Breastfeeding and the prevalence of allergic diseases in schoolchildren: Does reverse causation matter?

Breastfeeding and risk of food allergy and allergic rhinitis in offspring: a systematic review and meta-analysis of cohort studies

The association between breastfeeding and the occurrence of allergic rhinitis (AR) and food allergy (FA) in offspring remains inconclusive. This review aims to comprehensively explore the potential relationships between various patterns and durations of breastfeeding and allergic diseases in offspring. We systematically searched PubMed, EMBASE, Cochrane, WOS databases, and Google Scholar for observational studies published up to March 30, 2023, that investigated the link between breastfeeding and allergies in offspring. The quality of the studies was assessed using the Newcastle-Ottawa Scale (NOS) and Joanna Briggs Institute (JBI). Pooled odds ratios (OR) and 95% confidence intervals (95% CI) were calculated employing an appropriate model based on the degree of heterogeneity. A total of 68 studies, encompassing 772,142 children, were ultimately included. The findings indicated that breastfeeding for more than 6 months was associated with a reduced risk of AR (OR = 0.88, 95% CI: 0.79 to 0.98) but posed a risk for FA (OR = 1.69, 95% CI: 1.27 to 2.25). Exclusive breastfeeding exhibited a protective effect against AR (OR = 0.94, 95% CI: 0.90 to 0.97), whereas non-breastfeeding was identified as a risk factor for AR (OR = 1.48; 95% CI: 1.03 to 2.12). No significant association was observed between breastfeeding patterns and FA.

CONCLUSION

Breastfeeding for more than 6 months proves to be an effective preventive measure against AR. However, large prospective high-quality studies are needed to investigate the potential risk of FA in children with prolonged breastfeeding.

WHAT IS KNOWN

• The impact of breastfeeding on allergic rhinitis and food allergy in offspring is controversial. • Previous meta-analyses fail to prove the effect of breastfeeding on food allergy in offspring of all ages.

WHAT IS NEW

• Breastfeeding for more than 6 months proves to be an effective preventive measure against AR. However, it potentially elevates the risk of FA in children. Non-breastfeeding is linked to an increased risk of AR in children, but there is no evidence of an association between breastfeeding patterns and FA in children. • The impact of breastfeeding on allergic rhinitis and food allergy in offspring may vary with the time and pattern of breastfeeding.

Analysis of Multimorbidity of Moderate to Severe Allergic Rhinitis in Children: A Real-World Study

INTRODUCTION

Allergic rhinitis (AR) in children is associated with various comorbidities, posing challenges for treatment and management. There have been few investigations of these multimorbidities in Chinese children with AR. Here, we investigated the prevalence of multimorbidities in children with moderate to severe AR and analyzed the influencing factors using real-world data.

METHODS

In total, 600 children who visited the outpatient clinic of our hospital and were diagnosed with moderate-severe AR were prospectively enrolled. All children underwent allergen detection and electronic nasopharyngoscopy. Parents or guardians completed a questionnaire that included age, sex, mode of delivery, feeding pattern, and familial history of allergy. The multimorbidities investigated included atopic dermatitis (AD), asthma, allergic conjunctivitis (AC), chronic rhinosinusitis (CRS), adenoid hypertrophy (AH), tonsil hypertrophy (TH), recurrent epistaxis, and recurrent respiratory tract infections (RRTIs).

RESULTS

The AR multimorbidities reported in children were as follows: recurrent epistaxis (46.5%), AC (46.3%), AD (40.7%), asthma (22.5%), RRIs (21.3%), CRS (20.5%), AH (19.7%), and TH (12.5%). In univariate logistic regression analysis, age (<6 years), birth mode, familial history of allergy, and single dust mite allergy were associated with AR multimorbidity (p < 0.05). Multivariate logistic regression revealed that a familial history of allergy was an independent risk factor for AC (odds ratio [OR] = 1.539, 95% confidence interval [CI]: 1.104-2.145) and AH (OR = 1.506, 95% CI: 1.000-2.267) (p < 0.05). Age (<6 years) was independently associated with the risk of AD (OR = 1.405, 95% CI: 1.003-1.969) and RRTIs (OR = 1.869, 95% CI: 1.250-2.793) (p < 0.05), cesarean section with AR and CRS risk (OR = 1.678, 95% CI: 1.100-2.561), and single dust mite allergy with asthma (OR = 1.590, 95% CI: 1.040-2.432) and CRS (OR = 1.600, 95% CI: 1.018-2.515) risk (p < 0.05). Further, non-dust mite allergy was independently associated with AR and CRS (OR = 2.056, 95% CI: 1.084-3.899).

CONCLUSION

AR was found to be accompanied by different comorbidities, including both allergic and non-allergic comorbidities, complicating disease treatment. These findings demonstrated that age (<6 years), familial history of allergy, types of allergens, and cesarean section were risk factors for different multimorbidities associated with AR.

The Role of Breastfeeding on Respiratory Outcomes Later in Childhood

BACKGROUND

Breastfeeding is associated with a lower risk of wheezing in early childhood, but its effect later in childhood remains unclear. We investigated the association of breastfeeding and respiratory outcomes in children aged 11 years.

MATERIALS AND METHODS

We performed an observational longitudinal study including 110 prepubertal children. Information about breastfeeding duration, wheezing and asthma was collected by questionnaires. At 11 years of age, we measured spirometry parameters, lung volumes, diffusing lung capacity, and fractional exhaled nitric oxide. We used logistic and linear regression models to examine the associations of breastfeeding duration with the odds of asthma and lung function measures. All multivariable analyses were adjusted for sex, smoking during pregnancy, gestational age at birth, twins, and mode of delivery (confounder model).

RESULTS

Breastfeeding duration was associated with FEV₁ z-score [β = 0.04, CI 95% (0.02-0.09)], FEF75 z-score [β = 0.06, CI 95% (0.03-0.09)] and FEV₁/FVC z-score [β = 0.03, CI 95% (0.00-0.07)], but not with diffusing lung capacity and fractional exhaled nitric oxide. No association of breastfeeding duration with preschool wheezing, ever asthma and current asthma was documented.

CONCLUSION

We showed that children breastfed for longer time presented higher FEV₁, FEV₁/FVC, and FEF75 z-score values at 11 years of age compared to children breastfed for shorter time, suggesting a protective effect of breastfeeding on airways, and not on lung parenchyma (lung volumes and alveolar capillary membrane) or allergic airway inflammation. The positive effect of breastfeeding duration on lung function lays the foundation to promote breastfeeding more and more as effective preventive measure.

Atopic Dermatitis: Conventional and Integrative Medicine

Although Western medicine and ideas about atopic dermatitis (AD) have become popular in many Asian countries, local beliefs about the disease and its treatment often prevail. The multi- racial background of these countries as well as the influence of the diverse religions (such as Taoism and Ramadan) in these regions often lead to diverse belief systems about the causes of AD (such as the Chi concept, also known as the balance of yin and yang) and the types of treatment (e.g. herbal remedies, topical versus concoctions, and decoctions). In addition, many of the cultural practices are preserved among the Southeast Asian minorities residing in the United Kingdom and North America. Eastern treatments typically take a holistic approach to AD and emphasize the psychosomatic component of the disorder. This overview provides a summary of the difference between conventional, complementary, alternative, and integrative medicine in terms of epidemiology, aetiology, therapy, and prognosis in children with AD. There are a number of similarities in genetic and environmental factors in epidemiology and aetiology; however, differences exist in terms of the concept of management. Complementary and alternative medicine, traditional Chinese medicine, and integrative medicine usage are not only prevalent among the Asian population but are also becoming more popular and accepted in Western societies.

Prolonged breastfeeding and protective effects against the development of allergic rhinitis: a systematic review and meta-analysis

BACKGROUND

There is insufficient evidence to confirm the protective effects of prolonged breastfeeding against the development of allergic rhinitis (AR).

METHODOLOGY

A systematic review and meta-analysis was performed to assess the associations between prolonged breastfeeding and AR symptoms later in life. Comparisons were conducted between breastfeeding durations less than 6 months and 6 months or more and between less than 12 months and 12 months or more. Exclusive breastfeeding and nonexclusive breastfeeding were analysed separately. Outcomes were risks of AR development later in life.

RESULTS

Twenty-three observational studies (161,611 children, age 2-18 years, 51.50% male) were included. Two studies (9%) were with high quality. Both exclusive and nonexclusive prolonged breastfeeding (6 months or more) decreased the risk of AR. The long-term (12 months or more) nonexclusive breastfeeding lowered the likelihood of AR compared to the 12 months or fewer. The long-term exclusive breastfeeding did not show the same protective effect; however, this result was restricted to only one study.

CONCLUSIONS

Exclusive breastfeeding and nonexclusive breastfeeding for 6 months or more may have protective effects against the development of AR up to 18 years of age. The findings should be interpreted with caution given the limitation of low-quality observational studies.

Possible Role of Environmental Factors in the Development of Food Allergies

The development of food allergies is thought to involve multiple factors, and it is unclear which conveys the most risk regarding this process. Since food allergy is a chronic disease without a cure at this time, understanding its development could provide an avenue for preventive practices and development of a curative treatment. Both historical and current data implicate maternal factors, genetics, and environmental exposures as major risk factors in the development of food allergy. An immature gut of the infant has been hypothesized as a possible route of sensitization. Breastfeeding until at least 6 months of age has been shown to have protective factors for the newborn and may possibly improve gut permeability. Newer studies such as the LEAP and EAT investigations also looked at early exposure and prevention of food allergies; their long-term results are critical in understanding early introduction and tolerance. Cutaneous exposure, oral exposure, and food protein exposure in house dust with their relation to the food allergy course are also a path of interest. Current research has shown sensitization can occur through impaired skin such as those with eczema and a filaggrin mutation. Tropomyosin and alpha-gal also are related to the complicated immunomodulatory factors involved in food allergy and allergic response. Cross-reactivity with plant allergens, sensitization to house dust mite and cockroach, and lone star tick bites can also induce food allergens in children and adults. Together, these factors provide a cohesive beginning to understanding how food allergies can occur and can influence further investigation into prevention, treatment, and eventual cure of food allergies.

Biases Inherent in Studies of Coffee Consumption in Early Pregnancy and the Risks of Subsequent Events

Consumption of coffee by women early in their pregnancy has been viewed as potentially increasing the risk of miscarriage, low birth weight, and childhood leukemias. Many of these reports of epidemiologic studies have not acknowledged the potential biases inherent in studying the relationship between early-pregnancy-coffee consumption and subsequent events. I discuss five of these biases, recall bias, misclassification, residual confounding, reverse causation, and publication bias. Each might account for claims that attribute adversities to early-pregnancy-coffee consumption. To what extent these biases can be avoided remains to be determined. As a minimum, these biases need to be acknowledged wherever they might account for what is reported.

Retrospective observational cohort study regarding the effect of breastfeeding on challenge-proven food allergy

BACKGROUND/OBJECTIVES

Human breast milk is generally regarded as the best nutrition for infants in their first months of life. Whether breastfeeding has a protective effect on food allergy is a point of debate and the subject of this study.

SUBJECTS/METHODS

This retrospective study was conducted in 649 children who underwent a double-blind placebo-controlled food challenge (DBPCFC) as part of routine care in a tertiary care clinic. Food allergy was defined as having at least one positive DBPCFC to any food. The association between both "any" breastfeeding (yes/no) and its duration in months with food allergy was studied by logistic regression analysis with correction for confounding variables.

RESULTS

The prevalence of food allergy was 58.9% (n = 382). Of all subjects, 75.8% (n = 492) was breastfed and 24.2% (n = 157) bottle-fed. There was no significant association between food allergy and breastfeeding versus bottle-feeding after correction for the confounding effect of increased breastfeeding by atopic parents and a history of asthma in the child (OR = 1.24, 95% CI = 0.85-1.79, p = 0.27). However, in breastfed children, every additional month of breastfeeding lowered the risk for food allergy by ~4% (OR = 0.96, 95% CI = 0.93-0.99, p = 0.02). No confounders were identified in this association.

CONCLUSION

These results show for the first time that in children investigated for possible food allergy, every additional month of breastfeeding is associated with a lower risk of developing clinical food allergy as diagnosed by DBPCFC. However, overall, there was no association between the prevalence of food allergy and breastfeeding versus bottle-feeding in this tertiary care population.

Systematic review: Early infant feeding practices and the risk of wheat allergy

AIM

Wheat is a common allergen. Early feeding practices (breastfeeding, potentially allergenic foods) might affect the risk of allergy. To systematically evaluate the association between early feeding practices and the risk of wheat allergy and sensitisation.

METHODS

Five databases were searched for studies of any design up to July 2015.

RESULTS

We included seven studies (five observational, low to moderate quality, two randomised controlled trials (RCTs), high quality). The results come from observational studies unless stated otherwise. Longer breastfeeding was associated with wheat allergy (two studies, n = 1847) and sensitisation (one study, n = 3781). Evidence for exclusive breastfeeding was contradictory; longer exclusive breastfeeding was associated with either lower (one study, n = 408) or higher (one study, n = 3781) risk of wheat sensitisation. Breastfeeding at gluten introduction did not affect the risk of wheat allergy (two studies, n = 2581). Introducing cereal ≥7 months of age increased the risk of wheat allergy (one study, n = 1612), but results from an RCT (n = 1303) showed no effect. Early introduction of gluten was associated with a reduced risk of wheat sensitisation up to 5 years in one observational study (n = 3781) but not in RCTs (n = 1303).

CONCLUSIONS

Based on limited evidence, the influence of breastfeeding and an early exposure to gluten on the risk of wheat allergy remain uncertain. There is no evidence supporting breastfeeding at gluten introduction as modifying the risk. Early introduction of gluten might reduce the risk of sensitisation, but currently, no evidence exists that it affects the risk of wheat allergy.

Breastfeeding and the risk of childhood asthma: A two-stage instrumental variable analysis to address endogeneity

BACKGROUND

Several explanations for the inconsistent results on the effects of breastfeeding on childhood asthma have been suggested. The purpose of this study was to investigate one unexplored explanation, which is the presence of a potential endogenous relationship between breastfeeding and childhood asthma. Endogeneity exists when an explanatory variable is correlated with the error term for reasons such as selection bias, reverse causality, and unmeasured confounders. Unadjusted endogeneity will bias the effect of breastfeeding on childhood asthma.

METHODS

To investigate potential endogeneity, a cross-sectional study of breastfeeding practices and incidence of childhood asthma in 87 pediatric patients in Georgia, the USA, was conducted using generalized linear modeling and a two-stage instrumental variable analysis. First, the relationship between breastfeeding and childhood asthma was analyzed without considering endogeneity. Second, tests for presence of endogeneity were performed and having detected endogeneity between breastfeeding and childhood asthma, a two-stage instrumental variable analysis was performed. The first stage of this analysis estimated the duration of breastfeeding and the second-stage estimated the risk of childhood asthma.

RESULTS

When endogeneity was not taken into account, duration of breastfeeding was found to significantly increase the risk of childhood asthma (relative risk ratio [RR]=2.020, 95% confidence interval [CI]: [1.143-3.570]). After adjusting for endogeneity, duration of breastfeeding significantly reduced the risk of childhood asthma (RR=0.003, 95% CI: [0.000-0.240]).

CONCLUSION

The findings suggest that researchers should consider evaluating how the presence of endogeneity could affect the relationship between duration of breastfeeding and the risk of childhood asthma.

Breastfeeding duration is inversely associated with asthma in Japanese children aged 3 years

OBJECTIVE

Recent meta-analyses found an inverse relationship between breastfeeding duration and asthma in children. The present cross-sectional study investigated the associations between breastfeeding duration and the prevalence of wheeze and asthma in Japanese children aged 3 years.

METHODS

Subjects were 6412 children who participated in the Kyushu Okinawa Child Health Study. Data were collected using a self-administered questionnaire. Wheeze was defined according to the criteria of the International Study of Asthma and Allergies in Childhood. Asthma was considered present if the child had been diagnosed by a physician as having asthma. Associations of breastfeeding duration with wheeze and asthma were estimated using multivariate generalized estimating equation methods adjusted for maternal, family, and health characteristics.

RESULTS

The prevalence values of wheeze and asthma were 19.5% and 7.0%, respectively. Compared with <4 months of exclusive breastfeeding, exclusive breastfeeding for ≥4 months was not significantly associated with wheeze or asthma. Compared with <10 months of breastfeeding duration regardless of exclusivity, 10 to <14 months, 14 to <19 months, and 19 months or more of breastfeeding duration regardless of exclusivity were independently inversely related to asthma: the adjusted odds ratios [ORs; 95% confidence intervals (CIs)] were 0.69 (0.52-0.91, p = 0.01), 0.73 (0.56-0.97, p = 0.03), and 0.67 (0.51-0.88, p = 0.004), respectively. No association was found between breastfeeding duration regardless of exclusivity and wheeze.

CONCLUSIONS

We confirmed an inverse association between breastfeeding duration regardless of exclusivity and asthma.

Breastfeeding patterns and its determinants among mothers living with Human Immuno-deficiency Virus -1 in four African countries participating in the ANRS 12174 trial

Background

HIV-1 transmission rates have been reduced over the last decade, an estimated 2 million new infections per year arise, including 220,000 paediatric cases. The main post-natal HIV exposure is through breastfeeding, where both its duration and modality (exclusive or not) are associated with postnatal transmission. The ANRS 12174 trial compared HIV-1 postnatal transmission of 2 prophylaxis drugs for infants during lactation (lamivudine and lopinavir-ritonavir). Our objective has been to examine the feeding practices and the determinants of exclusive/ predominant (EPBF) or any breastfeeding among the participants of this trial in Burkina Faso, South Africa, Uganda and Zambia.

Methods

Mothers infected with HIV-1 and their uninfected offspring were followed from day 7 after birth for 50 weeks, keeping monthly records of their feeding patterns. Feeding was classified into 3 categories: 1) exclusive breastfeeding during the first six months, only breast-milk being given to infant for 6 months, 2) predominant breastfeeding, breast-milk with liquid-based items being given, and 3) mixed feeding, other non-breast milk or solid food being given in addition to breast milk with or without liquid-based items. The categories were merged into 2 groups: EPBF applying to infants aged <6 months and mixed feeding applying to infants of any age. The feeding patterns have been given as Kaplan-Meier curves. A flexible parametric multiple regression model was used to identify the determinants of the mothers’ feeding behaviour.

Results

A total of 1,225 mother-infant pairs provided feeding data from Burkina Faso (N = 204), South Africa (N = 213), Uganda (N = 274) and Zambia (N = 534) between November 2009 and March 2013. The mean maternal age was 27.4 years and the mean BMI was 24.5. 57.7 and 93.9% of mothers initiated breastfeeding within the first hour and first day, respectively. Overall, the median durations of any form of breastfeeding and EPBF were 40.6, and 20.9 weeks, respectively. Babies randomized to the lopinavir/ritonavir group in South Africa tended to do less EPBF than those in the lamivudine group.

Overall the group of mothers aged between 25 and 30 years, those married, employed or multiparous tended to stop early EPBF. Mothers living in Uganda or Zambia, those aged between 25 -30 years, better educated (at least secondary school level), employed or having undergone C-section stopped any breastfeeding early.

Conclusions

There is a need to improve breastfeeding and complementary feeding practices of children, particularly those exposed to HIV and anti-retrovirals, taking into account context and socio-demographic factors.

Trial registration

Clinical trial registration: NCT00640263.

Electronic supplementary material

The online version of this article (doi:10.1186/s13006-017-0112-2) contains supplementary material, which is available to authorized users.

Food-Related Symptoms and Food Allergy in Swedish Children from Early Life to Adolescence

Background

Risk factors for persistence of food-related symptoms (FRS) and food allergy (FA) from early life to adolescence are incompletely understood. The aim of this study was to identify risk factors for FRS and FA in adolescence amongst children with FRS or FA in the first four years of life (early life).

Methods

In children enrolled in a Swedish birth cohort and followed to 16 years (n = 2572), we defined children with early life FRS in the absence of FA, and FA. Corresponding phenotypes were defined at 16 years. Associations between potential risk factors at 4 years and FRS and FA at 16 years were investigated using logistic regression.

Results

Early life FRS and FA prevalences were 12.2% and 6.8%, respectively. Amongst children with early life FRS, 35.7% had FRS or FA at 16 years, whereas 74.3% of the children with early life FA had FA at 16 years. For each of the early life phenotypes, parental allergy, early life allergic multimorbidity, early life reactions to peanuts/tree nuts and IgE reactivity at 4 years were statistically significantly associated with FRS or FA at 16 years. In contrast, male sex was associated with an increased risk of FA at 16 years among children with early life FA only.

Conclusions

In early life, food-related symptoms are twice as common as food allergy. Unlike food allergy, food-related symptoms often remit by adolescence. Yet, these phenotypes have many common risk factors for persistence to adolescence.

Breastfeeding and timing of first dietary introduction in relation to childhood asthma, allergies, and airway diseases: A cross-sectional study

OBJECTIVES

We investigated associations of breastfeeding (BF) durations and patterns and of timing of other dietary introductions with prevalence of asthma, wheeze, hay fever, rhinitis, pneumonia, and eczema among preschool children.

METHODS

During April 2011-April 2012, we conducted a cross-sectional study in 72 kindergartens from five districts of Shanghai, China and obtained 13,335 questionnaires of children 4-6-years-old. We used multiple logistic regression models to evaluate the target associations.

RESULTS

Compared to children who were never BF, children who were exclusively breastfed 3-6 months had the lowest risk of asthma (adjusted odds ratio and 95% confidence interval: 0.81, 0.72-0.91) and wheeze (0.93, 0.87-0.99); and exclusive BF >6 months was significantly associated with a reduced risk of hay fever (0.93, 0.89-0.97), rhinitis (0.97, 0.94-0.99), pneumonia (0.97, 0.94-0.99), and eczema (0.96, 0.93-0.99). No significant associations were found between time when fruits or vegetables were introduced and the studied diseases. Associations were independent of the child's sex and parent's ownership of the current residence. Longer duration BF was only significantly protective when there was no family history of atopy.

CONCLUSIONS

This study suggests that heredity, but not sex and socioeconomic status, may negatively impact the effect of BF on childhood airway and allergic diseases. Our findings support China's national recommendation that mothers provide exclusive BF for the first four months, and continue partial BF for more than 6 months.

Early weaning is beneficial to prevent atopic dermatitis occurrence in young children

BACKGROUND

Epidemiological data on infant feeding practices and allergic diseases are controversial. The purpose of this study was to explore the association of early weaning with the occurrence of atopic dermatitis (AD).

METHODS

We conducted a matched case-control study on incident physician-diagnosed AD in early childhood including 451 cases and 451 controls. Data on several factors, including feeding practices, were collected through an interviewer-administered questionnaire. Odds ratios (OR) and the corresponding 95% confidence intervals (CIs) were estimated through logistic regression models, conditioned on study center, age, sex, and period of interview, and adjusted for potential confounders.

RESULTS

Early weaning, defined as the introduction of solid foods at 4 or 5 months of age, was inversely related to the risk of AD, with children weaned at 4 months having lower AD risk (OR = 0.41, 95% CI, 0.20-0.87) compared to those exclusively breastfed. Similar results were observed for weaning started at 5 months of age (OR = 0.39, 95% CI, 0.18-0.83). This association persisted when children with and without family history of allergy were considered separately. Prolonged partial breastfeeding (breastmilk plus milk formulas) was not associated with AD. Consistently, the introduction of a high number of different solid foods reduced the risk of AD (P trend = 0.02 at 4 months of age and P trend = 0.04 at 5 months).

CONCLUSION

Our data provide evidence against the preventing role of prolonged exclusive (but not partial) breastfeeding in AD occurrence and confirm recent results indicating a beneficial role of early weaning in AD.

Breastfeeding and asthma and allergies: a systematic review and meta-analysis

AIM

To systematically review the association between breastfeeding and childhood allergic disease.

METHODS

Predetermined inclusion/exclusion criteria identified 89 articles from PubMed, CINAHL and EMBASE databases. Meta-analyses performed for categories of breastfeeding and allergic outcomes. Meta-regression explored heterogeneity.

RESULTS

More vs. less breastfeeding (duration) was associated with reduced risk of asthma for children (5-18 years), particularly in medium-/low-income countries and with reduced risk of allergic rhinitis ≤5 years, but this estimate had high heterogeneity and low quality. Exclusive breastfeeding for 3-4 months was associated with reduced risk of eczema ≤2 years (estimate principally from cross-sectional studies of low methodological quality). No association found between breastfeeding and food allergy (estimate had high heterogeneity and low quality). Meta-regression found differences between study outcomes may be attributable to length of breastfeeding recall, study design, country income and date of study inception. Some of the protective effect of breastfeeding for asthma may be related to recall bias in studies of lesser methodological quality.

CONCLUSION

There is some evidence that breastfeeding is protective for asthma (5-18 years). There is weaker evidence for a protective effect for eczema ≤2 years and allergic rhinitis ≤5 years of age, with greater protection for asthma and eczema in low-income countries.

The relationship between the season of birth and early-onset food allergies in children

BACKGROUND

This study examined the relationship between the season of birth (SoB) and other factors with the development of FA.

METHODS

A multicenter, cross-sectional pilot study recruited 1197 patients with FA. The main study recruited 440 incident cases (FA group) definitively diagnosed as FA at 0-1 year of age. In both studies, the frequency of autumn-winter births (AWBs) in FA patients was compared to the regional control population. In the main study, we analyzed the differences in the SoB and other factors between patients in the FA group and those in the non-FA group (n = 332) in allergy clinics.

RESULTS

The pilot study showed that the frequency of AWB (57.6%) in the FA patients was significantly higher than that of the regional control population (50.4%, OR, 1.34; p < 0.001). The main study also showed the dominance of AWB (62.7%) in the FA group in comparison with that in the regional control population (50.2%, OR, 1.70; p < 0.001). Preterm birth (OR, 0.43; p = 0.027) and the presence of two or more elder siblings (OR, 0.27; p = 0.012) were significantly associated with a lower frequency of FA than those of non-FA. AWB (RR, 1.21; p = 0.020) and preterm birth (RR, 0.55; p = 0.017) were significantly associated with a number of trigger foods. The SoB effect was observed in FA patients irrespective of the presence of infantile eczema.

CONCLUSIONS

AWB was predominant in the patients with newly diagnosed food allergies.

Sun exposure inversely related to food sensitization during infancy

BACKGROUND

Autumn and winter birth (AWB) has been reported to be a risk factor for the development of food allergies. However, the association between seasonal factors and allergic sensitization during early infancy remains unclear.

METHODS

We collected data from 732 patients regarding the total and specific immunoglobulin E (tIgE, sIgE) levels in infants younger than 6 months old from November 2001 to October 2012 from the institutional clinical database system. We then analyzed the relationship between the birth month and the value of each parameter. Furthermore, we identified any correlations between the number of sensitized patients and the monthly climatological parameters.

RESULTS

The number of tIgE samples obtained from AWB patients (n = 482) was 2.1 times higher than that from patients born in the spring and summer (SSB, n = 225). The number of sIgE samples to egg white, cow's milk, and wheat, the sensitized ratio and the median sIgE titer were also all higher in AWB. The number of sensitized AWB patients to these allergens was 2.75, 3.05, and 3.97 times higher, respectively. A periodic change in the number of sensitized patients was observed annually (highest in October-November and lowest in May). Among the climatological parameters examined, the average solar radiation during the 3-month period after birth showed the strongest negative correlation with the number of sensitized patients (egg white: r = -0.976, cow's milk: r = -0.969, wheat: r = -0.975).

CONCLUSIONS

The amount of solar radiation immediately after birth had a strong negative correlation with allergen sensitization before 6 months of age.

Breastfeeding Initiation and Continuation by Employment Status among Korean Women

PURPOSE

The objective of this study was to examine the factors associated with initiation and continuation of breastfeeding among Korean women in relation to their employment status.

METHODS

Data were collected using a web-based self-administered questionnaire from 1,031 Korean mothers living in Seoul with babies younger than 24 months. Demographic characteristics, education on breastfeeding, rooming in, breastfeeding during hospital stay, and breastfeeding knowledge were examined. Multivariate logistic regression analyses were performed to identify factors associated with initiation and continuation at 1, 6 and 12 months according to mothers' employment status.

RESULTS

Breastfeeding initiation rates were similar regardless of mothers' employment status. Continuation rates decreased for both groups of mothers, but were significantly lower among employed mothers at all duration points. Unemployed mothers who were able to keep their babies in the same room during the hospital stay were more likely to initiate breastfeeding. The factor that was consistently associated with breastfeeding continuation for all duration points among unemployed mothers was whether the mother breastfed during the hospital stay. Higher knowledge scores and having an infant with atopic dermatitis were also associated with breastfeeding continuation at 6 months and 12 months, respectively for unemployed mothers, and receiving education on breastfeeding was associated with 12-month continuation for employed mothers.

CONCLUSION

These results emphasize the significant roles of hospitals for breastfeeding initiation and continuation, with rooming-in, initial breastfeeding practice and education during hospital stay as important practices. In addition, for working mothers to continue their breastfeeding, significant support from the workplace is crucial.

Breast-feeding and health consequences in early childhood: is there an impact of time-dependent confounding?

BACKGROUND

Estimated effects of breast-feeding on childhood health vary between studies, possibly due to confounding by baseline maternal and child characteristics. Possible time-dependent confounding has received little consideration. Our aim was to evaluate the impact of such confounding.

METHODS

We estimated the relationship between cumulative exclusive breast-feeding up to 6 months and wheezing, rash and body mass index (BMI) at 12 months [in the Whistler cohort (n = 494) and PROBIT (n = 11,463)], and wheezing, rash, asthma, hay fever, eczema, allergy and BMI at age 6.5 years (PROBIT). We adjusted for time-dependent confounding by weight, length, rash, respiratory illness and day care attendance using marginal structural models (MSMs).

RESULTS

Weight and day care attendance appeared potential time-dependent confounders, since these predicted breast-feeding status and were influenced by previous breast-feeding. However, adjustment for time-dependent confounders did not markedly change the estimated associations. For example, in PROBIT the adjusted increase in BMI at 12 months per 1-month increase in exclusive breast-feeding was 0.04 (95% CI -0.09 to 0.01) using logistic regression and -0.06 (95% CI -0.11 to -0.01) using MSM. In Whistler, these estimates were each -0.05 (95% CI -0.10 to 0.00).

CONCLUSIONS

In two cohort studies, there was little evidence of time-dependent confounding by weight, length, rash, respiratory illness or day care attendance of the effects of breast-feeding on early childhood health.

Breastfeeding and risk of atopic dermatitis up to the age 42 months: a birth cohort study in Japan

PURPOSE

The purpose of this study was to investigate the association between breastfeeding and atopic dermatitis (AD) up to the age 42 months.

METHODS

Data from a nationally representative population-based birth cohort study in Japan were used (N = 38,757). Feeding pattern and breastfeeding duration were investigated via questionnaires when infants were aged 6 months. Physician-diagnosed AD during the previous 1 year was ascertained via questionnaires when the children were aged 18, 30, and 42 months. The associations between feeding patterns or breastfeeding duration and physician-diagnosed AD from the age 6 to 42 months, categorized by AD status (no history of AD, episodic AD, and persistent AD), were analyzed using ordered logistic regression adjusted for covariates.

RESULTS

Breastfeeding was positively associated with AD, with dose-response association (P for trend < .001). Exclusively breastfed infants were 1.26 times more likely to have AD (95% confidence interval, 1.12-1.41) than infants fed formula alone. Furthermore, children with a longer breastfeeding duration were also significantly more likely to have AD (P for trend < .001).

CONCLUSIONS

Breastfeeding is associated with an increased risk of AD up to the age 42 months. Further study is needed to elucidate the mechanism underlying the association between breastfeeding and AD.

Food allergy: temporal trends and determinants

This review summarizes studies discussing temporal trends in the prevalence of food allergy as well as potential factors associated with the development of food allergy. In addition, we will address the potential hypotheses accounting for the apparent increase in food allergy prevalence. Studies suggest increased prevalence of food allergy. However, relatively little is known about its pathogenesis. This review aims to assess temporal trends in the prevalence of food allergy and discuss potential genetic, environmental, and demographic determinants. The search strategy examined the medical literature database MEDLINE (using PubMed) for the time period of January 1, 2002 to January 31, 2012. In recent decades, the prevalence of food allergy in general has increased by 0.60 % [95 % confidence interval (CI), 0.59 %-0.61 %] and the prevalence of peanut allergy by 0.027 % (95 % CI, 0.026 %-0.028 %), but it has now likely stabilized in developed countries. Genes, the environment, and demographic characteristics play a role in the pathogenesis of food allergy. Numerous environmental and demographic factors as well as gene-environment interactions may account for this increase in prevalence, but further studies are required to tease out their relative contribution.

Food allergy and anaphylaxis in pediatrics: update 2010-2012

This review highlights the progress made in food allergy (FA) and anaphylaxis research in pediatrics published in the journal Pediatric Allergy and Immunology since 2010. Putative risk factors for FA are as follows: a family history of allergic disease, particularly in the mother, low birth order, season of birth, and severe atopic eczema. Obstetric practices, antibiotic use, and home environment are factors deserving further research. Diagnostic decision levels and component-specific IgE are useful in the diagnosis of FA; however, oral food challenges remain the gold standard and may also be a means to reduce parental anxiety and to improve education. Oral immunotherapy studies show promise in increasing the threshold of reactivity of allergic patients and therefore improving their quality of life. In single-nut-allergic patients, introduction of other nuts allows broadening the diet and thus reducing the psychological impact of allergen avoidance. Nutritional deficiencies are not uncommon in food-allergic children and should be specifically assessed. The prescription of injectable adrenaline is still insufficient and not consistent among practitioners, requiring improved training and implementation of guidelines. Current research into the epidemiology and immunological mechanisms of FA and tolerance will enable us to devise strategies to both prevent and treat food allergies.

A retrospective chart review to identify perinatal factors associated with food allergies

Background

Gut flora are important immunomodulators that may be disrupted in individuals with atopic conditions. Probiotic bacteria have been suggested as therapeutic modalities to mitigate or prevent food allergic manifestations. We wished to investigate whether perinatal factors known to disrupt gut flora increase the risk of IgE-mediated food allergies.

Methods

Birth records obtained from 192 healthy children and 99 children diagnosed with food allergies were reviewed retrospectively. Data pertaining to delivery method, perinatal antibiotic exposure, neonatal nursery environment, and maternal variables were recorded. Logistic regression analysis was used to assess the association between variables of interest and subsequent food allergy diagnosis.

Results

Retrospective investigation did not find perinatal antibiotics, NICU admission, or cesarean section to be associated with increased risk of food allergy diagnosis. However, associations between food allergy diagnosis and male gender (66 vs. 33; p=0.02) were apparent in this cohort. Additionally, increasing maternal age at delivery was significantly associated with food allergy diagnosis during childhood (OR, 1.05; 95% CI, 1.017 to 1.105; p=0.005).

Conclusions

Gut flora are potent immunomodulators, but their overall contribution to immune maturation remains to be elucidated. Additional understanding of the interplay between immunologic, genetic, and environmental factors underlying food allergy development need to be clarified before probiotic therapeutic interventions can routinely be recommended for prevention or mitigation of food allergies. Such interventions may be well-suited in male infants and in infants born to older mothers.

Birth order effect on childhood food allergy

Higher birth order is associated with a smaller risk of allergy (birth order effect). The purpose of this study was to compare the significance of the birth order effect on the prevalence of specific allergic diseases [bronchial asthma (BA), atopic dermatitis (AD), allergic rhinitis (AR), allergic conjunctivitis (AC), and food allergy (FA)] among schoolchildren. A questionnaire survey dealing with the prevalence of allergic diseases was administered to the parents of 14,669 schoolchildren aged 7-15 yr. Based on the data, the prevalence of each allergic disease was compared according to birth order (1st, 2nd, and 3rd or later). Multiple regression analysis was performed to test the significance of the differences. There was no significant difference in the prevalence of BA or AD according to birth order. The prevalence of AR, AC, and FA decreased significantly as birth order increased. The prevalence of FA among those with 1st, 2nd, and 3rd or later birth order was 4.0%, 3.4%, and 2.6%, respectively (p = 0.01). With respect to symptoms in infancy, the prevalence of wheeze increased significantly and that of FA and eczema in infancy decreased significantly as birth order increased. The present data show a significant birth order effect on FA. The effect was also observed for the prevalence of FA and eczema in infancy. These data support the concept of early, non-allergen-specific programming of IgE-mediated immunity.

Breastfeeding and lung function at school age: does maternal asthma modify the effect?

RATIONALE

The evidence for an effect of breastfeeding on lung function is conflicting, in particular whether the effect is modified by maternal asthma.

OBJECTIVES

To explore the association between breastfeeding and school-age lung function.

METHODS

In the Leicestershire Cohort Studies we assessed duration of breastfeeding (not breastfed, ≤3 months, 4-6 months, and >6 months), other exposures, and respiratory symptoms by repeated questionnaires. Post-bronchodilator FVC, FEV(1), peak expiratory flow (PEF), forced midexpiratory flow (FEF(50)), and skin prick tests were measured at age 12 years. We performed multivariable linear regression and tested potential causal pathways (N = 1,458).

MEASUREMENTS AND MAIN RESULTS

In the entire sample, FEF(50) was higher by 130 and 164 ml in children breastfed for 4 to 6 months and longer than 6 months, respectively, compared with those not breastfed (P = 0.048 and 0.041), with larger effects if the mother had asthma. FVC and FEV(1) were associated with breastfeeding only in children of mothers with asthma (P for interaction, 0.018 and 0.008): FVC was increased by 123 and 164 ml for those breastfed 4 to 6 months or longer than 6 months, respectively (P = 0.177 and 0.040) and FEV(1) was increased by 148 and 167 ml, respectively (P = 0.050 and 0.016). Results were unchanged after adjustment for respiratory infections in infancy and asthma and atopy in the child.

CONCLUSIONS

In this cohort, breastfeeding for more than 4 months was associated with increased FEF(50) and, in children of mothers with asthma, with increased FEV(1) and FVC. It seems that the effect is not mediated via avoidance of early infections or atopy but rather through a direct effect on lung growth.

Breastfeeding, asthma, and allergy: a tale of two cities

BACKGROUND

The effect of breastfeeding duration on subsequent asthma and allergy remains the subject of much controversy.

OBJECTIVE

To investigate whether differences in study design or disease-related exposure modification were the cause of the differences in study findings.

METHOD

The data from two cohorts, the Childhood Asthma Prevention Study (CAPS) from Australia and the Barn Allergi Miljo Stockholm cohort from Sweden, which had reported different findings on the association between breastfeeding and asthma, were combined. For this analysis, the definitions for breastfeeding, asthma, and allergy were harmonized. Subjects were included if they had at least one parent with wheeze or asthma and had a gestational age of more than 36 wks (combined n = 882). The risk of disease-related exposure modification was assessed using survival analysis.

RESULTS

Breastfeeding reduced the risk of asthma at 4/5 and 8 yrs of age in children with a family history of asthma. The effect was stronger in the Swedish cohort. Breastfeeding had no effect on the prevalence of sensitization to inhaled allergens in this cohort with a family history of asthma but was a risk factor for sensitization to cow's milk, peanuts, and eggs in the CAPS cohort at 4/5 yrs and in the combined cohort at 8 yrs. There was no evidence to support the existence of disease-related exposure modification in either cohort.

CONCLUSION

These findings point to the importance of harmonization of features of study design, including subject selection criteria and variable definitions, in resolving epidemiological controversies such as those surrounding the impact of breastfeeding on asthma and allergic sensitization.

Perinatal programming of asthma: the role of gut microbiota

Perinatal programming, a dominant theory for the origins of cardiovascular disease, proposes that environmental stimuli influence developmental pathways during critical periods of prenatal and postnatal development, inducing permanent changes in metabolism. In this paper, we present evidence for the perinatal programming of asthma via the intestinal microbiome. While epigenetic mechanisms continue to provide new explanations for the programming hypothesis of asthma development, it is increasingly apparent that the intestinal microbiota plays an independent and potentially interactive role. Commensal gut bacteria are essential to immune system development, and exposures disrupting the infant gut microbiota have been linked to asthma. This paper summarizes the recent findings that implicate caesarean delivery, breastfeeding, perinatal stress, probiotics, and antibiotics as modifiers of infant gut microbiota in the development of asthma.

Food allergy and atopic dermatitis: how are they connected?

Food allergy predominantly affects children rather than adults with atopic dermatitis (AD). Early food sensitization has been found to be significantly associated with AD. Three different patterns of clinical reactions to food allergens in AD patients have been identified: 1) immediate-type symptoms, 2) isolated eczematous late-type reactions, and 3) combined reactions. Whereas in children, allergens from cow's milk, hen's egg, soy, wheat, fish, peanut, or tree nuts are primarily responsible for allergic reactions, birch pollen-related food allergens seem to play a major role in adolescent and adults with AD in Central and Northern Europe. Defects in the epidermal barrier function seem to facilitate the development of sensitization to allergens following epicutaneous exposure. The relevance of defects in the gut barrier as well as genetic characteristics associated with an increased risk of food allergy remain to be further investigated. Many studies focus on sufficient strategies of prevention, which actually include breastfeeding or feeding with hydrolyzed formula during the first 4 months of life.

Gene polymorphisms, breast-feeding, and development of food sensitization in early childhood

BACKGROUND

The effect of breast-feeding on the development of allergic disease is uncertain. There are no data that show whether this relationship varies by individual genotypes.

OBJECTIVE

We sought to evaluate the effect of breast-feeding and gene-breast-feeding interactions on food sensitization (FS) in a prospective US birth cohort.

METHODS

This study included 970 children who were prospectively followed since birth. Breast-feeding history was obtained from a standardized questionnaire interview. FS was defined as a specific IgE level of 0.35 kU(A)/L or greater to any of 8 common food allergens. Eighty-eight potentially functional single nucleotide polymorphisms (SNPs) were genotyped from 18 genes involved in innate immunity or T(H)1/T(H)2 balance. Logistic regression models were used to test the effects of breast-feeding and gene-breast-feeding interactions on FS, with adjustment for pertinent covariates.

RESULTS

Children who were ever breast-fed (n = 739), including exclusively breast-fed children, were at a 1.5 (95% CI, 1.1-2.1; P = .019) times higher risk of FS than never breast-fed children (n = 231). This association was significantly modified by rs425648 in the IL-12 receptor β1 gene (IL12RB1; P for interaction = .0007): breast-feeding increased the risk of FS (odds ratio, 2.0; 95% CI, 1.4-3.1; P = .0005) in children carrying the GG genotype but decreased the risk (odds ratio, 0.6; 95% CI, 0.3-1.4; P = .252) in children carrying the GT/TT genotype. Similar interactions were observed for SNPs in the Toll-like receptor 9 (TLR9; rs352140) and thymic stromal lymphopoietin (TSLP; rs3806933) genes. The interaction between the combined genotypes of the 3 SNPs and breast-feeding on FS was even stronger (P for interaction < 10⁻⁵).

CONCLUSION

Our data suggest that the effect of breast-feeding on FS was modified by SNPs in the IL12RB1, TLR9, and TSLP genes both individually and jointly. Our findings underscore the importance of considering individual genetic variations in assessing this relationship.

Infant nutrition and allergy

Over the past several decades, the incidence of atopic diseases such as asthma, atopic dermatitis and food allergies has increased dramatically. Although atopic diseases have a clear genetic basis, environmental factors, including early infant nutrition, may have an important influence on their development. Therefore, attempts have been made to reduce the risk of the development of allergy using dietary modifications, mainly focused on longer breast-feeding and delayed introduction or elimination of foods identified as potentially most allergenic. Recently, there is also an increasing interest in the active prevention of atopy using specific dietary components. Many studies have shown that breast-feeding may have the protective effect against future atopic dermatitis and early childhood wheezing. Concerning complementary feeding, there is evidence that the introduction of complementary foods before 4 months of age may increase the risk for atopic dermatitis. However, there is no current convincing evidence that delaying introduction of solids after 6 months of age has a significant protective effect on the development of atopic disease regardless of whether infants are fed cow's milk protein formula or human subject's milk, and this includes delaying the introduction of foods that are considered to be highly allergic, such as fish, eggs and foods containing peanut protein. In conclusion, as early nutrition may have profound implications for long-term health and atopy later in life, it presents an opportunity to prevent or delay the onset of atopic diseases.