Age at introduction to complementary solid food and food allergy and sensitization: A systematic review and meta-analysis

Dietary Approaches for Complementary Feeding: The Greek Mediterranean Diet as a Model for Caregivers

BACKGROUND/OBJECTIVES

Complementary feeding (CF), is defined as the process of providing foods in addition to milk when breast milk or milk formula alone are no longer adequate to meet nutritional requirements. CF affects not only growth but also the subsequent development of the child's dietary preferences. The Mediterranean diet (MedDiet) is one of the most studied dietary patterns worldwide. The main purpose of this article is to provide practical guidance for CF to caregivers introducing the Greek MedDiet, summarizing the current different approaches. The evidence-based information provided could be used by developers to create a reliable digital app for CF based on Mediterranean foods and traditional dishes.

METHODS

An in-depth literature review of the existing guidelines and recently published research data on CF using PubMed, national recommendations, and grey literature were undertaken.

RESULTS

Practical, simple, evidence-based, comprehensive tables are presented. The tables serve as a guide to simplify the process of introducing Mediterranean foods in CF. Τhe tables consist of a total of more than 90 foods and day-to-day guidance for the first 13 weeks of CF. Furthermore, specific dietary guidance and suggestions regarding the order and content of meals during CF are given.

DISCUSSION

The tables are based on updated recommendations, summarizing the optimal feeding practices in a MedDiet-based perspective.

CONCLUSIONS

Conclusively, there are significant contradictions among different organizations that present practical issues and cause confusion among caregivers. An effort was carried out to provide practical evidence-based guidance for caregivers introducing MedDiet during CF.

Skin and oral intervention for food allergy prevention based on dual allergen exposure hypothesis

Early-onset atopic dermatitis increases an individual's risk of food allergies, suggesting that transcutaneous sensitization may occur through inflamed skin. Regarding food allergy causation, the dual allergen exposure hypothesis proposes that oral allergen exposure leads to immune tolerance, whereas allergen exposure via inflamed skin causes food allergies. This hypothesis suggests that it is important to induce oral immune tolerance and prevent allergic food sensitization through the skin. This review focuses on the breakthrough evidence based on the dual allergen exposure hypothesis that involves both skin and oral interventions for food allergy prevention.

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.

Regular consumption following early introduction of allergenic foods and aggressive treatment of eczema are necessary for preventing the development of food allergy in children

PURPOSE OF REVIEW

Over the past two decades, food allergy prevention strategies have shifted from 'delayed introduction' to 'no delayed introduction' to 'early introduction' of allergenic foods. This article reviews important research in this field published in the early 2020s to support future strategies for food allergy prevention.

RECENT FINDINGS

Recent randomized controlled trials (RCTs), systematic reviews, meta-analyses, and real-world studies have reported that early allergenic food introduction, especially peanut and egg, are effective for preventing food allergies. However, there are also reports that food-induced anaphylaxis admission rates in infants are increasing.

SUMMARY

Early allergenic food introduction by itself is not sufficient to prevent the development of food allergies. Recent RCTs (SPADE study and COMEET study) have demonstrated that continued regular cow's milk consumption after early introduction is important for preventing the onset of cow's milk allergy. Furthermore, an RCT (PACI study) reported that early and aggressive anti-inflammatory topical therapy for eczema can contribute to the prevention of egg allergy by suppressing percutaneous sensitization. Food allergies may be prevented through a combination of early food introduction, regular consumption, and active eczema treatment. Further research is needed to develop well tolerated, effective, and practical strategies to prevent food allergies.

Associations between diet diversity during infancy and atopic disease in later life: Systematic review

Background

The incidence of allergic disease remains high, and many studies have focused on the association between food diversity in infancy and allergic disease later in life, but their conclusions are still controversial.

Objective

We aimed to synthesize the literature on the association between childhood diet diversity and atopic disease.

Methods

We searched the PubMed, Cochrane Library, Embase, Scopus, VPCS, and Wanfang databases for studies about food diversity and atopic disease. Seventeen high-quality studies, 14 cohort studies, and 1 case-control study were included from 5244 studies with sample sizes ranging from 100 to 5225.

Results

All high-quality cohort studies showed that increasing food diversity in infancy can effectively prevent the occurrence of food allergies (5/5). Moderate evidence showed that increased food diversity reduced the risk of asthma (4/6), food sensitization (3/5), and atopic dermatitis (3/5). However, its effect on eczema (5), allergic rhinitis (4), and other diseases remains controversial.

Conclusions

Increasing food diversity during infancy is a potential method for preventing food allergy, asthma, atopic dermatitis, and food sensitization later in life. There is little or no comparative evidence about the protective effect of food diversity on other atopic diseases.

Introduction of allergenic food to infants and allergic and autoimmune conditions: a systematic review and meta-analysis

OBJECTIVES

To evaluate the effects of early introduction to allergenic foods compared with late introduction and its impact on food allergy, food sensitisation and autoimmune disease risk.

DESIGN AND SETTING

The systematic review was reported in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses 2020 guidelines. Four electronic databases (MEDLINE, CENTRAL, EMBASE and CINAHL) were searched from inception till 24 October 2022 using keywords and MeSH without limitations on publication's language or date. A forward and backwards citation analysis was also conducted. Risk of bias was assessed by three authors independently, in pairs using the Cochrane Risk of Bias Tool 2. Findings were narratively and quantitatively synthesised. Certainty of evidence was assessed using the Grading of Recommendations Assessment, Development and Evaluation approach.

PARTICIPANTS

Randomised controlled trials (RCTs) on allergenic food introduction prior to 12 months of age that evaluated its effect on the development of allergic and autoimmune conditions.

INTERVENTION

Early introduction to allergenic foods to infants diet.

MAIN OUTCOME MEASURES

(1) Food allergy and sensitisation with main measures including oral food challenge, specific-IgE, skin prick testing, physician assessment and parental reporting. (2) Allergic and autoimmune conditions such as asthma and eczema.

RESULTS

Of the 9060 identified records, we included 12 RCTs. We found high to moderate certainty evidence suggested that early introduction of allergen-containing foods reduces the risk of multiple food allergies (4 RCTs, 3854 participants, RR 0.49, 95% CI 0.33 to 0.74), egg (8 RCTs, 5193 participants, RR 0.58, 95% CI 0.44 to 0.78), peanut (3 RCTs, 4183 participants, RR 0.31, 95% CI 0.17 to 0.54) and atopic dermatitis or eczema (4 RCTs, 3579 participants, RR 0.88, 95% CI 0.78 to 1.00). Effects on other food allergies including milk, wheat, fish; autoimmune conditions, and food sensitisation are very uncertain and informed by low and very-low certainty evidence. No important subgroup differences were observed related to baseline risk of allergy and age at introduction. Sensitivity analyses limited to low risk of bias RCTs showed similar results.

CONCLUSIONS

This systematic review and meta-analysis shows that early introduction of allergen-containing food from 4 to 12 months of age, was associated with lower risk of multiple food allergy and eczema. Further research on other allergenic foods, and their long-term impact on food allergy and autoimmune risk is essential for enhancing our understanding on development of these conditions and guiding future clinical recommendations.

PROSPERO REGISTRATION NUMBER

CRD42022375679.

Management of Food Allergies and Food-Related Anaphylaxis

Importance

An estimated 7.6% of children and 10.8% of adults have IgE-mediated food-protein allergies in the US. IgE-mediated food allergies may cause anaphylaxis and death. A delayed, IgE-mediated allergic response to the food-carbohydrate galactose-α-1,3-galactose (alpha-gal) in mammalian meat affects an estimated 96 000 to 450 000 individuals in the US and is currently a leading cause of food-related anaphylaxis in adults.

Observations

In the US, 9 foods account for more than 90% of IgE-mediated food allergies-crustacean shellfish, dairy, peanut, tree nuts, fin fish, egg, wheat, soy, and sesame. Peanut is the leading food-related cause of fatal and near-fatal anaphylaxis in the US, followed by tree nuts and shellfish. The fatality rate from anaphylaxis due to food in the US is estimated to be 0.04 per million per year. Alpha-gal syndrome, which is associated with tick bites, is a rising cause of IgE-mediated food anaphylaxis. The seroprevalence of sensitization to alpha-gal ranges from 20% to 31% in the southeastern US. Self-injectable epinephrine is the first-line treatment for food-related anaphylaxis. The cornerstone of IgE-food allergy management is avoidance of the culprit food allergen. There are emerging immunotherapies to desensitize to one or more foods, with one current US Food and Drug Administration-approved oral immunotherapy product for treatment of peanut allergy.

Conclusions and Relevance

IgE-mediated food allergies, including delayed IgE-mediated allergic responses to red meat in alpha-gal syndrome, are common in the US, and may cause anaphylaxis and rarely, death. IgE-mediated anaphylaxis to food requires prompt treatment with epinephrine injection. Both food-protein allergy and alpha-gal syndrome management require avoiding allergenic foods, whereas alpha-gal syndrome also requires avoiding tick bites.

Timing of complementary feeding for early childhood allergy prevention: An overview of systematic reviews

OBJECTIVE

To summarise and critically appraise systematic review (SR) evidence on the effects of timing of complementary feeding (CF) on the occurrence of allergic sensitisation and disease.

DESIGN

Overview of SRs. AMSTAR-2 and ROBIS were used to assess methodological quality and risk of bias (RoB) of SRs. RoB 2 Tool was used to assess RoB of primary randomised controlled trials (RCTs) (or extracted). The certainty of evidence (CoE) was assessed using GRADE. Findings were synthesised narratively.

DATA SOURCES

MEDLINE (via PubMed and Ovid), the Cochrane Library and Web of Science Core Collection (2010 to 27 February 2023).

ELIGIBILITY CRITERIA

SRs investigating the effects of timing of CF in infants or young children (0-3 years) on risk of developing food allergy (FA), allergic sensitisation, asthma, allergic rhinitis, atopic eczema and adverse events based on RCT evidence.

RESULTS

Eleven SRs were included. Only two SRs had low RoB; common issues were failure to report on funding of primary studies and failure to provide a list of excluded trials. Common limitations of included trials were lack of blinding of outcome assessment or detailed trial preregistration, and inadequate handling of high loss to follow up. Primary study overlap was very high for specific FA and slight to moderate for FA in general and other primary outcomes. Introducing specific foods (peanut, cooked egg) early probably reduces the risk of specific FA. Evidence for other allergic outcomes was mostly very uncertain and based on few primary studies. Trials varied regarding timing of CF, nature of complementary foods and population risk, which limited comparability between SRs.

CONCLUSIONS

For developing guidelines to support decision-making on the timing of CF as a preventive strategy, early introduction of specific foods (i.e. egg and peanut) seems promising and safe, whereas more extensive research is required regarding other allergic outcomes and potential adverse events.

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.

Efficacy and safety of oral immunotherapy for peanut, cow's milk, and hen's egg allergy: A systematic review of randomized controlled trials

BACKGROUND

Oral immunotherapy (OIT) is a promising treatment for food allergies; however, safety is a concern. We synthesized evidence from the best randomized controlled trials (RCTs) on efficacy/safety of OIT for desensitization (DS) and remission (sustained unresponsiveness (SU)) in IgE mediated allergy to peanut, hen's eggs, and cow's milk. BODY: We searched Pubmed, EMBASE, and Cochrane databases (Until Oct 22) identifying 16 eligible RCTs published in English measuring food allergy by food challenge at the beginning and at the end of the study. The Cochrane Risk of Bias tool was used to assess study quality. We found 18 eligible studies. There was evidence of efficacy for DS for all allergens: peanut (RR 11.32; 95% CI 5.93, 21.60, I2 49%, 8 studies); hen's egg (RR 4.67; 2.66, 8.21, I2 0%, 5 studies); cow's milk (RR 13.98; 3.51, 55.65, I2 0%, 4 studies) and evidence for SU for peanut (RR 7.74; 2.90, 20.69, I2 0%, 3 studies) and hen's egg (RR 6.91; 1.67, 28.57, I2 0%, 2 studies). Allergic events were increased with intervention, and risk of adrenaline use increased for peanut RR 2.96; 1.63, 5.35, I2 0%, 8 studies; egg RR 1.71; 0.42, 6.92, I2 0%, 6 studies; and milk RR 8.45; 2.02, 35.27, I2 0%, 4 studies.

CONCLUSION

We found strong evidence that peanut, hen's egg, and cow's milk OIT can induce DS and some evidence for remission. There was a high risk of allergic reactions. Generalizability to the entire food allergic population is not known.

Defining the window of opportunity and target populations to prevent peanut allergy

BACKGROUND

Peanut allergy affects 1% to 2% of European children. Early introduction of peanut into the diet reduces allergy in high-risk infants.

OBJECTIVE

We aimed to determine the optimal target populations and timing of introduction of peanut products to prevent peanut allergy in the general population.

METHODS

Data from the Enquiring About Tolerance (EAT; n = 1303; normal risk; 3-year follow-up; ISRCTN14254740) and Learning Early About Peanut Allergy study (LEAP; n = 640; high risk; 5-year follow-up; NCT00329784) randomized controlled trials plus the Peanut Allergy Sensitization (PAS; n = 194; low and very high risk; 5-year follow-up) observational study were used to model the intervention in a general population. Peanut allergy was defined by blinded peanut challenge or diagnostic skin prick test result.

RESULTS

Targeting only the highest-risk infants with severe eczema reduced the population disease burden by only 4.6%. Greatest reductions in peanut allergy were seen when the intervention was targeted only to the larger but lower-risk groups. A 77% reduction in peanut allergy was estimated when peanut was introduced to the diet of all infants, at 4 months with eczema, and at 6 months without eczema. The estimated reduction in peanut allergy diminished with every month of delayed introduction. If introduction was delayed to 12 months, peanut allergy was only reduced by 33%.

CONCLUSIONS

The preventive benefit of early introduction of peanut products into the diet decreases as age at introduction increases. In countries where peanut allergy is a public health concern, health care professionals should help parents introduce peanut products into their infants' diet at 4 to 6 months of life.

Quality of systematic reviews on timing of complementary feeding for early childhood allergy prevention

BACKGROUND

Only rigorously prepared analyses can provide the highest level of evidence to inform decision-making. Several recent systematic reviews (SRs) examined the hypothesis that the early introduction of specific allergenic complementary foods (CFs) to infants may lead to a lower incidence of one or more allergic outcomes. However, the methodological rigour and quality of reporting of SRs in this area has not yet been systematically evaluated.

METHODS

We comprehensively searched PubMed, Medline (Ovid), and Web of Science Core Collection on 13th January 2022, using a pre-specified and tested search syntax for SRs with RCT evidence on the early introduction of allergenic CFs as a means for allergy prevention in infants and children. We examined the quality and risk of bias (RoB) using AMSTAR-2 and ROBIS tools, examined adherence to the Preferred Reporting Items for SRs and Meta-Analyses (PRISMA), and checked whether certainty of the evidence was assessed.

RESULTS

Twelve SRs were included. Application of both tools resulted in similar overall judgements in terms of direction and extent for nine of the 12 SRs. Nine SRs were found to be of critically low to low quality according to AMSTAR-2 and to be at high RoB according to ROBIS. One SR received a moderate quality rating (AMSTAR-2) and high RoB rating (ROBIS). However, for two SRs, judgements between AMSTAR-2 and ROBIS were at stark variance. Only two SRs fully adhered to the PRISMA checklist. Six SRs evaluated the certainty of the body of RCT evidence. Several SRs failed to consider unpublished studies either by an explicit a priori exclusion or by inadequate search strategies.

CONCLUSIONS

Well-conducted SRs are important for decision-making and informing guideline development, the quality of their methodology should therefore be considered. The methodological rigour and the reporting quality of SRs on the timing of CF for allergy prevention must be improved.

REGISTRATION

https://osf.io/7cs4b .

Introduction of Egg White and Yolk to Infant Diets and Early Childhood Atopic Dermatitis

This study investigated whether the introduction of allergenic foods in infancy is associated with atopic dermatitis (AD) in early childhood. Information regarding parental allergic histories, the introduction of six possible allergenic foods (fruits, egg white, egg yolk, fish, shellfish, and peanuts), and physician-diagnosed AD was obtained using age-specific questionnaires (0-2 years). Immunoglobulin E, specific to 20 food allergens, was also quantified at 12 months of age. Logistic regression analyses were used to determine the association between individual food introduction and the outcomes of food sensitization and AD. We found AD development by 2 years of age was significantly related to a parental history of allergy (adjusted odds ratio (aOR) = 1.29) and not being introduced to egg white and yolk during infancy (aORs = 2.27 and 1.97, respectively). Stratified analyses revealed that the introduction of both egg white and yolk was negatively associated with AD by 2 years of age, especially for those children where both parents had allergic diseases (aOR = 0.10). In summary, the introduction of egg white and yolk to an infant's diet may be a modifiable factor in reducing the risk of physician-diagnosed AD by 2 years of age, which may be particularly important for infants where both parents have allergies.

Epicutaneous Sensitization and Food Allergy: Preventive Strategies Targeting Skin Barrier Repair-Facts and Challenges

Food allergy represents a growing public health and socio-economic problem with an increasing prevalence over the last two decades. Despite its substantial impact on the quality of life, current treatment options for food allergy are limited to strict allergen avoidance and emergency management, creating an urgent need for effective preventive strategies. Advances in the understanding of the food allergy pathogenesis allow to develop more precise approaches targeting specific pathophysiological pathways. Recently, the skin has become an important target for food allergy prevention strategies, as it has been hypothesized that allergen exposure through the impaired skin barrier might induce an immune response resulting in subsequent development of food allergy. This review aims to discuss current evidence supporting this complex interplay between the skin barrier dysfunction and food allergy by highlighting the crucial role of epicutaneous sensitization in the causality pathway leading to food allergen sensitization and progression to clinical food allergy. We also summarize recently studied prophylactic and therapeutic interventions targeting the skin barrier repair as an emerging food allergy prevention strategy and discuss current evidence controversies and future challenges. Further studies are needed before these promising strategies can be routinely implemented as prevention advice for the general population.

Complementary and Allergenic Food Introduction in Infants: An Umbrella Review

BACKGROUND

Multiple systematic reviews examine the introduction of foods in relation to individual health outcomes, but the balance of harms and benefits has not been overviewed systematically.

OBJECTIVES

We aimed to perform an overview of systematic reviews on age of introduction of complementary and allergenic foods to the infant diet and long and short-term health outcomes.

DATA SOURCES

We searched Medline, Embase, Cochrane, and PubMed (July 25, 2022).

STUDY SELECTION

Included systematic reviews examining the introduction of complementary or allergenic foods before age 1. Outcomes included allergic, autoimmune, and inflammatory diseases, neurodevelopment, nutrition, and weight.

DATA EXTRACTION

Extraction and quality assessment were performed in duplicate (A Measurement Tool to Assess Systematic Reviews) and strength of evidence was assessed.

RESULTS

We screened 4015 articles and included 32 systematic reviews. There was moderate evidence that peanut and egg should be introduced from 4 to 11 months to prevent food allergy (6 of 10 reviews). Complementary food introduction was not associated with food allergy. Moderate certainty evidence suggested age of complementary food introduction was not associated with eczema. Age at introduction of gluten was not associated with celiac disease (high certainty evidence; 3 of 4 reviews). Low certainty evidence indicated that introducing solids before 4 months may increase the risk of childhood obesity, but not growth. There was insufficient evidence regarding an association between any food introduction and bone health, gastrointestinal diseases, autoimmune disorders, asthma, or allergic rhinitis.

LIMITATIONS

Gray literature was not included.

CONCLUSIONS

Current evidence supports introducing complementary foods around 6 months and allergenic foods before 11 months.

Allergy: Mechanistic insights into new methods of prevention and therapy

In the past few decades, the prevalence of allergic diseases has increased worldwide. Here, we review the etiology and pathophysiology of allergic diseases, including the role of the epithelial barrier, the immune system, climate change, and pollutants. Our current understanding of the roles of early life and infancy; diverse diet; skin, respiratory, and gut barriers; and microbiome in building immune tolerance to common environmental allergens has led to changes in prevention guidelines. Recent developments on the mechanisms involved in allergic diseases have been translated to effective treatments, particularly in the past 5 years, with additional treatments now in advanced clinical trials.

Changes in Serum Protein-Peptide Patterns in Atopic Children Allergic to Plant Storage Proteins

Next to cow's milk and eggs, plant foods, i.e., legumes, tree nuts and cereal grains, most often sensitise atopic children. Storage proteins constitutes the most relevant protein fraction of plant foods, causing primary sensitisation. They exhibit strong allergenic properties and immunogenicity. Our goal was to analyse sensitisation to 26 plant storage proteins in a group of 76 children aged 0-5 years with chronic symptoms of atopic dermatitis using Allergy Explorer ALEX2 and to discover changes in serum protein-peptide patterns in allergic patients with the use of MALDI-TOF-MS. We reported that 25% of children were allergic to 2S albumins, 19.7% to 7S globulins, 13.2% to 11S globulins and 1.3% to cereal prolamins. The most common allergenic molecules were Ara h 1 (18.4%), Ara h 2 (17.1%), Ara h 6 (15.8%) and Ara h 3 (11.8%) from peanuts, and the mean serum sIgE concentrations in allergic patients were 10.93 kUA/L, 15.353 kUA/L, 15.359 kUA/L and 9.038 kUA/L, respectively. In children allergic to storage proteins compared to the other patients (both allergic and non-allergic), the cell cycle control protein 50A, testis-expressed sequence 13B, DENN domain-containing protein 5A and SKI family transcriptional corepressor 2 were altered. Our results indicate that the IgE-mediated allergy to storage proteins is a huge problem in a group of young, atopic children, and show the potential of proteomic analysis in the prediction of primary sensitisation to plant foods. It is the next crucial step for understanding the molecular consequences of allergy to storage proteins.

Infant age at egg introduction and malnutrition‐related child growth in the United States

To evaluate the relationship between infant age of egg introduction and malnutrition‐related growth outcomes in the United States, we analysed secondary data of 1716 mother–child dyads in the Infant Feeding Practices Study II and its Year 6 Follow‐Up Study. Malnutrition‐related growth outcomes included body mass index z‐score (BMIZ), obesity (weight‐for‐height z‐score [WHZ] ≥3 or BMIZ ≥ 2), WHZ, wasting (WHZ < −2), height‐for‐age z‐score (HAZ), and stunting (HAZ < –2). Infant age at egg introduction was analysed as a continuous variable. We used generalised estimating equations to estimate the mean difference in continuous outcomes and relative risk [RR]) for binary outcomes, adjusting for related maternal and child confounders. We also explored interactions with child sex, maternal race/ethnicity, maternal educational level, ever breastfeeding, and formula feeding. In the total sample, a later infant age at egg introduction was associated with a lower mean difference in HAZ (confounder‐adjusted mean difference = −0.08, 95% confidence interval [CI]: −0.12 to −0.03 per month) and a higher risk of stunting (confounder‐adjusted RR = 1.17, 95% CI: 1.03–1.33 per month) at 6 years. The associations between infant age at egg introduction and 12‐month growth outcomes differed by child sex. Among females but not among males, later introduction of eggs was associated with a lower mean WHZ (−0.06 [−0.12 to 0.00] per month) at 12 months. Later egg introduction during infancy was associated with a lower mean HAZ and a higher risk of stunting in 6‐year‐old children. Besides this, it was associated with a lower WHZ among females at 12 months.

This secondary data analysis evaluated the relationship between infant age at egg introduction and malnutrition‐related growth outcomes among young US children within the Infant Feeding Practices Study II and its Year 6 Follow‐up Study.

In the total sample, a later infant age at egg introduction was associated with a lower mean 6‐year height‐for‐age z‐score and a higher risk of stunting at 6 years.

The associations between infant age at egg introduction and 12‐month growth outcomes differed by child sex. Later introduction of eggs was associated with a lower mean weight‐for‐height z‐score among females. However, this association was not observed among males.

Analysis of the Serum Profile of Cytokines Involved in the T-Helper Cell Type 17 Immune Response Pathway in Atopic Children with Food Allergy

The main risk factor for the development of food allergies (FAs) in children is atopic dermatitis (AD). AD is usually recognized as the Th1/Th2 paradigm of allergic disease. Recently, the Th1/Th2 paradigm in allergy and autoimmunity has been revised, including the role of the Th17 cell population and related cytokines. However, there are only a few studies that have found Th17 cytokine involvement in the allergic inflammatory response, especially with food allergens. This research aimed to analyze the serum profile of cytokines involved in the T-helper cell type 17 immune response pathway in young, atopic children with an IgE-mediated and delayed-type FA. The study involved 76 children (0−5 years old) with chronic AD. We used the Bio-Plex system to simultaneously determine the concentrations of 15 different cytokines in one experiment. In accordance with complete dermatological and allergological examination, including OFC testing and ALEX2 assays, participants were divided into 3 groups: IgE-mediated FA, delayed-type FA, and the control group. Data were analyzed using univariate statistical tests. In the IgE-mediated FA group, the circulating levels of tested cytokines had increased compared with those of other patients; however, a statistically significant difference was only obtained for IL-1beta (p < 0.05). According to the ROC curves, IL-1beta may be considered an effective predictor of IgE-mediated FA in AD children (p < 0.05; AUC = 0.67). In the delayed-type FA group, the concentration of most cytokines had slightly decreased compared to the control group. The obtained results suggest that FA influences the Th17-related cytokine profile in the serum of AD children. More advanced studies are needed to confirm the involvement of Th17 cytokines in the allergic inflammatory response and to prove their usefulness in clinical practice.

Effects of delivery mode and labor duration on the development of food sensitization in infancy

BACKGROUND

The effects of delivery mode and labor duration on the development of food sensitization (FS) in infancy remain unclear.

OBJECTIVE

To elucidate the potential effects of delivery mode and labor duration on FS development by 6 months of age.

METHODS

Using data from a randomized controlled trial of a birth cohort from 4 Japanese hospitals that assessed cow's milk allergy development by 6 months of age, we performed a nested case-control trial of 462 participants who had undergone the final assessment at 6 months of age. FS was defined as positive skin prick test reactions to hen's egg, cow's milk, wheat, or soy. For the primary outcome, we calculated the adjusted odds ratio of vaginal delivery (VD) relative to cesarean delivery for FS development by 6 months of age using a multivariable logistic regression analysis. For the secondary outcome, we compared labor durations between participants with and without FS using the Mann-Whitney U test.

RESULTS

The adjusted odds ratio of VD for FS development was 2.54 (95% confidence interval, 1.32-4.87; P = .005). The median labor duration was significantly longer in participants with FS (5.7 hours, interquartile range, 2.7-10.1) than in participants without FS (4.5 hours, 1.1-8.2) (P = .01).

CONCLUSION

VD was considerably associated with an increased risk of FS in infancy, and longer labor durations may promote FS development.

Early intervention and prevention of allergic diseases

Food allergy (FA) is now one of the most common chronic diseases of childhood often lasting throughout life and leading to significant worldwide healthcare burden. The precise mechanisms responsible for the development of this inflammatory condition are largely unknown; however, a multifactorial aetiology involving both environmental and genetic contributions is well accepted. A precise understanding of the pathogenesis of FA is an essential first step to developing comprehensive prevention strategies that could mitigate this epidemic. As it is frequently preceded by atopic dermatitis and can be prevented by early antigen introduction, the development of FA is likely facilitated by the improper initial presentation of antigen to the developing immune system. Primary oral exposure of antigens allowing for presentation via a well-developed mucosal immune system, rather than through a disrupted skin epidermal barrier, is essential to prevent FA. In this review, we present the data supporting the necessity of (1) an intact epidermal barrier to prevent epicutaneous antigen presentation, (2) the presence of specific commensal bacteria to maintain an intact mucosal immune system and (3) maternal/infant diet diversity, including vitamins and minerals, and appropriately timed allergenic food introduction to prevent FA.

Food Allergy Prevention: Early Versus Late Introduction of Food Allergens in Children

The emergence of food allergies in children is crucial for various medical fields seeking a viable strategy for allergy prevention. The most well-recognized approach adopted by numerous health care and government institutions hinges on the delay in the introduction of food allergens, which supposedly protects infants from sensitization and decreases the possibility of allergy development. However, recent experimental findings indicate that the benefits of this approach might be overestimated, as early exposure to allergenic foods has been shown to yield more advantageous outcomes. Multiple investigations on the causes of allergic diseases report that avoiding food allergies might be related to early consumption of these allergens. Alternatively, delaying the contact with allergenic nourishments, explored in contemporary research, has been proven to result in a higher prevalence of allergies among children, originating such conditions as atopic diseases and extreme sensitization to foods. The current paper compares the two prominent strategies of allergenic food introduction, gathering the most pertinent modern evidence to distinguish whether exposure to food allergens should be delayed or advanced.

Overview of oral tolerance induction for prevention of food allergy-Where are we now?

Oral tolerance induction through early introduction of allergenic food has proven effective in randomized controlled trials. This new approach to weaning has been incorporated into many national and international infants' feeding guidelines. However, there are questions that require further discussion, such as, which foods should be introduced early, should the intervention be targeted to infants at high-risk or to the general population, and what is the ideal timing for early food introduction. This review examines the extent to which recent trials address these critical questions and highlights areas where further research is required.

Breastfeeding but not Exclusively: Exploration of Chinese American Mothers' Infant Feeding Practices

BACKGROUND

Previous qualitative researchers have shown that Chinese American mothers experienced high rates of suboptimal breastfeeding, especially early introduction of other foods before the recommended 6-month period of exclusive breastfeeding.

RESEARCH AIMS

(1) To explore attitudes that Chinese American mothers have about the meaning and practice of exclusive breastfeeding; (2) to evaluate the extent of family pressure and support to maintain exclusive breastfeeding; and (3) to examine the influence of breastfeeding self-efficacy and the intention to continue exclusive breastfeeding.

METHOD

Guided by the theory of planned behavior, this descriptive cross-sectional prospective online survey was conducted with Chinese American breastfeeding mothers (N = 401). Participants' attitudes, subjective norms, and perceived behavioral control for exclusive breastfeeding behaviors were measured.

RESULTS

The M (SD) age of participants was 29.14 (SD = 6.90). Just over 50% reported receiving family support for exclusive breastfeeding. While participants had positive attitudes about exclusive breastfeeding and the value of colostrum, 64% (n = 257) had already introduced foods other than mother's own milk before their infant was 6-months old. Participants also expressed concern that their infants did not receive enough nutrition from exclusive mother's milk. Participants with more than one child had significantly greater intention to continue exclusive breastfeeding compared to participants with only one child. Perception of approval by others for exclusive breastfeeding and breastfeeding self-efficacy were significantly related to behavioral intention to continue exclusive breastfeeding.

CONCLUSION

Suboptimal infant feeding is a problem for Chinese American women and may also be a problem for mothers in other ethnic groups. We found a lack of adherence with standard recommendations for sustaining 6-months of exclusive breastfeeding.

Recipe Components and Parents' Infant and Young Child Feeding Concerns: A Mixed-Methods Study of Recipe Posts Shared in Thai Facebook Groups for Parents

Social media is increasingly becoming a significant source of information for parents, including about feeding young children. However, little attention has been given to the characteristics of recipes for infants and young children and how they interact with parental perceptions regarding food decisions shared by users on social media. Building on findings related to shared recipe components and parental food choices, between December 2019 and July 2020, this study retrospectively collected 80 shared recipes each from five Thai Facebook groups. This extraction created 379 shared recipes with 1751 peers’ commentaries on the shared recipes’ posts. The shared recipes were classified and components quantified across child age groups, then the textual contents around the reasons behind the food choices were described qualitatively. The results showed that there were differences in meal types, food ingredients, and seasoning used across child age groups. Further analysis found that food allergy awareness was one driving concern behind parental perceptions on food choices in children’s diets. These concerns resulted in delays in the introduction of animal-source foods. Moreover, peers’ commentaries on shared recipes offered a venue for exchanging experiences with food products. Because of the potential influence on parental beliefs and perceptions, further studies are required to understand the impact of existing online communities on actual feeding practices.

The evidence for interventions in early childhood allergy prevention - towards a living systematic review: protocol

Background: Research in early childhood allergy prevention (ECAP) is flourishing and new intervention strategies have proven to be promising. Due to the dynamic nature of ECAP, gaps between what is known and how guidelines inform practice are likely. A living systematic review (LSR) can narrow this gap by incorporating new evidence as it becomes available. No efficacy comparisons across various ECAP interventions for similar outcomes have been carried out. Networks of randomised clinical trials can be evaluated in the context of a network meta-analysis (NMA). We aim to establish a LSR on the efficacy and safety of any intervention investigated in randomised controlled trials (RCT) to prevent the occurrence of allergic sensitisation (AS), symptoms or diagnoses of allergic diseases in infancy and early childhood (0-3 years). Methods: A baseline SR will synthesise the evidence from existing SRs of RCTs as well as RCTs not yet considered in these. After completion of the baseline SR we propose to conduct a LSR. Using this methodology, we aim to undertake constant evidence surveillance, three-monthly search updates, and review updates every three months, should new evidence emerge. Conclusions: The ECAP evidence landscape has undergone dramatic transformations and this process is likely to continue. As a response to this, a LSR offers the potential to allow more timely synthesis of new evidence as it emerges. Long gaps between updates of SRs makes it harder for guidelines and recommendations to be up to date. Users of information, such as parents, may be confused if they encounter new evidence that is not part of a trusted guideline. A LSR approach allows us to continuously search the literature and update the evidence-base of existing ECAP interventions resulting in a decreased timespan from evidence accrual to informing clinical practice.

The evidence for interventions in early childhood allergy prevention - towards a living systematic review: protocol

Background: Research in early childhood allergy prevention (ECAP) is flourishing and new intervention strategies have proven to be promising. Due to the dynamic nature of ECAP, gaps between what is known and how guidelines inform practice are likely. A living systematic review (LSR) can narrow this gap by incorporating new evidence as it becomes available. No efficacy comparisons across various ECAP interventions for similar outcomes have been carried out. Networks of randomised clinical trials can be evaluated in the context of a network meta-analysis (NMA). We aim to establish a LSR on the efficacy and safety of any intervention investigated in randomised controlled trials (RCT) to prevent the occurrence of allergic sensitisation (AS), symptoms or diagnoses of allergic diseases in infancy and early childhood (0-3 years). Methods: A baseline SR will synthesise the evidence from existing SRs of RCTs as well as RCTs not yet considered in these. After completion of the baseline SR we propose to conduct a LSR. Using this methodology, we aim to undertake constant evidence surveillance, three-monthly search updates, and review updates every three months, should new evidence emerge. Conclusions: The ECAP evidence landscape has undergone dramatic transformations and this process is likely to continue. As a response to this, a LSR offers the potential to allow more timely synthesis of new evidence as it emerges. Long gaps between updates of SRs makes it harder for guidelines and recommendations to be up to date. Users of information, such as parents, may be confused if they encounter new evidence that is not part of a trusted guideline. A LSR approach allows us to continuously search the literature and update the evidence-base of existing ECAP interventions resulting in a decreased timespan from evidence accrual to informing clinical practice.

Incidence and timing of offspring asthma, wheeze, allergic rhinitis, atopic dermatitis, and food allergy and association with maternal history of asthma and allergic rhinitis

Background

Studying the developmental precursors of allergy may help explain the mechanisms (or etiology) of allergic disease. We studied childhood respiratory and allergic diseases in a pre-birth cohort from the United States.

Objective

We assessed the associations between maternal history of asthma and the development of respiratory and allergic diseases in offspring. We also assessed associations with maternal history of allergic rhinitis.

Methods

Maternal history of asthma and allergic rhinitis was self-reported during early pregnancy. Offspring respiratory and allergy information was obtained from electronic medical records. Adjusted Cox proportional hazard models assessed the associations between maternal history of asthma and development of respiratory and allergic diseases in the offspring up to 8 years. A similar approach was used for maternal history of allergic rhinitis.

Results

Children born to women with a history of asthma had a 77% greater risk of developing asthma, a 45% greater risk of atopic dermatitis/eczema, and a 65% greater risk of wheeze (all p < 0.01), but no significantly increased risk of allergic rhinitis or food allergies, compared to children born to women with no history of asthma. Maternal history of allergic rhinitis was not associated with any child allergy outcome, and maternal history of both asthma and allergic rhinitis was associated with child atopic dermatitis/eczema only.

Conclusions

Maternal history of asthma was significantly associated with offspring respiratory and allergic diagnoses. The association between maternal history of asthma and offspring asthma and atopic dermatitis is a novel finding. Our findings may guide physicians who counsel families with a history of maternal asthma and allergic rhinitis about their child's risk of developing respiratory and allergic diseases.

Prevention of food allergy: can we stop the rise of IgE mediated food allergies?

PURPOSE OF REVIEW

Food allergy has become more prevalent in recent decades. Without a curative treatment for food allergy, prevention is key. Can we intervene and halt the food allergy epidemic?

RECENT FINDINGS

There are three main hypotheses to explain the rise in food allergy: the dual-allergen exposure hypothesis, the hygiene hypothesis and the vitamin D hypothesis. In a recent systematic review of randomized controlled trials, only introduction of allergenic foods, namely egg and peanut, in the diet at the time of weaning and avoidance of temporary supplementation with cow's milk formula in the first few days of life showed low to moderate evidence of a preventive effect.

SUMMARY

For primary prevention, introduction of allergenic foods at the time of weaning and avoidance of temporary supplementation with cow's milk formula in the first few days of life has been recommended. Introduction of foods once allergy has been excluded may be beneficial for sensitized subjects (secondary prevention). Once food allergy has been established, it is important to minimise complications (tertiary prevention) through allergen avoidance, timely treatment of allergic reactions, control of atopic co-morbidities and dietetic and psychological support, as appropriate. Immunomodulatory treatments can potentially be disease-modifying and require further research.

Developments allergy in 2019 through the eyes of Clinical and Experimental Allergy, Part II clinical allergy

In the second of two linked articles, we describe the development in clinical as described by Clinical & Experimental Allergy and other journals in 2019. Epidemiology, clinical allergy, asthma and rhinitis are all covered. In this article, we described the development in the field of allergy as described by Clinical and Experimental Allergy in 2019. Epidemiology, clinical allergy, asthma and rhinitis are all covered.

Preventing food allergy in infancy and childhood: Systematic review of randomised controlled trials

BACKGROUND

This systematic review of ways to prevent immediate-onset/IgE-mediated food allergy will inform guidelines by the European Academy of Allergy and Immunology (EAACI).

METHODS

The GRADE approach was used. Eleven databases were searched from 1946 to October 2019 for randomized controlled trials (and large prospective cohort studies in the case of breastfeeding). The studies included heterogeneous interventions, populations, and outcomes and so were summarized narratively.

RESULTS

Forty-six studies examined interventions to reduce the risk of food allergy in infancy (up to 1 year) or early childhood. The following interventions for pregnant or breastfeeding women and/or infants may have little to no effect on preventing food allergy, but the evidence is very uncertain: dietary avoidance of food allergens, vitamin supplements, fish oil, probiotics, prebiotics, synbiotics, and emollients. Breastfeeding, hydrolyzed formulas, and avoiding cow's milk formula may not reduce the risk of cow's milk protein allergy; however, temporary supplementation with cow's milk formula in the first week of life may increase the risk of cow's milk allergy. Introducing well-cooked egg, but not pasteurized raw egg, from 4 to 6 months probably reduces the risk of hen's egg allergy. Introducing regular peanut consumption into the diet of an infant at increased risk beginning from 4 to 11 months probably results in a large reduction in peanut allergy in countries with a high prevalence. These conclusions about introducing peanut are based on moderate certainty evidence, from single trials in high-income countries.

CONCLUSIONS

Sixty percent of the included studies were published in the last 10 years, but much still remains to be understood about preventing food allergy. In particular, there is a need to validate the potential benefits of early introduction of food allergens in a wider range of populations.

Promoting Sustained and Exclusive Breastfeeding among Chinese American Pregnant Women

This study investigated prenatal goal setting and breastfeeding attitudes and intentions for 210 Chinese American pregnant women. In addition, this study assessed impact of person-centered versus factual messages on breastfeeding attitudes and intentions. While pregnant women reported receiving information about Baby-Friendly designated hospitals from healthcare providers, most received no breastfeeding information from those same providers. Although women had positive attitudes toward breastfeeding, they showed lack of knowledge about colostrum, general approval for using infant formula, as well as early introduction of complementary foods. By extension, these attitudes suggested they misunderstood the meaning of exclusive breastfeeding. No differences were observed based on parity, trimester of pregnancy, level of education or income. Person-centered and factual messages were judged as equally effective messages, but intention to breastfeed was more affected by the factual message. Reasons for this result are discussed. Healthcare providers are positioned to proactively engage in maternal preparedness for exclusive breastfeeding. These results suggested a missed opportunity for healthcare providers to communicate the value of sustained exclusive breastfeeding for the recommended first 6 months of an infant's life and underscore a need for all antenatal healthcare providers to collaboratively ensure that breastfeeding information is comprehensively provided throughout the span of antenatal care.

Predictors of Food Sensitization in Children and Adults Across Europe

BACKGROUND

The geographical variation and temporal increase in the prevalence of food sensitization (FS) suggest environmental influences.

OBJECTIVE

To investigate how environment, infant diet, and demographic characteristics, are associated with FS in children and adults, focusing on early-life exposures.

METHODS

Data on childhood and adult environmental exposures (including, among others, sibship size, day care, pets, farm environment, and smoking), infant diet (including breast-feeding and timing of introduction to infant formula and solids), and demographic characteristics were collected from 2196 school-age children and 2185 adults completing an extensive questionnaire and blood sampling in the cross-sectional pan-European EuroPrevall project. Multivariable logistic regression was applied to determine associations between the predictor variables and sensitization to foods commonly implicated in food allergy (specific IgE ≥0.35 kU_A/L). Secondary outcomes were inhalant sensitization and primary (non-cross-reactive) FS.

RESULTS

Dog ownership in early childhood was inversely associated with childhood FS (odds ratio, 0.65; 95% CI, 0.48-0.90), as was higher gestational age at delivery (odds ratio, 0.93 [95% CI, 0.87-0.99] per week increase in age). Lower age and male sex were associated with a higher prevalence of adult FS (odds ratio, 0.97 [95% CI, 0.96-0.98] per year increase in age, and 1.39 [95% CI, 1.12-1.71] for male sex). No statistically significant associations were found between other evaluated environmental determinants and childhood or adult FS, nor between infant diet and childhood FS, although early introduction of solids did show a trend toward prevention of FS.

CONCLUSIONS

Dog ownership seems to protect against childhood FS, but independent effects of other currently conceived environmental and infant dietary determinants on FS in childhood or adulthood could not be confirmed.

Nutrition in developmental age: few rules to stay healthy

The first 1000 days of life represent a critical window for infants' and children's development. Overweight and insulin resistance, at the basis of non-communicable diseases (NCDs), are linked to various risk factors that begin in childhood, including children's diet. Italian data on infants' and children's dietary habits show higher intake of proteins, simple sugars, unhealthy fats and salt than recommended, while the iron intake is below requirement. We reviewed current literature analyzing observational studies, meta-analysis, systematic review and randomized clinical trials of the last 10 years (from 2009) on nutrition in developmental age, providing some few rules to abide by. Exclusive breastfeeding is recommended by World Health Organization for the first 6 months of life and it should be continued alongside the complementary feeding period until 12 months, or even afterward. Complementary feeding should not be started before the 17th week of age with energetically adequate foods, paying attention to limit protein intake and favoring iron-rich foods. Intake of simple sugars should be limited or avoided at all; it has been demonstrated that substituting sugar-sweetened beverages with water decreases body fatness development in adolescence. Quality of the ingested fats is more important than their quantity: polyunsaturated fatty acids should be preferred. Sodium intake should be limited in the first 24 months of life, as first prevention measure of arterial hypertension later in adulthood. Healthy eating habits are the first important step toward the prevention of NCDs.

Treatment of childhood constipation: a synthesis of systematic reviews and meta-analyses

Introduction: Constipation occurs in many children and can become chronic. Many grow out of it but for one third, it continues into adulthood. For most patients, there is no identifiable organic disorder and it is classified as functional constipation.Areas covered: In 2016, treatment of childhood constipation was extensively reviewed by Rome IV. This review covers meta-analyses and evidence for treatment of paediatric constipation since 2016 and new emerging treatments.Expert opinion: Since 2016, meta-analyses conclude 1) fibre should be included in a normal diet, but further supplementation does not improve constipation; 2) probiotics may increase stool frequency in children, but evidence from larger RCTs is needed; 3) comparing laxatives, polyethylene glycol (PEG) is superior to placebo, lactulose and milk of magnesia, and 4) appendix stomas are effective and should be considered before surgery. Emerging areas of study include food intolerance, electrical stimulation and faecal microbiota transplant. For research, outcome measures need standardising to allow comparison between studies and allow meta-analyses. To assist this, validated GI instruments have been developed by Rome IV and PedsQl.

Are avoidance diets still warranted in children with atopic dermatitis?

Nearly 40% of children with moderate-to-severe atopic dermatitis (AD) have IgE-mediated food allergy (FA). This clinical observation has been extensively documented by experimental data linking skin inflammation in AD to FA, as well as by food challenges reproducing symptoms and avoidance diets improving AD. Although food avoidance may improve AD, avoidance diets do not cure AD, may even have detrimental effects such as progression to immediate-type allergy including anaphylactic reactions, and may significantly reduce the quality of life of the patient and the family. AD care should focus upon optimal medical management, rather than dietary elimination. Food allergy testing is primarily indicated when immediate-type allergic reactions are a concern. In recalcitrant AD, if food is being considered a possible chronic trigger, a limited panel of foods may be tested. An avoidance diet is only indicated in patients clearly identified as food allergic by an appropriate diagnostic food challenge, and after adequately informing the family of the limited benefits, and possible harms of an elimination diet.

Factors Influencing the Age of Complementary Feeding-A Cross-Sectional Study from Two European Countries

The timing of introducing complementary feeding affects nutritional status and children's health. The aim of this study was to determine sociodemographic and birth-related factors associated with the age of introducing complementary foods. This cross-sectional study investigated parents (n = 5815) of children aged 12-36 months from Poland (n = 4065) and Austria (n = 1750) using a single online questionnaire. During the study, detailed data about sociodemographic characteristics, variables related to pregnancy, and early feeding practices were collected. Univariate and multivariate logistic regression models were used to investigate factors associated with the introduction of complementary feeding before 4 completed months, between 4 and 6 months, and after 6 completed months separately for both countries. Complementary foods were introduced before 4 months in 3.0% of infants (2.4% in Poland and 4.3% in Austria), between 4 and 6 months in 65.0% (60.5% in Poland and 75.3% in Austria), and after 6 completed months in 32.1% of infants (37.1% in Poland and 20.4% in Austria). The factors related to earlier introduction of complementary feeding were lower maternal age (in Austria 25-29 years: aOR 2.21 (95% CI 1.06-4.65)) and education level (in Poland and Austria primary and vocational: aOR 14.49 (95% CI 3.73-56.35), aOR 2.13 (95% CI 1.10-4.11), respectively), preterm birth (in Poland and Austria: aOR 10.21 (95% CI 5.73-18.20); aOR 4.45 (95% CI 2.42-8.18), respectively), never breastfeeding (Poland: aOR 2.73 (95% CI 1.29 - 5.76)) and receiving an infant formula after hospital discharge (in both countries: aOR 3.73 (95% CI 2.06-6.75); aOR 3.65 (95% CI 1.87-7.12), respectively). These factors should be taken into account by health professionals in identifying mothers who are least likely to follow nutritional recommendations.

Timing of Food Introduction and the Risk of Food Allergy

Given that the prevalence of pediatric IgE-mediated food allergies (FA) has followed a substantive increase in recent decades, nowadays, a research challenge is to establish whether the weaning strategy can have a role in FA prevention. In recent decades, several studies have demonstrated that delayed exposure to allergenic foods did not reduce the risk of FA, leading to the publication of recent guidelines which recommend against delaying the introduction of solid foods after 4–6 months of age, both in high- and low-risk infants, in order to prevent food allergy. In the present review, focusing on cow’s milk protein, hen’s eggs, peanuts, soy, wheat and fish, we describe the current scientific evidence on the relationship between timing of these foods’ introduction in infants’ diet and allergy development.