensitized to an allergen. Classically, food sensitization was thought to occur through the gastrointestinal tract, but alternative routes of sensitization are being explored, specifically through the skin. Damaged skin barrier may play a crucial role in the development of food sensitization. Better understanding of how patients initially become sensitized may help lead to the development of a safe and effective treatment for food allergies or better prevention strategies.

Eczema in early childhood, sociodemographic factors and lifestyle habits are associated with food allergy: a nested case-control study

BACKGROUND

Studies suggest an increase in food allergy prevalence over the last decade, but the contributing factors remain unknown. The aim of this study was to evaluate the association between the most common food allergies and atopic history, sociodemographic characteristics and lifestyle habits.

METHODS

We conducted a case-control study nested within the SPAACE study (Surveying Prevalence of Food Allergy in All Canadian Environments) – a cross-Canada, random telephone survey. Cases consisted of individuals with probable food allergy (self-report of convincing symptoms and/or physician diagnosis) to milk, egg, peanut, tree nut, shellfish, fish, wheat, soy, or sesame. Controls consisted of nonallergic individuals, matched for age. Cases and controls were queried on personal and family history of atopy, sociodemographic characteristics and lifestyle habits. Multivariate logistic regression was used to evaluate the association between atopy, sociodemographic characteristics and lifestyle habits with probable food allergy.

RESULTS

Between September 2010 and September 2011, 480 cases and 4,950 controls completed the questionnaire. For all 9 allergens, factors associated with a higher risk of probable allergy were as follows: (1) personal history of eczema (in the first 2 years of life), asthma or hay fever (odds ratio, OR 2.3, 95% CI 1.6-3.5; OR 2.8, 95% CI 2.2-3.6, and OR 2.3, 95% CI 1.8-3.0, respectively), (2) maternal, paternal or sibling's food allergy (OR 3.7, 95% CI 2.5-5.6; OR 3.0, 95% CI 1.8-5.1, and OR 3.1, 95% CI 2.2-4.2), (3) high household income (top 20%; OR 1.5, 95% CI 1.2-2.0). Males and older individuals were less likely to have food allergy (OR 0.7, 95% CI 0.6-0.9, and OR 0.99, 95% CI 0.99-1.00). Eczema in the first 2 years of life was the strongest risk factor for egg, peanut, tree nut and fish allergy.

CONCLUSIONS

This is the largest population-based nested case-control study exploring factors associated with food allergies. Our results reveal that, in addition to previously reported factors, eczema in the first 2 years of life is consistently associated with food allergies.

The management of peanut allergy

Peanut allergy is common and can be a cause of severe, life-threatening reactions. It is rarely outgrown like other food allergies such as egg and milk. Measures aiming to reduce its prevalence via maternal avoidance during pregnancy and lactation, or delayed introduction into the diet, have failed to show any benefit. Peanut allergy has a significant effect on the quality of life of sufferers and their families due to dietary and social restrictions, but mainly stemming from fear of accidental peanut ingestion. The current management consists of strict avoidance, education and provision of emergency medication. Families find avoidance challenging as peanut is hidden in various food products. Despite the fact that food labelling has improved, with a legal obligation to declare certain food allergens (including nuts) in prepacked products, it still causes confusion and does not extend to cross-contamination. In an effort to address issues of safety at school, a lot of work has been undertaken to better care for peanut-allergic children in that environment. This includes training of school staff on how to recognise and treat allergic reactions promptly. Recent developments in the management of peanut allergy, such as immunotherapy, have shown some promise as an active form of treatment, but larger studies are required to further investigate safety and efficacy.

Diagnosis and management of food allergies: new and emerging options: a systematic review

It is reported that 6% of children and 3% of adults have food allergies, with studies suggesting increased prevalence worldwide over the last few decades. Despite this, our diagnostic capabilities and techniques for managing patients with food allergies remain limited. We have conducted a systematic review of literature published within the last 5 years on the diagnosis and management of food allergies. While the gold standard for diagnosis remains the double-blind, placebo-controlled food challenge, this assessment is resource intensive and impractical in most clinical situations. In an effort to reduce the need for the double-blind, placebo-controlled food challenge, several risk-stratifying tests are employed, namely skin prick testing, measurement of serum-specific immunoglobulin E levels, component testing, and open food challenges. Management of food allergies typically involves allergen avoidance and carrying an epinephrine autoinjector. Clinical research trials of oral immunotherapy for some foods, including peanut, milk, egg, and peach, are under way. While oral immunotherapy is promising, its readiness for clinical application is controversial. In this review, we assess the latest studies published on the above diagnostic and management modalities, as well as novel strategies in the diagnosis and management of food allergy.

Skin exposure promotes a Th2-dependent sensitization to peanut allergens

Sensitization to foods often occurs in infancy, without a known prior oral exposure, suggesting that alternative exposure routes contribute to food allergy. Here, we tested the hypothesis that peanut proteins activate innate immune pathways in the skin that promote sensitization. We exposed mice to peanut protein extract on undamaged areas of skin and observed that repeated topical exposure to peanut allergens led to sensitization and anaphylaxis upon rechallenge. In mice, this epicutaneous peanut exposure induced sensitization to the peanut components Ara h 1 and Ara h 2, which is also observed in human peanut allergy. Both crude peanut extract and Ara h 2 alone served as adjuvants, as both induced a bystander sensitization that was similar to that induced by the atopic dermatitis-associated staphylococcal enterotoxin B. In cultured human keratinocytes and in murine skin, peanut extract directly induced cytokine expression. Moreover, topical peanut extract application induced an alteration dependent on the IL-33 receptor ST2 in skin-draining DCs, resulting in Th2 cytokine production from T cells. Together, our data support the hypothesis that peanuts are allergenic due to inherent adjuvant activity and suggest that skin exposure to food allergens contributes to sensitization to foods in early life.

Food allergy in children: what is new?

PURPOSE OF REVIEW

Food allergy affects up to 10% of preschool children, and continues to increase in prevalence in many countries, resulting in a major public health issue, with practical implications for the food industry, educational establishments and healthcare systems.

RECENT FINDINGS

The need to distinguish between food allergen sensitization and true clinical reactivity remains crucial in diagnosis, often requiring formal food challenge to avoid unnecessary dietary elimination. Epicutaneous exposure in the absence of oral tolerance induction during infancy may be an important risk factor for food allergy. Mounting evidence suggests that for milk and egg allergens, many children are able to tolerate the food when heat-modified, and that this may hasten resolution of the allergy.

SUMMARY

These developments will hopefully result in a lower adverse impact on quality of life for food-allergic individuals and their families.