Diet of lactating women and allergic reactions in their infants

Nutrition, Gut Microbiota, and Allergy Development in Infants

The process of gut microbiota development in infants is currently being challenged by numerous factors associated with the contemporary lifestyle, including diet. A thorough understanding of all aspects of microbiota development will be necessary for engineering strategies that can modulate it in a beneficial direction. The long-term consequences for human development and health of alterations in the succession pattern that forms the gut microbiota are just beginning to be explored and require much further investigation. Nevertheless, it is clear that gut microbiota development in infancy bears strong associations with the risk for allergic disease. A useful understanding of microbial succession in the gut of infants needs to reveal not only changes in taxonomic composition but also the development of functional capacities through time and how these are related to diet and various environmental factors. Metagenomic and metatranscriptomic studies have started to produce insights into the trends of functional repertoire and gene expression change within the first year after birth. This understanding is critical as during this period the most substantial development of the gut microbiota takes place and the relations between gut microbes and host immunity are established. However, further research needs to focus on the impact of diet on these changes and on how diet can be used to counteract the challenges posed by modern lifestyles to microbiota development and reduce the risk of allergic disease.

Inherent maternal type 2 immunity: Consequences for maternal and offspring health

An inherent elevation in type 2 immunity is a feature of maternal and offspring immune systems. This has diverse implications for maternal and offspring biology including influencing success of pregnancy, offspring immune development and maternal and offspring ability to control infection and diseases such as allergies. In this review we provide a broad insight into how this immunological feature of pregnancy and early life impacts both maternal and offspring biology. We also suggest how understanding of this axis of immune influence is and may be utilised to improve maternal and offspring health.

The Gut‒Breast Axis: Programming Health for Life

The gut is a pivotal organ in health and disease. The events that take place in the gut during early life contribute to the programming, shaping and tuning of distant organs, having lifelong consequences. In this context, the maternal gut plays a quintessence in programming the mammary gland to face the nutritional, microbiological, immunological, and neuroendocrine requirements of the growing infant. Subsequently, human colostrum and milk provides the infant with an impressive array of nutrients and bioactive components, including microbes, immune cells, and stem cells. Therefore, the axis linking the maternal gut, the breast, and the infant gut seems crucial for a correct infant growth and development. The aim of this article is not to perform a systematic review of the human milk components but to provide an insight of their extremely complex interactions, which render human milk a unique functional food and explain why this biological fluid still truly remains as a scientific enigma.

Breastfeeding and autoimmunity: Programing health from the beginning

Breast milk is not only a completely adapted nutrition source for the newborn but also an impressive array of immune-active molecules that afford protection against infections and shape mucosal immune responses. Decisive imprinting events might be modulated during the first months of life with potential health long-term effects, enhancing the importance of breastfeeding as a major influence on the immune system correct development and modifying disease susceptibility. The aim of this review was to clarify the link between breastfeeding and autoimmune diseases, inquiring the related mechanisms, based on data available in the literature. Being breastfed was associated with a lower incidence of diabetes, celiac disease, multiple sclerosis and asthma, explained by the protection against early infections, anti-inflammatory properties, antigen-specific tolerance induction, and regulation of infant's microbiome. The protective role of human milk in idiopathic juvenile arthritis, rheumatoid arthritis, and inflammatory bowel diseases remains controversial. On the other hand, the breastfeeding mother faces a health-challenging period in life. High levels of prolactin may lead either to the development of autoimmune diseases in susceptible mothers or exacerbations of current immune-mediated disorders. These features raise the question if mothers with autoimmune diseases, mainly systemic lupus erythematosus, should avoid breastfeeding.

Allergy prevention by breastfeeding: possible mechanisms and evidence from human cohorts

PURPOSE OF REVIEW

Allergy is a modern disease which does not seem to benefit from breast milk preventive effects. We propose that maternal milk composition has not adapted to the needs of allergy prevention because of the recent and rapid increase of allergy. Modulation of breast milk composition may be the best strategy to counteract allergy development. We will review recent advances in understanding of allergy physiopathology and how breast milk factors may be specifically appropriate to interfere with allergy development in early life.

RECENT FINDINGS

There is strong evidence both from rodent and human studies that breast milk factors may impact on parameters which are now recognized to be essential for allergy physiopathology: infant gut barrier function, microbiota metabolites production, and oral tolerance induction. Data from human cohorts support the possibility to modify breast milk composition by selected interventions and to impact health outcomes in offspring.

SUMMARY

Nutritional intervention in lactating mothers should endow breast milk with the capacity to combat allergy epidemics in addition to infectious disease.

Antibody-independent identification of bovine milk-derived peptides in breast-milk

Exclusively breast-fed infants can exhibit clear signs of IgE or non IgE-mediated cow's milk allergy. However, the definite characterization of dietary cow's milk proteins (CMP) that survive the maternal digestive tract to be absorbed into the bloodstream and secreted into breast milk remains missing. Herein, we aimed at assessing possible CMP-derived peptides in breast milk. Using high performance liquid chromatography (HPLC)-high resolution mass spectrometry (MS), we compared the peptide fraction of breast milk from 12 donors, among which 6 drank a cup of milk daily and 6 were on a strict dairy-free diet. We identified two bovine β-lactoglobulin (β-Lg, 2 out 6 samples) and one αs1-casein (1 out 6 samples) fragments in breast milk from mothers receiving a cup of bovine milk daily. These CMP-derived fragments, namely β-Lg (f42-54), (f42-57) and αs1-casein (f180-197), were absent in milk from mothers on dairy-free diet. In contrast, neither intact nor hydrolyzed β-Lg was detected by western blot and competitive ELISA in any breast milk sample. Eight additional bovine milk-derived peptides identified by software-assisted MS were most likely false positive. The results of this study demonstrate that CMP-derived peptides rather than intact CMP may sensitize or elicit allergic responses in the neonate through mother's milk. Immunologically active peptides from the maternal diet could be involved in priming the newborn's immune system, driving a tolerogenic response.

Is infant immunization by breastfeeding possible?

Breastfeeding is known as the most efficient way to prevent infectious disease in early life. Maternal anti-microbial immunoglobulins transfer through milk confers passive immunity to the breastfed child while his immune system is maturing. Maternal milk also contains bioactive factors that will stimulate this maturation. From the literature on breastfeeding prevention of immune-mediated disease and more specifically from our experiments conducted in the field of allergic disease prevention, we propose that breastfeeding may also induce antigen-specific immune responses in the breastfed child. We found that early oral antigen exposure through breast milk leads to tolerance or immune priming depending on the nature of the antigen transferred and accompanying maternal milk cofactors. Here, we will discuss our data in the light of prevention of infectious disease and will propose that possible milk transfer of microbial antigen could affect actively the immune response in breastfed children and thereby their long-term susceptibility to infectious disease. Further research in this direction may lead to novel strategies of early life vaccination, taking advantage of the possibility to stimulate antigen-specific immune responses through breast milk.

Maternal diet during pregnancy and lactation and cow's milk allergy in offspring

BACKGROUND/OBJECTIVES

Diet during pregnancy and lactation may have a role in the development of allergic diseases. There are few human studies on the topic, especially focusing on food allergies. We sought to study the associations between maternal diet during pregnancy and lactation and cow's milk allergy (CMA) in offspring.

SUBJECTS/METHODS

A population-based birth cohort with human leukocyte antigen-conferred susceptibility to type 1 diabetes was recruited in Finland between 1997 and 2004 (n=6288). Maternal diet during pregnancy and lactation was assessed by a validated, 181-item semi-quantitative food frequency questionnaire. Register-based information on diagnosed CMA was obtained from the Social Insurance Institution and completed with parental reports. The associations between maternal food consumption and CMA were assessed using logistic regression, comparing the highest and the lowest quarters to the middle half of consumption.

RESULTS

Consumption of milk products in the highest quarter during pregnancy was associated with a lower risk of CMA in offspring (odds ratio (OR) 0.56, 95% confidence interval (CI) 0.37-0.86; P<0.01). When stratified by maternal allergic rhinitis and asthma, there was evidence of an inverse association between high use of milk products and CMA in offspring of non-allergic mothers (OR 0.30, 95% CI 0.13-0.69, P<0.001). Cord blood IgA correlated positively with the consumption of milk products during pregnancy, indicating exposure to CMA and activation of antigen-specific immunity in the infant during pregnancy.

CONCLUSIONS

High maternal consumption of milk products during pregnancy may protect children from developing CMA, especially in offspring of non-allergic mothers.

Engineering the Microbiome: a Novel Approach to Immunotherapy for Allergic and Immune Diseases

The incidence of immune disorders is growing parallel with practices associated with westernization, such as dietary changes, increased use of antibiotics, or elevated rates of Cesarean section. These practices can significantly impact the gut microbiota, the collection of bacteria residing in the human gastrointestinal tract, and subsequently disrupt the delicate balance existing between commensal flora and host immune responses. Restoring this balance by modifying the microbiota has thus emerged as a promising therapeutic approach. Here, we discuss the interaction between gut commensals and immunity, along with the potential of different interventions on the microbiota as treatment for inflammatory and allergic diseases.

Nutritional approaches for the primary prevention of allergic disease: An update

The dramatic rise in early childhood allergic diseases indicates the specific vulnerability of the immune system to early life environmental changes. Dietary changes are at the centre of lifestyle changes that underpin many modern inflammatory and metabolic diseases, and therefore are an essential element of prevention strategies. Although modern dietary changes are complex and involve changing patterns of many nutrients, there is also an interest in the early life effects of specific nutrients including polyunsaturated fatty acids, oligosaccharides (soluble fibre), antioxidants, folate and other vitamins that have documented effects on immune function as well as metabolism. A better understanding of nutritional programming of immune health, nutritional epigenetics and the biological processes sensitive to nutritional exposures in early life may lead to dietary strategies that provide more tolerogenic conditions during early immune programming and reduce the burden of many inflammatory diseases, not just allergy.

Early development of the gut microbiota and immune health

In recent years, the increase in human microbiome research brought about by the rapidly evolving “omic” technologies has established that the balance among the microbial groups present in the human gut, and their multipronged interactions with the host, are crucial for health. On the other hand, epidemiological and experimental support has also grown for the ‘early programming hypothesis’, according to which factors that act in utero and early in life program the risks for adverse health outcomes later on. The microbiota of the gut develops during infancy, in close interaction with immune development, and with extensive variability across individuals. It follows that the specific process of gut colonization and the microbe-host interactions established in an individual during this period have the potential to represent main determinants of life-long propensity to immune disease. Although much remains to be learnt on the progression of events by which the gut microbiota becomes established and initiates its intimate relationships with the host, and on the long-term repercussions of this process, recent works have advanced significatively in this direction.

Respiratory allergen from house dust mite is present in human milk and primes for allergic sensitization in a mouse model of asthma

There is an urgent need to identify environmental risk and protective factors in early life for the prevention of allergy. Our study demonstrates the presence of respiratory allergen from house dust mite, Der p 1, in human breast milk. Der p 1 in milk is immunoreactive, present in similar amounts as dietary egg antigen, and can be found in breast milk from diverse regions of the world. In a mouse model of asthma, oral exposure to Der p through breast milk strongly promotes sensitization rather than protect the progeny as we reported with egg antigen. These data highlight that antigen administration to the neonate through the oral route may contribute to child allergic sensitization and have important implications for the design of studies assessing early oral antigen exposure for allergic disease prevention. The up-to-now unknown worldwide presence of respiratory allergen in maternal milk allows new interpretation and design of environmental control epidemiological studies for allergic disease prevention.

Can food allergy be prevented? The current evidence

Food allergy is a recognized public health concern, for which preventative strategies are required. Although an intervention that adequately protects against the development of food allergy has still to be identified, limited benefits have been shown for the prevention of related allergic conditions such as eczema, and to a lesser extent asthma and rhinitis; these benefits are usually limited to at-risk populations. Prevention strategies need to be tested using randomized controlled study designs that account for the numerous methodological challenges, safety concerns, and necessary ethical limitations.

Neonatal tolerance under breastfeeding influence

Diseases due to defect in tolerance induction such as allergy, celiac disease, or Type 1 Diabetes develop mostly in childhood indicating the necessity of early intervention for primary prevention. Epidemiological studies report that breastfeeding could protect from these diseases. However, data are controversial and the mechanisms unclear. Experimental data suggest that breastfeeding-induced protection might rely on tolerance induction as long as some criteria are fulfilled. Thus, the tolerogenic potential of breast milk would depend on maternal exposure to common environmental and dietary antigens and the efficiency of antigen transfer across mammary epithelium. Induction of tolerance upon breast milk-mediated antigen transfer will also depend on the presence of immunomodulatory factors in breast milk and of its impact on neonatal gut and immune system maturation. The better understanding of maternal influence on tolerance induction through breastfeeding should allow the development of new strategies to prevent immune-mediated diseases.

Oral tolerance in neonates: from basics to potential prevention of allergic disease

Oral tolerance refers to the observation that prior feeding of an antigen induces local and systemic immune tolerance to that antigen. Physiologically, this process is probably of central importance for preventing inflammatory responses to the numerous dietary and microbial antigens present in the gut. Defective oral tolerance can lead to gut inflammatory disease, food allergies, and celiac disease. In the last two cases, the diseases develop early in life, stressing the necessity of understanding how oral tolerance is set up in neonates. This article reviews the parameters that have been outlined in adult animal models as necessary for tolerance induction and assesses whether these factors operate in neonates. In addition, we highlight the factors that are specific for this period of life and discuss how they could have an impact on oral tolerance. We pay particular attention to maternal influence on early oral tolerance induction through breast-feeding and outline the major parameters that could be modified to optimize tolerance induction in early life and possibly prevent allergic diseases.

Neonatal tolerance under breastfeeding influence: the presence of allergen and transforming growth factor-beta in breast milk protects the progeny from allergic asthma

Once the umbilical cord has been cut, immunologists have often looked at the neonate as an entity that develops on its own. For years, breast milk was considered mainly as a source of nutrients for the developing child. The extensive observations that breastfeeding affords protection toward infectious diseases and could reduce by more than the half the mortality rate because of common infections have added another key role to breastfeeding. This protection relies in great part on the passive transfer through breast milk of high amounts of microbe-specific immunoglobulins that compensate for the deficiency of immunoglobulins synthesis during the first year of life. Here, we will present and discuss our data showing how breast milk can actively shape the immune response of the progeny, particularly in the context of allergic disease. Indeed, our data obtained in a mouse model suggest that the protection attributed to breastfeeding toward asthma development might rely on immune tolerance induction. For this to occur, the mother mice needed to be exposed to the allergen by aerosol or oral route during the lactation period, which resulted into the transfer of the allergen to breast milk. The presence of the allergen together with transforming growth factor-beta in breast milk was necessary and sufficient to induce the development of regulatory T lymphocytes in the progeny and their protection from asthma development. If confirmed in human beings, this study may suggest new strategies for asthma prevention such as deliberate exposure of mother to allergens during breastfeeding and qualitative modification of artificial milks.

Modified egg as a nutritional supplement during peak brain development: a new target for fortification

BACKGROUND

Though eggs have the unique capacity, like breastmilk, to concentrate essential nutrients required for early growth and brain development of offspring - i.e. n-3 PUFA, increasingly deficient and sources contaminated - cholesterol and allergy concerns often exclude them from perinatal recommendations.

OBJECTIVE

Egg's potential contribution of key nutrients required for peak brain development are re-evaluated vis-à-vis fortification, accessibility, and risks.

METHODS

Contributions of standard (USDA) and fortified (selected market-available) egg compositions to perinatal requirements for critical brain-supporting nutrients were compared to human and cow milks, and risks and recommendations evaluated.

RESULTS

Standard egg has already higher concentrations/kcal of iron, selenium, zinc, choline, vitamins B12 and E, and essential amino acids (plus taurine) than human milk. Fortified egg could further yield significant n-3 PUFA % recommendations for pregnancy-lactation (total n-3 69.6-75.0% [DRI=1400-1300 mg/day]), including DHA (120.1-129.3%, mostly approximately 80% [calculated DRI=140-130 mg/day]), plus antioxidant vitamins A (9.0-15.2%) and E (51.6-65.3%), and minerals iodine (33.6-44.5%) and selenium (33.7-39.3%); % recommendations for children (1-3 y) even more. Cholesterol, important for nerve membranes and learning, may not be generally contraindicated in childbearing-aged women (approximately 10.5% hypercholesterolemia), and early-life egg exposure may increase tolerance. Egg-inclusive perinatal nutrition programs have shown significant contributions.

CONCLUSIONS

Eggs, especially target-fortified, may provide a unique nutritional supplement for peak brain development continously during pregnancy, nursing, and infancy (from 6 months), especially vs. insufficiencies. Missing nutritional opportunities by egg exclusion vs. concerns of hypercholesterolemia or allergy could be addressed individually, rather than as general recommendations, warranting further research and targeted egg design.

Dietary approaches to the prevention of food allergy

PURPOSE OF REVIEW

The primary prevention of food allergy and atopy has become a public health priority in developed countries. Although some preventive dietary interventions have entered common practice, the level of evidence underpinning these strategies varies.

RECENT FINDINGS

Exclusive breast-feeding and delayed introduction of complementary foods from the age of 4-6 months are key strategies in primary food allergy and atopy prevention. Maternal elimination diets during pregnancy and lactation are currently not recommended. Partially and extensively hydrolyzed formulae may confer a small preventive effect in high-risk infants. Amino acid-based formula is, however, considered a treatment formula and not recommended for primary allergy prevention. The effect of prebiotic oligosaccharides and probiotic bacteria in prevention of food allergy remains unclear and requires further investigation. Maternal fish oil supplementation during pregnancy shows promise in reducing the risk of allergic sensitization in the infant, but prospective long-term data are required. Fish oil supplementation in young infants was not effective.

SUMMARY

Although there is evidence for the primary dietary prevention of eczema and possible respiratory allergies, data on food allergy prevention have, so far, remained less convincing. Further prospective research is needed to clarify the effectiveness of dietary interventions in primary food allergy prevention.

Breast milk-mediated transfer of an antigen induces tolerance and protection from allergic asthma

Allergic asthma is a chronic disease characterized by airway obstruction in response to allergen exposure. It results from an inappropriate T helper type 2 response to environmental airborne antigens and affects 300 million individuals. Its prevalence has increased markedly in recent decades, most probably as a result of changes in environmental factors. Exposure to environmental antigens during infancy is crucial to the development of asthma. Epidemiological studies on the relationship between breastfeeding and allergic diseases have reached conflicting results. Here, we have investigated whether the exposure of lactating mice to an airborne allergen affects asthma development in progeny. We found that airborne antigens were efficiently transferred from the mother to the neonate through milk and that tolerance induction did not require the transfer of immunoglobulins. Breastfeeding-induced tolerance relied on the presence of transforming growth factor (TGF)-beta during lactation, was mediated by regulatory CD4+ T lymphocytes and depended on TGF-beta signaling in T cells. In conclusion, breast milk-mediated transfer of an antigen to the neonate resulted in oral tolerance induction leading to antigen-specific protection from allergic airway disease. This study may pave the way for the design of new strategies to prevent the development of allergic diseases.

The immunological components of human milk

Breast-feeding is generally accepted as the optimal method of feeding infants. However, we have yet to fully understand the complex mixture of bioactive compounds contained in human milk. Epidemiological studies have indicated that breast-feeding is associated with health benefits in the infant for many immune-related conditions. Breast milk contains various antimicrobial substances, factors that promote immune development, constituents that promote tolerance/priming of the infant immune system, as well as anti-inflammatory components. This chapter identifies and discusses the immunological compounds in human milk and the available evidence for their effect on the immune system of the infant. Current feeding regimens recommended for infants are based primarily on the current understanding of the nutritional requirements of the neonate, but perhaps will be modified to reflect the consequences on immune function both immediate and later in life.

Oral tolerance to contact allergens: a common occurrence? A review

Experimental and clinical oral tolerance to contact allergens has been reported sporadically, most notably in respect of nickel, and is generally assumed to be an uncommon phenomenon. There has recently been increased understanding of the immunological mechanisms inducing and maintaining oral tolerance. There are several contact allergens, including fragrance, antioxidant, and preservative chemicals, to which subjects are exposed through both cutaneous and oral routes. We examine the possibility that oral tolerance to contact allergens may be more common than previously thought. Animal models of oral tolerance to contact allergens indicate that cutaneous exposure to small, subsensitizing doses of contact allergens might negate any subsequent attempts to induce tolerance by oral administration. Extrapolating these observations to common human practises raises the possibility that application of contact allergens (fragrances, preservatives and antioxidants) in consumer products used by children could prevent or inhibit the later acquisition of specific tolerance resulting from 'natural' dietary exposure after weaning. Existing data on formaldehyde may conflict with this theory, though this could be explained by allergen specificity. We propose that further work in this area is needed.