Perinatal and postweaning exposure to galactooligosaccharides/inulin prebiotics induced biomarkers linked to tolerance mechanism in a mouse model of strong allergic sensitization

Microbial-Derived Tryptophan Metabolites and Their Role in Neurological Disease: Anthranilic Acid and Anthranilic Acid Derivatives

The gut microbiome provides the host access to otherwise indigestible nutrients, which are often further metabolized by the microbiome into bioactive components. The gut microbiome can also shift the balance of host-produced compounds, which may alter host health. One precursor to bioactive metabolites is the essential aromatic amino acid tryptophan. Tryptophan is mostly shunted into the kynurenine pathway but is also the primary metabolite for serotonin production and the bacterial indole pathway. Balance between tryptophan-derived bioactive metabolites is crucial for neurological homeostasis and metabolic imbalance can trigger or exacerbate neurological diseases. Alzheimer's, depression, and schizophrenia have been linked to diverging levels of tryptophan-derived anthranilic, kynurenic, and quinolinic acid. Anthranilic acid from collective microbiome metabolism plays a complex but important role in systemic host health. Although anthranilic acid and its metabolic products are of great importance for host-microbe interaction in neurological health, literature examining the mechanistic relationships between microbial production, host regulation, and neurological diseases is scarce and at times conflicting. This narrative review provides an overview of the current understanding of anthranilic acid's role in neurological health and disease, with particular focus on the contribution of the gut microbiome, the gut-brain axis, and the involvement of the three major tryptophan pathways.

The Crosstalk between the Gut Microbiota Composition and the Clinical Course of Allergic Rhinitis: The Use of Probiotics, Prebiotics and Bacterial Lysates in the Treatment of Allergic Rhinitis

Although massive progress in discovering allergic rhinitis (AR) aetiology has been made in recent years, its prevalence is still rising and it significantly impacts patients' lives. That is why further and non-conventional research elucidating the role of new factors in AR pathogenesis is needed, facilitating discoveries of new treatment approaches. One of these factors is the gut microbiota, with its specific roles in health and disease. This review presents the process of gut microbiota development, especially in early life, focusing on its impact on the immune system. It emphasizes the link between the gut microbiota composition and immune changes involved in AR development. Specifically, it elucidates the significant link between bacteria colonizing the gut and the Th1/Th2 imbalance. Probiotics, prebiotics and bacterial lysates, which are medications that restore the composition of intestinal bacteria and indirectly affect the clinical course of AR, are also discussed.

Structure and function of non-digestible carbohydrates in the gut microbiome

Together with proteins and fats, carbohydrates are one of the macronutrients in the human diet. Digestible carbohydrates, such as starch, starch-based products, sucrose, lactose, glucose and some sugar alcohols and unusual (and fairly rare) α-linked glucans, directly provide us with energy while other carbohydrates including high molecular weight polysaccharides, mainly from plant cell walls, provide us with dietary fibre. Carbohydrates which are efficiently digested in the small intestine are not available in appreciable quantities to act as substrates for gut bacteria. Some oligo- and polysaccharides, many of which are also dietary fibres, are resistant to digestion in the small intestines and enter the colon where they provide substrates for the complex bacterial ecosystem that resides there. This review will focus on these non-digestible carbohydrates (NDC) and examine their impact on the gut microbiota and their physiological impact. Of particular focus will be the potential of non-digestible carbohydrates to act as prebiotics, but the review will also evaluate direct effects of NDC on human cells and systems.

Prebiotic Supplementation During Pregnancy Modifies the Gut Microbiota and Increases Metabolites in Amniotic Fluid, Driving a Tolerogenic Environment In Utero

The gut microbiota is influenced by environmental factors such as food. Maternal diet during pregnancy modifies the gut microbiota composition and function, leading to the production of specific compounds that are transferred to the fetus and enhance the ontogeny and maturation of the immune system. Prebiotics are fermented by gut bacteria, leading to the release of short-chain fatty acids that can specifically interact with the immune system, inducing a switch toward tolerogenic populations and therefore conferring health benefits. In this study, pregnant BALB/cJRj mice were fed either a control diet or a diet enriched in prebiotics (Galacto-oligosaccharides/Inulin). We hypothesized that galacto-oligosaccharides/inulin supplementation during gestation could modify the maternal microbiota, favoring healthy immune imprinting in the fetus. Galacto-oligosaccharides/inulin supplementation during gestation increases the abundance of Bacteroidetes and decreases that of Firmicutes in the gut microbiota, leading to increased production of fecal acetate, which was found for the first time in amniotic fluid. Prebiotic supplementation increased the abundance of regulatory B and T cells in gestational tissues and in the fetus. Interestingly, these regulatory cells remained later in life. In conclusion, prebiotic supplementation during pregnancy leads to the transmission of specific microbial and immune factors from mother to child, allowing the establishment of tolerogenic immune imprinting in the fetus that may be beneficial for infant health outcomes.

Control of lymphocyte functions by gut microbiota-derived short-chain fatty acids

A mounting body of evidence indicates that dietary fiber (DF) metabolites produced by commensal bacteria play essential roles in balancing the immune system. DF, considered nonessential nutrients in the past, is now considered to be necessary to maintain adequate levels of immunity and suppress inflammatory and allergic responses. Short-chain fatty acids (SCFAs), such as acetate, propionate, and butyrate, are the major DF metabolites and mostly produced by specialized commensal bacteria that are capable of breaking down DF into simpler saccharides and further metabolizing the saccharides into SCFAs. SCFAs act on many cell types to regulate a number of important biological processes, including host metabolism, intestinal functions, and immunity system. This review specifically highlights the regulatory functions of DF and SCFAs in the immune system with a focus on major innate and adaptive lymphocytes. Current information regarding how SCFAs regulate innate lymphoid cells, T helper cells, cytotoxic T cells, and B cells and how these functions impact immunity, inflammation, and allergic responses are discussed.

Basolateral Secretion from Caco-2 Cells Pretreated with Fecal Waters from Breast Cancer Patients Affects MCF7 Cell Viability

We hypothesized that the role of microbiota in breast cancer relates to its influence on gut lipid metabolism. This was tested in an in vitro model combining MCF-7 and Caco-2 cells. A total of 32 women newly diagnosed for breast cancer before any treatment and 28 healthy women provided their stools. Bacterial DNA was amplified by qPCR targeting 16s rRNA specific to Bacteroidetes and Firmicutes phyla, Lactobacillales sp., Clostridium cluster IV, Faecalibacterium prausnitzii, Clostridium cluster XIVa, Roseburia intestinalis, Blautia sp., Lactonifactor longoviformis, Bifidobacterium sp., Coriobacteriaceae, Eggertella lenta, Escherichia, and Shigella. Fecal waters (FW) were quantified for short chain fatty acids (SCFA). Caco-2 cells grown on filter inserts were incubated apically with 10% FW for 24 h, and LXR, apolipoproteins AIV, and E gene expression were estimated by real time (RT) qPCR. Then, MCF-7 cells were incubated with the whole basolateral medium for 24 h, and their viability was estimated by 3-(4,5-Dimethyl-2-thiazolyl)-2,5-diphenyltetrazolium bromide (MTT) test. Regression models were used to determine the correlation between MCF-7 viability and bacteria relative abundance, Caco-2 cells lipid metabolism gene expression and stool composition, as well as microbiota composition and short chain fatty acids. Logistic regression models established disease odds ratios (OR) for MCF-7 viability and Caco-2 gene expression. The OR of MCF-7 viability was 1.05 (1.01–1.10) (OR (5th–95th), p = 0.04), while that of apo AIV gene expression was 0.63 (0.39–1.01), p = 0.055). Viability correlated with % Bifidobacterium sp. (21.18 ± 7.66, p = 0.008) and valerate (−2.849 ± 1.048, p = 0.009) (β ± s.d.). This study suggests that microbiota interacts with intestine cell lipid metabolism. Since these metabolites can reach breast cells by systemic circulation, we hypothesized that they may influence cancer disease.

Prebiotics: Mechanisms and Preventive Effects in Allergy

Allergic diseases now affect over 30% of individuals in many communities, particularly young children, underscoring the need for effective prevention strategies in early life. These allergic conditions have been linked to environmental and lifestyle changes driving the dysfunction of three interdependent biological systems: microbiota, epithelial barrier and immune system. While this is multifactorial, dietary changes are of particular interest in the altered establishment and maturation of the microbiome, including the associated profile of metabolites that modulate immune development and barrier function. Prebiotics are non-digestible food ingredients that beneficially influence the health of the host by 1) acting as a fermentable substrate for some specific commensal host bacteria leading to the release of short-chain fatty acids in the gut intestinal tract influencing many molecular and cellular processes; 2) acting directly on several compartments and specifically on different patterns of cells (epithelial and immune cells). Nutrients with prebiotic properties are therefore of central interest in allergy prevention for their potential to promote a more tolerogenic environment through these multiple pathways. Both observational studies and experimental models lend further credence to this hypothesis. In this review, we describe both the mechanisms and the therapeutic evidence from preclinical and clinical studies exploring the role of prebiotics in allergy prevention.

Effectiveness of an antenatal maternal supplementation with prebiotics for preventing atopic dermatitis in high-risk children (the PREGRALL study): protocol for a randomised controlled trial

INTRODUCTION

Atopic dermatitis (AD) is a chronic inflammatory disease affecting 10%-15% of children in Europe. There is a need for new primary preventive therapeutic strategies in at-risk populations. Recent research has indicated that atopic diseases are associated with a disrupted gut microbial 'balance' in early life raising the possibility that interventions which yield optimal patterns of microflora could improve host's health. Prebiotics, sugars with immunomodulatory properties that stimulate the diversity of the digestive microbiota, are ideal candidates for such research. So far, most clinical trials have focused on improving infant gut colonisation postnatally. However, prenatal life is a crucial period during which different tolerance mechanisms are put in place. We aim to determine whether antenatal prebiotics supplementation prevents AD in high-risk children.

METHODS AND ANALYSIS

This is a randomised, multicentre, double-blind, trial to evaluate the effectiveness of antenatal prebiotic maternal supplementation (galacto-oligosaccharide/inulin) in pregnant women versus placebo on the occurrence of AD at 1 year of age in at-risk children (defined as having a maternal history of atopic disease). Participating women will be randomised to daily ingestion of a prebiotics or placebo (maltodextrin) from 20 weeks' gestation until delivery. The primary outcome is the prevalence of AD at 1 year of age, using the version of the UK Working Party Diagnostic Criteria optimised for preventive studies. Key secondary endpoints are AD severity, quality of life and prebiotics tolerance. The target sample size is 376 women (188 patients per group) which will provide 80% power to detect a 33% reduction of the risk of AD in the verum group (α=0.05). The primary analysis will be based on the intention-to-treat principle.

ETHICS AND DISSEMINATION

Results will be presented in peer-reviewed journals and at international conferences. Ethics approval for the study was obtained from the institutional ethical review board of 'Comité de Protection des Personnes Sud Ouest-Outre-Mer III' of the University Hospital Centre of Bordeaux (2017/13).

TRIAL REGISTRATION NUMBER

NCT03183440; Pre-results.

Mechanisms by which gut microorganisms influence food sensitivities

Finely tuned mechanisms enable the gastrointestinal tract to break down dietary components into nutrients without mounting, in the majority of cases, a dysregulated immune or functional host response. However, adverse reactions to food have been steadily increasing, and evidence suggests that this process is environmental. Adverse food reactions can be divided according to their underlying pathophysiology into food intolerances, when, for instance, there is deficiency of a host enzyme required to digest the food component, and food sensitivities, when immune mechanisms are involved. In this Review, we discuss the clinical and experimental evidence for enteric infections and/or alterations in the gut microbiota in inciting food sensitivity. We focus on mechanisms by which microorganisms might provide direct pro-inflammatory signals to the host promoting breakdown of oral tolerance to food antigens or indirect pathways that involve the metabolism of protein antigens and other dietary components by gut microorganisms. Better understanding of these mechanisms will help in the development of preventive and therapeutic strategies for food sensitivities.

Fructooligosaccharide Inhibits the Absorption of β-conglycinin (A Major Soybean Allergen) in IPEC-J2

Dissecting the inhibited variation of allergen absorption could contribute to the development of novel therapeutic or preventive treatments for food/feed allergies. This study investigated the effects of fructooligosaccharide (FOS) on the absorption, intracellular accumulation of intact or hydrolysed β-conglycinin in porcine intestinal epithelial cells (IPEC-J2). As demonstrated by ELISA and immunoblotting, β-conglycinin was absorbed in a dose- and time-dependent manner (p < 0.05). Actually, β-conglycinin was easily transported and absorbed after enzymatic hydrolysis. Three peptides (52 kDa, 30 kDa and 25 kDa) were produced during transcellular absorption of intact or hydrolysed β-conglycinin. FOS inhibited the absorption of β-conglycinin, especially the 52 and 30 kDa peptides. The immunoreactive peptides derived from the 52, 35 or 22 kDa peptides were the substrings of the known epitopes determined by mass spectrometry and bioinformatic analyses. These results indicate that FOS can efficiently inhibit the absorption of 52 and 30 kDa peptides derived from β-conglycinin.

Fructo-Oligosaccharide Alleviates Soybean-Induced Anaphylaxis in Piglets by Modulating Gut Microbes

Soybean-induced anaphylaxis poses a severe threat to the health of humans and animals. Some commensal bacteria, such as Lactobacillus and Bifidobacteria, can prevent and treat allergic diseases. Prebiotic oligosaccharides, a food/diet additive, can enhance health and performance via modulating gut microbes and immune responses. The purpose of this study was to examine whether fructo-oligosaccharides (FOS) could alleviate soybean-induced anaphylaxis by modulating gut microbes. Piglets (21 days of age) were sensitized with a diet containing 5% soybean and 30% peeled soybean meal. The treatment with 0.6% FOS started 1 day prior to sensitization and continued everyday thereafter. Blood was collected for measurements of immune indices. The DNA samples isolated from fresh intestinal contents of the middle jejunum (M-jejunum), posterior jejunum (P-jejunum), ileum, and cecum were used for gene sequencing based on 16S rRNA. Our results showed that there was an increase of glycinin-specific IgG, β-conglycinin-specific IgG, total serum IgG and IgE, and occurrence of diarrhea in piglets sensitized with soybean antigen. There was a decrease in interleukin 4 (IL-4) and IL-10 and an increase of interferon-γ (IFN-γ) in piglets with FOS treatment, compared with the piglets without FOS treatment. Improvement of intestinal microbes was indicated mostly by the increase of Lactobacillus and Bifidobacteria in M-jejunum and the decrease of Proteobacteria in P-jejunum and ileum. The correlation analysis indicated that FOS treatment decreased those closely related to the key species of gut microbes. These results suggest that FOS can alleviate soybean antigen-induced anaphylaxis, which is associated with increased Lactobacillus and Bifidobacteria in M-jejunum and declined Proteobacteria in P-jejunum and ileum of piglets.

A Comparative Review on Microbiota Manipulation: Lessons From Fish, Plants, Livestock, and Human Research

During recent years the impact of microbial communities on the health of their host (being plants, fish, and terrestrial animals including humans) has received increasing attention. The microbiota provides the host with nutrients, induces host immune development and metabolism, and protects the host against invading pathogens (1-6). Through millions of years of co-evolution bacteria and hosts have developed intimate relationships. Microbial colonization shapes the host immune system that in turn can shape the microbial composition (7-9). However, with the large scale use of antibiotics in agriculture and human medicine over the last decades an increase of diseases associated with so-called dysbiosis has emerged. Dysbiosis refers to either a disturbed microbial composition (outgrowth of possible pathogenic species) or a disturbed interaction between bacteria and the host (10). Instead of using more antibiotics to treat dysbiosis there is a need to develop alternative strategies to combat disturbed microbial control. To this end, we can learn from nature itself. For example, the plant root (or "rhizosphere") microbiome of sugar beet contains several bacterial species that suppress the fungal root pathogen Rhizoctonia solani, an economically important fungal pathogen of this crop (11). Likewise, commensal bacteria present on healthy human skin produce antimicrobial molecules that selectively kill skin pathogen Staphylococcus aureus. Interestingly, patients with atopic dermatitis (inflammation of the skin) lacked antimicrobial peptide secreting commensal skin bacteria (12). In this review, we will give an overview of microbial manipulation in fish, plants, and terrestrial animals including humans to uncover conserved mechanisms and learn how we might restore microbial balance increasing the resilience of the host species.

A chimeric IgE that mimics IgE from patients allergic to acid-hydrolyzed wheat proteins is a novel tool for in vitro allergenicity assessment of functionalized glutens

Background

Acid-hydrolyzed wheat proteins (acid-HWPs) have been shown to provoke severe allergic reactions in Europe and Japan that are distinct from classical wheat allergies. Acid-HWPs were shown to contain neo-epitopes induced by the deamidation of gluten proteins. However, products with variable rates of deamidation can be found.

Objectives

In this work, we studied the effect of the extent of wheat proteins deamidation on its allergenicity. A recombinant chimeric IgE was produced and compared to patients’ IgE for its capacity to assess the IgE-mediated triggering potential of acid-HWPs.

Methods

Sera from acid-HWP allergic patients were analyzed via ELISA and a functional basophil assay for their IgE reactivity to wheat proteins with different deamidation levels. A chimeric mouse/human IgE (chIgE-DG1) specific for the main neo-epitope, QPEEPFPE, involved in allergy to acid-HWPs was characterized with respect to its functionality and its reactivity compared to that of patients’ IgE.

Results

Acid-HWPs with medium (30%) and high (50–60%) deamidation levels displayed a markedly stronger IgE binding and capacity to activate basophils than those of samples with weak (15%) deamidation levels. The monoclonal chIgE-DG1 allowed basophil degranulation in the presence of deamidated wheat proteins. ChIgE-DG1 was found to mimic patients’ IgE reactivity and displayed the same ability to rank acid-HWP products in a degranulation assay.

Conclusion

Increasing the deamidation level of products from 15% to 60% resulted in an approximately 2-fold increase in their antigenicity and a 100-fold increase in their eliciting potential. The chimeric ChIgE-DG1 may be a useful tool to evaluate functionalized glutens for their allergenic potential. By mimicking patient sera reactivity, chIgE-DG1 also provided data on the patients' IgE repertoire and on the functionality of certain repeated epitopes in gluten proteins.

High purity galacto-oligosaccharides enhance specific Bifidobacterium species and their metabolic activity in the mouse gut microbiome

Prebiotics are selectively fermented ingredients that result in specific changes in the composition and/or activity of the gastrointestinal microbiota, thus conferring benefit(s) upon the host health. The aim of this study was to evaluate the influence of a β(1-4)galacto-oligosaccharides (GOS) formulation consisting of 90% pure GOS (GOS90), on the composition and activity of the mouse gut microbiota. Germ-free mice were colonised with microbiota from four pathogen-free wt 129 mice donors (SPF), and stools were collected during a feeding trial in which GOS90 was delivered orally for 14 days. Pyrosequencing of 16S rDNA amplicons showed that Bifidobacterium and specific Lactobacillus, Bacteroides and Clostridiales were more prevalent in GOS90-fed mice after 14 days, although the prebiotic impact on Bifidobacterium varied among individual mice. Prebiotic feeding also resulted in decreased abundance of Bacteroidales, Helicobacter and Clostridium. High-throughput quantitative PCR showed an increased abundance of Bifidobacterium adolescentis, Bifidobacterium pseudocatenulatum, Bifidobacterium lactis and Bifidobacterium gallicum in the prebiotic-fed mice. Control female mice showed a higher diversity (phylogenetic diversity (PD) = 15.1 ± 3.4 in stools and PD = 13.0 ± 0.6 in intestinal contents) than control males (PD = 7.8 ± 1.6 in stool samples and PD = 9.5 ± 1.0 in intestinal contents). GOS90 did not modify inflammatory biomarkers (interleukin (IL)-6, IL-12, IL-1β, interferon gamma and tumour necrosis factor alpha). Decreased butyrate, acetate and lactate concentrations in stools of prebiotic fed mice suggested an increase in colonic absorption and reduced excretion. Overall, our results demonstrate that GOS90 is capable of modulating the intestinal microbiome resulting in expansion of the probiome (autochtonous commensal intestinal bacteria considered to have a beneficial influence on health).

Maternal exposure to GOS/inulin mixture prevents food allergies and promotes tolerance in offspring in mice

BACKGROUND

Food allergies affect 4-8% of children and are constantly on the rise, thus making allergies a timely issue. Most importantly, prevention strategies are nonexistent, and current therapeutic strategies have limited efficacy and need to be improved. One alternative to prevent or reduce allergies, particularly during infancy, could consist of modulating maternal immunity and microbiota using nondigestible food ingredients, such as prebiotics. For this purpose, we studied the preventive effects of prebiotics in Balb/c mothers during pregnancy and breastfeeding on food allergy development in offspring mice.

METHODS

After weaning, the offspring from mothers that were exposed to GOS/inulin mixture or fed a control diet were intraperitoneally sensitized to wheat proteins to induce a systemic allergic response and orally exposed to the same allergen. Immunological, physiological, and microbial parameters were analyzed.

RESULTS

GOS/inulin mixture diet modified the microbiota of mothers and their offspring. Offspring from mothers that received GOS/inulin prebiotics were protected against food allergies and displayed lower clinical scores, specifically of IgE and histamine levels, compared to offspring from mothers fed a control diet. Moreover, GOS/inulin supplementation for the mother resulted in stronger intestinal permeability in the offspring. Enhancement of the regulatory response to allergic inflammation and changes in the Th2/Th1 balance toward a dampened Th2 response were observed in mice from GOS/inulin mixture-exposed mothers.

CONCLUSION

The treatment of pregnant and lactating mice with nondigestible GOS/inulin prebiotics promotes a long-term protective effect against food allergies in the offspring.

Oligosaccharides in infant formula: more evidence to validate the role of prebiotics

The gastrointestinal (GI) microbiota differs between breast-fed and classic infant formula-fed infants. Breast milk is rich in prebiotic oligosaccharides (OS) and may also contain some probiotics, but scientific societies do not recommend the addition of prebiotic OS or probiotics to standard infant formula. Nevertheless, many infant formula companies often add one or the other or both. Different types of prebiotic OS are used in infant formula, including galacto-oligosaccharide, fructo-oligosaccharide, polydextrose and mixtures of these OS, but none adds human milk OS. There is evidence that the addition of prebiotics to infant formula brings the GI microbiota of formula-fed infants closer to that of breast-fed infants. Prebiotics change gut metabolic activity (by decreasing stool pH and increasing SCFA), have a bifidogenic effect and bring stool consistency and defecation frequency closer to those of breast-fed infants. Although there is only limited evidence that these changes in GI microbiota induce a significant clinical benefit for the immune system, interesting positive trends have been observed in some markers. Additionally, adverse effects are extremely seldom. Prebiotics are added to infant formula because breast milk contains human milk OS. Because most studies suggest a trend of beneficial effects and because these ingredients are very safe, prebiotics bring infant formula one step closer to the golden standard of breast milk.

Prebiotics in infant formula

The gastrointestinal microbiota of breast-fed babies differ from classic standard formula fed infants. While mother's milk is rich in prebiotic oligosaccharides and contains small amounts of probiotics, standard infant formula doesn't. Different prebiotic oligosaccharides are added to infant formula: galacto-oligosaccharides, fructo-oligosaccharide, polydextrose, and mixtures of these. There is evidence that addition of prebiotics in infant formula alters the gastrointestinal (GI) microbiota resembling that of breastfed infants. They are added to infant formula because of their presence in breast milk. Infants on these supplemented formula have a lower stool pH, a better stool consistency and frequency and a higher concentration of bifidobacteria in their intestine compared to infants on a non-supplemented standard formula. Since most studies suggest a trend for beneficial clinical effects, and since these ingredients are very safe, prebiotics bring infant formula one step closer to breastmilk, the golden standard. However, despite the fact that adverse events are rare, the evidence on prebiotics of a significant health benefit throughout the alteration of the gut microbiota is limited.

Food intolerance and allergy: increased incidence or contemporary inadequate diets?

PURPOSE OF REVIEW

The role of nutrients in the study of allergic disease has been studied for many years, but recent evidence suggests that it is the quality and variety of the whole diet which affects the development of food allergy. This review seeks to understand whether food allergy prevalence is increasing and the role of diet in the development of the disease.

RECENT FINDINGS

New data on the European and global prevalence of food allergy suggest that both reported and actual rates are increasing. Recent findings from studies in infants and children indicated that a Western diet could enhance the development of allergic disease, possibly due to an effect on the homeostasis of the gut microbiome, impacting the immune status of individuals.

SUMMARY

With overall prevalence rates for food allergy increasing, it is important to ascertain the relevance of dietary influences. Attention has shifted from single-nutrient prevention studies to evaluation of the effect of different dietary patterns on allergic outcomes. Evidence suggests that introduction of complementary foods should not be delayed, and the diversity of the diet in early life is important. The increasingly processed nature of the Western diet, in combination with influences on the gut microbiome, may contribute to the rising prevalence of allergic disease, including food allergy.