Dietary Diversity during Early Infancy Increases Microbial Diversity and Prevents Egg Allergy in High-Risk Infants

Emerging concepts in introducing foods for food allergy prevention

PURPOSE OF REVIEW

This review focuses on the latest information regarding the role of complementary feeding practices and food allergen introduction in the prevention of food allergies.

RECENT FINDINGS

Early introduction of food allergens for food allergy prevention is recommended by food allergy prevention guidelines and is supported by the latest randomized controlled trials. Diet diversity is recommended, supported by the latest studies from Asia. A European study indicated that diet diversity after the first year of life may still be important for food allergy prevention. The latest systematic reviews indicate there may be an association between ultra-processed food intake and food allergy development. Plant based foods and fiber play an important role in modulating the gut microbiome which has been associated with reduced food allergy outcomes. However, increased intake of food allergens within a diverse diet raises questions about excessive calorie and protein intake but can be managed by focusing on infant satiety cues.

SUMMARY

The latest studies clearly indicate and further supports that introduction of food allergies should not be delayed once complementary feeding is commenced. A diverse diet is recommended to further support the prevention of food allergies.

Diversity of complementary diet and early food allergy risk

INTRODUCTION

Diet diversity (DD) in infancy may be protective for early food allergy (FA) but there is limited knowledge about how DD incorporating consumption frequency influences FA risk.

METHODS

Three measures of DD were investigated in 2060 infants at 6 and/or at 9 months of age within the NorthPop Birth Cohort Study: a weighted DD score based on intake frequency, the number of introduced foods, and the number of introduced allergenic foods. In multivariable logistic regression models based on directed acyclic graphs, associations to parentally reported physician-diagnosed FA at age 9 and 18 months were estimated, including sensitivity and stratified analyses.

RESULTS

High weighted DD scores (24-31p) at age 9 months were associated with 61% decreased odds of FA at age 18 months [OR (95% CI) = 0.39 0.18-0.88] compared with infants with the lowest DD scores (0-17p). The association remained significant after exclusion of early FA cases. Having introduced 13-14 foods at age 9 months, independent of consumption frequency, was associated with 45% decreased odds of FA [OR (95% CI) = 0.55 (0.31-0.98)] compared to having introduced 0-10 foods. When stratifying, significantly reduced odds for FA were seen for children with eczema and for children with no FA history in the family. No association was seen between DD at age 6 months and FA at age 18 months.

CONCLUSION

A diverse diet at age 9 months may prevent FA at age 18 months. Our results underscore the need for additional investigations on the impact of consumption frequency in infancy.

Maternal allergy-preventive diet index, offspring infant diet diversity, and childhood allergic diseases

BACKGROUND

Studies of childhood diet diversity and allergic disease have not examined additional associations with an offspring allergy-linked maternal diet index during pregnancy. We studied both associations in a pre-birth cohort.

METHODS

Offspring allergic disease diagnoses were obtained from electronic medical records. Maternal and infant diet were self-reported. Adjusted parametric Weibull time-to-event models assessed associations between maternal diet index, infant diet diversity and time to development of allergic rhinitis, atopic dermatitis, asthma, wheeze, IgE-mediated food allergy, and a combined outcome of any allergic disease except for wheeze.

RESULTS

Infant diet diversity at 1 year was associated with the risk of the combined outcome between 1 and 4 years of age (p = .002). While both maternal diet index and infant diet diversity at 1 year were associated with the risk of the combined outcome between 1 and 4 years of age (both p < .05), infant diet diversity at 1 year did not modify the association between maternal diet index and the risk of the combined outcome between 1 and 4 years of age (p = .5). The group with the lowest risk of the combined allergy outcome had higher maternal diet index and higher infant diet diversity.

CONCLUSIONS

The novel finding that both maternal diet index during pregnancy and infant diet diversity at 12 months are associated with the risk of a combined allergic disease outcome points to two targets for preventive interventions: maternal diet index scores during pregnancy and offspring diet diversity during infancy.

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.

Postpartum Maternal Anxiety Affects the Development of Food Allergy Through Dietary and Gut Microbial Diversity During Early Infancy

PURPOSE

We aimed to investigate the mediating factors between maternal anxiety and the development of food allergy (FA) in children until 2 years from birth.

METHODS

In this longitudinal cohort of 122 mother-child dyads from pregnancy to 24 months of age, we regularly surveyed maternal psychological states, infant feeding data, and allergic symptoms and collected stool samples at 6 months of age for microbiome analysis. Considering the temporal order of data collection, we investigated serial mediating effects and indirect effects among maternal anxiety, dietary diversity (DD), gut microbial diversity, and FA using structural equation modeling.

RESULTS

Among the 122 infants, 15 (12.3%) were diagnosed with FA. Increased maternal anxiety between 3 and 6 months after delivery was associated with a lower DD score. Infants with low DD at 4 months showed low gut microbial richness, which was associated with FA development. When the infants were grouped into 4 subtypes, using consensus clustering of 13 gut bacteria significantly associated with maternal anxiety and DD, Prevotella, Eubacterium, Clostridiales and Lachnospiraceae were more abundant in the group with lower FA occurrence.

CONCLUSIONS

Postpartum maternal anxiety, mediated by reduced DD and gut microbial diversity, may be a risk factor for the development of FA in infants during the first 2 years of life.

Feast for thought: A comprehensive review of food allergy 2021-2023

A review of the latest publications in food allergy over the past couple of years confirmed that food allergy is a major public health concern, affecting about 8% of children and 10% of adults in developed countries. The prevalence of food allergy varies around the world, with the increase being driven mainly by environmental factors, possibly together with genetic susceptibility to environmental changes. A precise diagnosis of food allergy is extremely important. Both new tests (eg, the basophil activation test) and improved optimization of information provided by existing tests (eg, the skin prick test and measurement of specific IgE level) can contribute to improving the accuracy and patients' comfort of food allergy diagnosis. Understanding the underlying immune mechanisms is fundamental to designing allergen-specific treatments that can be safe and effective in the long term. New discoveries of the immune response to food allergens, including T-cell and B-cell responses, have emerged. Novel therapeutic approaches are being trialed at various stages of development as attempts to allow for more active intervention to treat food allergy. Prevention is key to reducing the increase in prevalence. Early introduction of allergenic foods seems to be the most effective intervention, but others are being studied, and will, it is hoped, lead to modification of the epidemiologic trajectory of food allergy over time.

Immunonutrition: Diet Diversity, Gut Microbiome and Prevention of Allergic Diseases

Allergic diseases are increasing both in morbidity and mortality. Genetic, environmental, and dietary factors may all be involved in this increase. Nutrition during pregnancy, breastfeeding, and early life may play a particularly important role in preventing allergic diseases. Based on current systematic reviews, the intake of specific nutrients has failed to prevent allergic disease. Prevention strategies have shifted their focus to the overall diet which can be described using diet diversity. Infant and maternal diet diversity in pregnancy has been associated with reduced allergy outcomes in childhood. Overall, diet also seems to have a marked effect on the microbiome compared to single foods. Factors that may negate the allergy-preventative effect of overall diet diversity include the addition of emulsifiers, advanced glycation end-product content, and overuse of commercial baby foods. There is a need to perform randomized controlled trials using overall dietary intake to support international food allergy guidelines. These studies should ideally be conducted by multi-professional teams.

The future of food allergy: Challenging existing paradigms of clinical practice

The field of food allergy has seen tremendous change over the past 5-10 years with seminal studies redefining our approach to prevention and management and novel testing modalities in the horizon. Early introduction of allergenic foods is now recommended, challenging the previous paradigm of restrictive avoidance. The management of food allergy has shifted from a passive avoidance approach to active interventions that aim to provide protection from accidental exposures, decrease allergic reaction severity and improve the quality of life of food-allergic patients and their families. Additionally, novel diagnostic tools are making their way into clinical practice with the goal to reduce the need for food challenges and assist physicians in the-often complex-diagnostic process. With all the new developments and available choices for diagnosis, prevention and therapy, shared decision-making has become a key part of medical consultation, enabling patients to make the right choice for them, based on their values and preferences. Communication with patients has also become more complex over time, as patients are seeking advice online and through social media, but the information found online may be outdated, incorrect, or lacking in context. The role of the allergist has evolved to embrace all the above exciting developments and provide patients with the optimal care that fits their needs. In this review, we discuss recent developments as well as the evolution of the field of food allergy in the next decade.

Food allergy prevention: Where are we in 2023?

Food allergy prevention involves recommendations to the maternal diet during pregnancy and breast feeding, early life feeding and introduction of solid foods. Pregnant and breastfeeding women are not recommended to exclude any food allergens from their diet, but data are lacking to support active consumption of food allergens for prevention of food allergy. Breastfeeding is recommended for the many health benefits to the mother and child but has not shown any association with reduction in childhood food allergies. There is currently no recommendation regarding the use of any infant formula for allergy prevention, including the use of partially or extensively hydrolyzed formulas. Once the introduction of solid food commences, based on randomized controlled trials, it is advised to actively introduce peanuts and egg early into the infant diet and continue with consumption of these. Although there are limited data with respect to other major food allergens and whether early introduction may prevent allergy development, there is no need to delay the introduction of these allergens into the infant diet. Interpreting food allergen consumption in the context of cultural food practices has not been studied, but it makes sense to introduce the infant to family foods by 1 year of age. Consumption of foods typical of the Western diet and foods high in advanced glycation end products may be associated with an increase in food allergies. Similarly, intake of micronutrients, such as vitamin D and omega-3 fatty acids in both the maternal and infant diet, needs further clarification in the context of food allergy prevention.