The relationship of breast-feeding, overweight, and asthma in preadolescents

Breast feeding, obesity, and asthma association: clinical and molecular views

Asthma is a chronic condition that affects children worldwide. Accumulating number of studies reported that the prevalence of pediatric obesity and asthma might be altered through breastfeeding. It has been proposed that Leptin, which exists in human milk, is oppositely associated with weight increase in newborns. It may also influence peripheral immune system by promoting TH1 responses and suppressing TH2 cytokines. Leptin influences body weight and immune responses through complex signaling pathways at molecular level. Although previous studies provide explanations for the protective role of breastfeeding against both obesity and asthma, other factors such as duration of breastfeeding, parental, and prenatal factors may confound this relationship which requires further research.

From Beneath the Skin to the Airway Wall: Understanding the Pathological Role of Adipose Tissue in Comorbid Asthma-Obesity

This article provides a contemporary report on the role of adipose tissue in respiratory dysfunction. Adipose tissue is distributed throughout the body, accumulating beneath the skin (subcutaneous), around organs (visceral), and importantly in the context of respiratory disease, has recently been shown to accumulate within the airway wall: "airway-associated adipose tissue." Excessive adipose tissue deposition compromises respiratory function and increases the severity of diseases such as asthma. The mechanisms of respiratory impairment are inflammatory, structural, and mechanical in nature, vary depending on the anatomical site of deposition and adipose tissue subtype, and likely contribute to different phenotypes of comorbid asthma-obesity. An understanding of adipose tissue-driven pathophysiology provides an opportunity for diagnostic advancement and patient-specific treatment. As an exemplar, the potential impact of airway-associated adipose tissue is highlighted, and how this may change the management of a patient with asthma who is also obese. © 2023 American Physiological Society. Compr Physiol 13:4321-4353, 2023.

Effect of childhood BMI on asthma: a systematic review and meta-analysis of case-control studies

Background

Asthma is a multifactorial syndrome that threatens the health of children. Body mass index (BMI) might be one of the potential factors but the evidence is controversial. The aim of this study is to perform a comprehensive meta-analysis to investigate the association between asthma and BMI.

Methods

Electronic databases including, Web of Science, Pubmed, Scopus, Science Direct, ProQuest, up to April 2017, were searched by two researchers independently. The keywords “asthma, body mass index, obesity, overweight, childhood and adolescence” were used. Random and fixed effects models were applied to obtain the overall odds ratios (ORs) and standardized mean difference (SMD). Heterogeneity between the studies was examined using I² and Cochrane Q statistics.

Results

After reviewing 2511 articles, 16 studies were eligible for meta-analysis according to inclusion/exclusion criteria. A meta-analysis from 11 case-control studies revealed OR of asthma and overweight as OR = 1.64; (95% Confidence Interval (CI): 1.13–2.38) and from 14 case-control studies, OR for asthma and obesity was OR = 1.92 (95% CI: 1.39–2.65), which indicated that risk of asthma in overweight and obese children and adolescence was significantly higher (1.64 and 1.92 times) than that of individuals with (p-value < 0.01 for underweight/normal weight in both cases). Furthermore, there was a significant relationship between asthma and BMI > 85 percentile according to SMD SMD = 0.21; (95%CI: 0.03–0.38; p-value = 0.021).

Conclusions

The results showed a significant relationship between BMI (obesity/overweight) and asthma among children and adolescents. It is important to study the confounding factors that affect the relationship between asthma and BMI in future epidemiological researches.

Electronic supplementary material

The online version of this article (10.1186/s12887-018-1093-z) contains supplementary material, which is available to authorized users.

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.

Babies Galore; or recent findings and future perspectives of pregnancy cohorts with a focus on immunity

Population-based pregnancy cohorts recruiting women before or at the moment of childbirth allow a longitudinal follow-up on children's health later in life. Important findings arising from pregnancy cohorts are discussed in the present review. These insights have led to revised guidelines on how to minimize disease risks in children, e.g., in the context of chronic immune diseases including allergies and asthma. Moreover, insights from pregnancy cohorts also unveiled a collateral effect of pregnancy on maternal immunity, mirrored by an ameliorated course of certain autoimmune diseases, but also an increased risk of infection with influenza A virus. Future pregnancy cohort studies are still required to close gaps in knowledge on how parameters involved in the developmental origin of health or poor immunity observed in children later in life are operational. We discuss here features that should be covered by future pregnancy cohort studies. Expected insights from such studies will then lay the foundation for biomarker discovery and offer opportunities for interventions to ameliorate adverse immune responses in humans.

Prevention of asthma: where are we in the 21st century?

Asthma is the most common chronic disease of childhood and, in the latter part of the 20th century, reached epidemic proportions. Asthma is generally believed to result from gene-environment interactions. There is consensus that a 'window of opportunity' exists during pregnancy and early in life when environmental factors may influence its development. We review multiple environmental, biologic and sociologic factors that may be important in the development of asthma. Meta-analyses of studies have demonstrated that multifaceted interventions are required in order to develop asthma prevention. Multifaceted allergen reduction studies have shown clinical benefits. Asthma represents a dysfunctional interaction with our genes and the environment to which they are exposed, especially in fetal and early infant life. The increasing prevalence of asthma also may be an indication of increased population risk for the development of other chronic non-communicable autoimmune diseases. This review will focus on the factors which may be important in the primary prevention of asthma. Better understanding of the complex gene-environment interactions involved in the development of asthma will provide insight into personalized interventions for asthma prevention.

Breastfeeding and childhood asthma: systematic review and meta-analysis

Asthma and wheezing disorders are common chronic health problems in childhood. Breastfeeding provides health benefits, but it is not known whether or how breastfeeding decreases the risk of developing asthma. We performed a systematic review and meta-analysis of studies published between 1983 and 2012 on breastfeeding and asthma in children from the general population. We searched the PubMed and Embase databases for cohort, cross-sectional, and case-control studies. We grouped the outcomes into asthma ever, recent asthma, or recent wheezing illness (recent asthma or recent wheeze). Using random-effects meta-analyses, we estimated pooled odds ratios of the association of breastfeeding with the risk for each of these outcomes. We performed meta-regression and stratified meta-analyses. We included 117 of 1,464 titles identified by our search. The pooled odds ratios were 0.78 (95% confidence interval: 0.74, 0.84) for 75 studies analyzing "asthma ever," 0.76 (95% confidence interval: 0.67, 0.86) for 46 studies analyzing "recent asthma," and 0.81 (95% confidence interval: 0.76, 0.87) for 94 studies analyzing recent wheezing illness. After stratification by age, the strong protective association found at ages 0-2 years diminished over time. We found no evidence for differences by study design or study quality or between studies in Western and non-Western countries. A positive association of breastfeeding with reduced asthma/wheezing is supported by the combined evidence of existing studies.

Early childhood nutritional status in CARICOM countries: an overview with respect to five nutrition related millennium development goals

Previous reviews of nutritional status in children under 5 years describe the Caribbean grouped with Latin America. This paper focuses specifically on the Caribbean and the goals and targets of the Millennium Declaration that have bearing on childhood development. The results indicate that CARICOM countries have made progress in terms of child health as assessed by gross health indicators. Yet, the millennium generation experiences coexistence of undernutrition and overweight in early childhood. The associations of GNI with markers such as poverty indices are somewhat inconsistent with traditional findings and highlight a need to reassess the causes of infant mortality and low birth weight. However, a lack of systematic local data has hampered progress on an individual country basis. Interventions that deal more pointedly with country specific needs are required including those targeting obesity if the MDGs are to be attained by all member states.

Is there a role for probiotics in the prevention or treatment of food allergy?

A balanced gut microbiota is crucial for the development of healthy immunoregulation and gut barrier function to allow brisk immune responses to pathogens and systemic hyporesponsiveness to harmless antigens such as food. Although the first allergic disease to manifest itself, atopic eczema, is not equivalent to food allergy, pre- and postnatal administration of specific probiotic strains has emerged as a promising tool for the prevention of this condition, with potential implications for food allergy development. For food allergy proper, however, we lack markers and risk factors and mechanisms, i.e., targets for preventive measures. The focus here is therefore on the treatment. Indeed, the potential of specific probiotic strains to alleviate food allergy resides in their ability to modify antigens, repair gut barrier functions, balance altered microbiota, and restore local and systemic immune regulation. In patients with multiple food allergies, induction of oral tolerance by specific probiotics continues to attract research interest.

A systematic review of the association between obesity and asthma in children

AIM

To provide a comprehensive integration of contemporary studies focusing on the relationship between obesity and asthma in paediatric populations.

BACKGROUND

The simultaneous increase in asthma and obesity prevalence has been widely discussed over the past 20 years. Although studies have discovered a positive correlation between the two, evidence-based findings are needed to develop nursing interventions.

DESIGN

A quantitative systematic review on the literature was conducted from June-December 2011.

DATA SOURCES

An electronic database search was conducted for studies published between January 1966-May 2011. Additional articles were identified through the reference lists of reviewed papers.

REVIEW METHODS

Inclusion/exclusion criteria and quality appraisal were applied to ensure research primarily designed to study the relationship between obesity and asthma in children was included.

RESULTS

The majority of studies support a positive association between obesity and asthma in children. Among correlates recognized as important effect modifiers, gender was the most prominent, with obese girls more likely to have asthma diagnoses than obese boys. Scrutinization of covariates in selected studies revealed that most related to children's demographic characteristics and were inconsistent across the studies.

CONCLUSIONS

This review was designed to integrate contemporary scientific findings on the association between obesity and asthma by including a large number of studies with variant research designs. To identify high-risk groups and develop nursing interventions to help children affected by both epidemics, more interdisciplinary and well-designed investigations focusing on an expanded spectrum of correlates including demographic and behavioural factors are warranted.

Probiotics in the development and treatment of allergic disease

Gut microbiota composition can discriminate between allergic and healthy children, and the distinction may precede clinical manifestations of disease. The mother provides the first inoculum of bacteria, which influences the risk of becoming allergic later in life. Bifidobacterium species are major determinants of disease risk. Specific probiotics may modulate early microbial colonization, which represents the first intervention target in allergic disease, together with their ability to reverse the increased intestinal permeability characteristic of children with atopic eczema and food allergy. Probiotics also enhance gut-specific IgA responses, which are frequently defective in children with food allergy. In addition, probiotics have the potential to alleviate allergic inflammation locally and systemically.

Associations and interactions of genetic polymorphisms in innate immunity genes with early viral infections and susceptibility to asthma and asthma-related phenotypes

BACKGROUND

The innate immune system is essential for host survival because of its ability to recognize invading pathogens and mount defensive responses.

OBJECTIVES

We sought to identify genetic associations of innate immunity genes with atopy and asthma and interactions with early viral infections (first 12 months of life) in a high-risk birth cohort.

METHODS

Three Canadian family-based studies and 1 Australian population-based case-control study (n = 5565) were used to investigate associations of 321 single nucleotide polymorphisms (SNPs) in 26 innate immunity genes with atopy, asthma, atopic asthma, and airway hyperresponsiveness. Interactions between innate immunity genes and early viral exposure to 3 common viruses (parainfluenza, respiratory syncytial virus, and picornavirus) were examined in the Canadian Asthma Primary Prevention Study by using both an affected-only family-based transmission disequilibrium test and case-control methods.

RESULTS

In a joint analysis of all 4 cohorts, IL-1 receptor 2 (IL1R2) and Toll-like receptor 1 (TLR1) SNPs were associated with atopy after correction for multiple comparisons. In addition, an NFKBIA SNP was associated with atopic asthma. Six SNPs (rs1519309 [TLR3], rs740044 [ILIR2], rs4543123 [TLR1], rs5741812 [LBP], rs917998 [IL18RAP], and rs3136641 [NFKBIB]) were significant (P < .05, confirmed with 30,000 permutations) in both the combined analysis of main genetic effects and SNP-virus interaction analyses in both case-control and family-based methods. The TLR1 variant (rs4543123) was associated with both multiple viruses (respiratory syncytial virus and parainfluenza virus) and multiple phenotypes.

CONCLUSION

We have identified novel susceptibility genes for asthma and related traits and interactions between these genes and early-life viral infections.

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.

A socioecological framework to understand weight-related issues in Aboriginal children in Canada

Obesity prevention efforts in Aboriginal (First Nations, Métis, or Inuit) communities in Canada should focus predominantly on children given their demographic significance and the accelerated time course of occurrence of type 2 diabetes mellitus in the Aboriginal population. A socioecological model to address childhood obesity in Aboriginal populations would focus on the numerous environments at different times in childhood that influence weight status, including prenatal, sociocultural, family, and community environments. Importantly, for Aboriginal children, obesity interventions need to also be situated within the context of a history of colonization and inequities in the social determinants of health. This review therefore advocates for the inclusion of a historical perspective and a life-course approach to obesity prevention in Aboriginal children in addition to developing interventions around the socioecological framework. We emphasize that childhood obesity prevention efforts should focus on promoting maternal health behaviours before and during pregnancy, and on breastfeeding and good infant and child nutrition in the postpartum and early childhood development periods. Ameliorating food insecurity by focusing on improving the sociodemographic risk factors for it, such as increasing income and educational attainment, are essential. More research is required to understand and measure obesogenic Aboriginal environments, to examine how altering specific environments modifies the foods that children eat and the activities that they do, and to examine how restoring and rebuilding cultural continuity in Aboriginal communities modifies the many determinants of obesity. This research needs to be done with the full participation of Aboriginal communities as partners in the research.

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.

Systematic review and meta-analysis investigating breast feeding and childhood wheezing illness

There is conflicting evidence concerning the relationship between breast feeding and wheezing illness. The objective of this study was to investigate whether there is any association between breast feeding and wheezing in children aged over 5 years and to discover possible sources of heterogeneity. An electronic search of MEDLINE and EMBASE databases was conducted from January 2000 to June 2010. In addition, reference lists from relevant publications were searched. Birth cohort, cross-sectional and case-control studies were included if they measured any breast feeding or exclusive breast feeding for 3 or 4 months. Wheezing illness, including asthma, was identified based on symptoms, reported diagnosis or objective criteria. Thirty-one publications were identified for meta-analysis. There was no association found between any or exclusive breast feeding and wheezing illness, although there was a high level of heterogeneity between the studies. Subgroup analysis revealed that any breast feeding slightly lowers the odds of wheeze (pooled odds ratio 0.92 [0.86, 0.98]) but slightly increases the odds of asthma defined by specific criteria (pooled odds ratio 1.10 [1.00, 1.22]). This meta-analysis does not provide evidence that breast feeding is protective against wheezing illness in children aged 5 years and over. The difference in the effects of breast feeding according to the nature of the wheezing illness highlights the importance of the heterogeneity of illness phenotypes.

Body image and dieting attitudes among preadolescents

PURPOSE

Differences in body image and dieting concerns were assessed in preadolescent boys and girls across the body mass index (BMI) spectrum. The hypothesis was that girls would express more concern with body size, report more dieting, and receive more advice than boys.

METHODS

In this cross-sectional descriptive study, age-appropriate figure drawings, the Children's Eating Attitudes Test (ChEAT), the Restraint Scale, and the Body Esteem Scale were administered to participants in the Study of Asthma, Genes and Environment, Manitoba. Responses were compared between genders and correlated with BMI percentiles.

RESULTS

A total of 565 10- and 11-year-old children (321 boys) completed questionnaires. Overall, 39% of participants wanted to be thinner, and no significant gender differences based on weight were found. However, the use of figure drawings indicated that girls desired greater changes in body size (p=0.006). Girls had higher Restraint Scale scores (p=0.003), but no statistically significant differences were found in self-reported dieting, ChEAT, or Body Esteem Scale scores. Approximately 25% of children reported receiving frequent weight-related advice. Girls did not report this more often than did boys. Children in the lowest BMI percentile desired the greatest change in body shape and had the highest Restraint Scale scores.

CONCLUSIONS

Key gender differences underline the importance of understanding children's attitudes toward body image, weight, and dieting.

Overweight, asthma symptoms, atopy and pulmonary function in children of 4-12 years of age: findings from the SCAALA cohort in Salvador, Bahia, Brazil

OBJECTIVE

To evaluate the association between overweight and the occurrence of asthma and atopy in a cohort of children of 4-12 years of age living in the city of Salvador in 2005.

DESIGN

Cross-sectional study nested in a cohort.

SETTING

The metropolitan region of Salvador, Bahia, Brazil.

SUBJECTS

The study included 1129 children of 4-12 years age who presented complete information on the variables used here. Skin tests for allergy, spirometry, faecal parasitology, serum IgE and anthropometric surveys were conducted. Poisson's multivariate regression was adopted.

RESULTS

Wheezing was found in 29·1% and asthma in 22·8% of children, both conditions being more common in those under 6 years of age and 34% more common in overweight children (prevalence ratio (PR) = 1·34; 95% CI 1·07, 1·67) following adjustment. The ratio between forced expiratory volume in 1s and forced vital capacity was associated with overweight (PR = 1·35; 95% CI 1·11, 1·61). No statistically significant association was found between overweight and allergen-specific IgE or with wheezing.

CONCLUSIONS

These results are in agreement with the hypothesis that overweight is associated with asthma and pulmonary function, even following adjustment for intervening variables known to be associated with the pathogeny of asthma.

Childhood body mass index and risk of asthma in adolescence: a systematic review

Asthma and obesity, both of which are considered global health issues, affect approximately 300 million individuals worldwide. The observation that asthma and obesity tend to increase in parallel may indicate a potential link between these two conditions. The aim of this systematic review of the literature was to investigate the relationship between childhood nutritional status and incidence or persistence of asthma during adolescence. The principal eligibility criteria for selection of articles were including longitudinal analysis, and which measured of exposure during childhood or adolescence and outcome during adolescence. The systematic search initially returned 1563 unique articles. After inspection of titles and reading the abstracts of these articles, we chose 27 for full reading. Of these, 10 were selected to be included in the present review. Of the 10 selected studies, eight showed positive associations between overweight/obesity and asthma. Of these, two were independent of sex, three were found only among men and another three only among women. The present study shows strong evidence that, although the role of sex is not clear, obesity precedes, and is associated with, the persistence and intensity of symptoms of asthma.

Breast-feeding in relation to asthma, lung function, and sensitization in young schoolchildren

BACKGROUND

The evidence from previous studies on beneficial effects of breast-feeding in relation to development of asthma is conflicting.

OBJECTIVE

To investigate the relation between breast-feeding and asthma and/or sensitization during the first 8 years of life.

METHOD

In a birth cohort, children were followed up to 8 years by questionnaires at ages 2 months and 1, 2, 4, and 8 years to collect information on exposures and health effects. Determination of serum IgE antibodies to common inhalant and food allergens was performed at 4 and 8 years. Longitudinal analyses were applied by using general estimated equations. The study population consisted of 3825 children (93% of the original cohort), of whom 2370 gave blood and 2564 performed lung function measurements at 8 years.

RESULTS

Children exclusively breast-fed 4 months or more had a reduced risk of asthma during the first 8 years of life (adjusted odds ratio [OR], 0.63; 95% CI, 0.50-0.78) compared with children breast-fed less than 4 months. At 8 years, reduced risks of sensitization (adjusted OR, 0.79; 95% CI, 0.64-0.99) and asthma in combination with sensitization (adjusted OR, 0.59; 95% CI, 0.37-0.93) were seen among children exclusively breast-fed 4 months or more. This group also had a significantly better lung function measured with peak expiratory flow.

CONCLUSION

Breast-feeding for 4 months or more seems to reduce the risk of asthma up to 8 years. At this age, a reduced risk was observed particularly for asthma combined with sensitization. Furthermore, breast-feeding seems to have a beneficial effect on lung function.

Risk for asthma in offspring of asthmatic mothers versus fathers: a meta-analysis

BACKGROUND

Many human epidemiologic studies demonstrate that maternal asthma confers greater risk of asthma to offspring than does paternal disease. However, a handful have shown the opposite. Given this disparity, a meta-analysis is necessary to determine the veracity and magnitude of the "maternal effect."

METHODOLOGY/PRINCIPAL FINDINGS

We screened the medical literature from 1966 to 2009 and performed a meta-analysis to compare the effect of maternal asthma vs. paternal asthma on offspring asthma susceptibility. Aggregating data from 33 studies, the odds ratio for asthma in children of asthmatic mothers compared with non-asthmatic mothers was significantly increased at 3.04 (95% confidence interval: 2.59-3.56). The corresponding odds ratio for asthma in children of asthmatic fathers was increased at 2.44 (2.14-2.79). When comparing the odds ratios, maternal asthma conferred greater risk of disease than did paternal asthma (3.04 vs. 2.44, p = 0.037). When analyzing the studies in which asthma was diagnosed by a physician the odds ratios were attenuated and no significant differences were observed (2.85 vs. 2.48, N = 18, p = 0.37). Similarly, no significant differences were observed between maternal and paternal odds ratios when analyzing the studies in which the patient population was 5 years or older (3.15 vs. 2.60, p = 0.14). However, in all cases the trend remained the same, that maternal asthma was a greater risk factor for asthma than paternal.

CONCLUSIONS/SIGNIFICANCE

The results show that maternal asthma increases offspring disease risk to a greater extent than paternal disease.

Children's Perceptions of Healthful Eating and Physical Activity

Purpose: Healthful lifestyle habits established in childhood may continue through adulthood. Such habits may also be effective in preventing or reversing overweight and obesity. However, little is known about children's perceptions of healthful eating and physical activity. Thus, we sought a better understanding of how children perceive healthful eating and physical activity.

Methods: A purposeful selection was made of Winnipeg, Manitoba, boys (n=23) and girls (n=22) aged 11 to 12 years. The children were interviewed using a semi-structured, indepth interview guide. Data were analyzed using thematic coding.

Results: Although healthful eating was seen as necessary for health, high-fat, high-sugar foods were a source of pleasure and enjoyed during social times. Physical activity was a way of spending time with friends, either through active play or watching sports. Boys viewed screen time and homework as barriers to physical activity, while girls identified no common barriers. Children viewed physical activity as easier than healthful eating, describing the former as “play” and “fun.”

Conclusions: Knowing how children think about food choices will further our understanding of the disconnect between nutrition knowledge and dietary behaviours. Understanding conflicting pressures that influence children's healthful lifestyles may enhance communication about these topics among parents, educators, and children.

Lower cortisol levels in children with asthma exposed to recurrent maternal distress from birth

BACKGROUND

Existing evidence supports associations between exposure to maternal distress and the development of childhood asthma, between exposure to maternal distress and an increased cortisol response in children, and between childhood asthma and an attenuated cortisol response.

OBJECTIVE

To investigate the association between children's cortisol levels and the combined predictors of exposure to maternal distress and childhood asthma.

METHODS

Serum cortisol levels were examined at age 7 to 10 years in relation to asthma status and exposure to maternal distress in a representative sample of children (n = 503) born in 1995. Data from health care and prescription databases were linked with additional data collected in this longitudinal study. Maternal distress was defined as a physician diagnosis of a depressive or anxiety disorder or a prescription history of related medications as reported in the mothers' health care records. Children's asthma status was determined via examination by 2 pediatric allergists.

RESULTS

A multiple linear regression analysis revealed that exposure to maternal distress restricted to the first year of life predicted elevated cortisol levels in children, regardless of asthma status (>40% increase). A significant interaction was discovered in the group of children exposed to maternal distress extending beyond the postnatal period such that no asthma predicted a 25.9% increase in cortisol and a diagnosis of asthma predicted a 5.2% decrease in cortisol. Cortisol levels were further lowered in atopic and bronchial hyperresponsive asthma.

CONCLUSION

Among children exposed to recurrent maternal distress, an elevation in cortisol levels occurs in response to an acute stressor when there is no accompanying diagnosis of asthma, whereas, in comparison, children with asthma tend to exhibit lower cortisol levels.

A novel study design to investigate the early-life origins of asthma in children (SAGE study)

This is a description of the Study of Asthma, Genes and the Environment (SAGE), a novel birth cohort created from provincial healthcare administrative records. It is a general population-based cohort, composed of children at high and low risk for asthma, living in urban and rural environments in Manitoba, Canada. The SAGE study captures the complete longitudinal healthcare records of children born in 1995 and contains detailed information on early-life exposures, such as antibiotic utilization and immunization, in relationship to the development of asthma. Nested within the birth cohort is a case-control study, which was created to collect information on home environmental exposures from detailed surveys and home dust sampling, to confirm asthma status in children and use this data to validate healthcare database measures of asthma, to determine differences in immune system responsiveness to innate and adaptive immune stimuli in asthma, to genotype children for genes likely associated with the development of asthma and to study the epigenetic regulation of pre-established protective vs allergic immune responses. The SAGE study is a multidisciplinary collaboration of researchers from pediatric allergy, population health, immunology, and genetic and environmental epidemiology. As such, it serves as a fertile, interdisciplinary training ground for graduate students, and postdoctoral and clinician fellows.

A thymic stromal lymphopoietin gene variant is associated with asthma and airway hyperresponsiveness

BACKGROUND

The epithelial cell-derived protein thymic stromal lymphopoietin stimulates dendritic and mast cells to promote proallergic T(H)2 responses. Studies of transgenic expression of thymic stromal lymphopoietin and its receptor knockout mice have emphasized its critical role in the development of allergic inflammation. Association of genetic variation in thymic stromal lymphopoietin with IgE levels has been reported for human subjects.

OBJECTIVE

The aim of this study was to evaluate the relationship between variants of thymic stromal lymphopoietin and asthma and related phenotypes.

METHODS

We selected 6 single nucleotide polymorphisms in thymic stromal lymphopoietin and genotyped 5565 individuals from 4 independent asthma studies and tested for association with asthma, atopy, atopic asthma, and airway hyperresponsiveness by using a general allelic likelihood ratio test. P values were corrected for the effective number of independent single nucleotide polymorphisms and phenotypes.

RESULTS

The A allele of rs1837253, which is 5.7 kb upstream of the transcription start site of the gene, was associated with protection from asthma, atopic asthma, and airway hyperresponsiveness, with the odds ratios and corrected P values for each being 0.79 and 0.0058; 0.75 and 0.0074; and 0.76 and 0.0094, respectively. Associations between thymic stromal lymphopoietin and asthma-related phenotypes were the most statistically significant observations in our study, which has to date examined 98 candidate genes. Full results are available online at http://genapha.icapture.ubc.ca/.

CONCLUSIONS

A genetic variant in the region of the thymic stromal lymphopoietin gene is associated with the phenotypes of asthma and airway hyperresponsiveness.

Continuation of breastfeeding: is this a problem in Southeast Iran?

BACKGROUND

Despite widespread knowledge about breastfeeding benefits for mothers and neonates, duration of breastfeeding is decreasing in most countries. Many factors have an effect on continuation of breastfeeding. This study was designed to evaluate duration of breastfeeding and its associated factors in rural and urban children.

METHODS

In a historical cohort study, health files of 1,264 Iranian children under 3 years old were selected by the multistage sampling method in the Zabol district, located in southeast Iran. Two lists of rural and urban health centers based on their distance were prepared, and by systematic sampling technique three centers were selected in each list. Tables, Kaplan-Meier analysis, and median and mean O SD values were used for data description; log-rank test and the Cox proportional hazard model were applied for data analysis.

RESULTS

The mean duration of exclusive breastfeeding was 5.6 +/- 1.3 months, and the mean duration of any breastfeeding was 20.8 +/- 4.69 months. All children had started breastfeeding at birth. Breastfeeding continuation at 6, 12, 18, and 24 months was 98%, 92%, 76%, and 0.97%, respectively. Maternal age, mother's job, education level, living area, child's birth weight, child's birth rank, birth intervals, and age of onset of supplementary food had a significant relationship with breastfeeding continuation.

CONCLUSIONS

Some risk factors for breastfeeding continuation were found, and it is suggested that more attention be paid to them in education programs by the health system.

Does leptin play a role in obesity-asthma relationship?

The increase of asthma has paralleled the rising obesity during the past decades. Obesity is characterized by the increase of leptin in the circulation. Leptin is an obesity gene product, and it can stimulate the production of pro-inflammatory mediators, such as tumor necrosis factor (TNF)-alpha, interleukin (IL)-6 and interferon (IFN)-gamma. There is a link between leptin and asthma, especially in children. It remains unclear however, if leptin is in the pathway of obesity-asthma relationship and if it plays a distinctive role in asthma in obese vs. non-obese subjects. Since leptin is in a positive feedback loop with the pro-inflammatory cytokines such as TNF-alpha, there is a possibility that leptin is involved as a regulatory rather than an etiologic mechanism of asthma development. Weight loss is associated with decreased circulating leptin concentration in children. Weight control program may need to be considered in the treatment of asthma in obese children.

An interdisciplinary analysis of sex and gender in relation to the pathogenesis of bronchial asthma

BACKGROUND

An increasing number of studies confirm that pathogenesis and prevalence of bronchial asthma are age and sex dependent. Detailed physiological mechanisms of the changing sex ratios with age are not fully known, however, the gender (socio-cultural) factors are also imperative. Although multiple factors definitely influence the pathogenesis of asthma, only individual or few combinations of these have been investigated.

METHODS

The terms 'sex', 'gender' and plausible combinations of both were systematically researched in selected databases (Medline, Scopus) or other sources, including publications from January 2000 to June 2007. Generated articles were categorized, either as endogenous or exogenous factors influencing the pathogenesis of asthma, and divided into the following subgroups: genetic, immunological, hormonal, gynaecological, nutritional, and environmental parameters.

RESULTS

An increasing number of studies investigate the influence of sex and gender in the aetiology, therapy and prevention of asthma. While their results are still debatable, others regarding its initiation, perpetuation and cessation have been clarified. Recent insights into interactions at biomolecular and immunological levels greatly contribute to clarifying sex-specific influences. Despite occasional oversimplifications, a trend for explanations considering the complex interplay of different factors can be observed. This work is in line with this trend and offers explanation models from our point of view.

CONCLUSIONS

Some disagreements regarding the patho-physiology, diagnosis, treatment and prevention of asthma still prevail. Nevertheless, in order to better appreciate its complexity, openness to and persistent consideration for interdisciplinary as well as sex- and gender-related factors is required of the medical-research community in future investigations.

Fast food consumption counters the protective effect of breastfeeding on asthma in children?

BACKGROUND

Fast food consumption and childhood asthma have rapidly increased in recent decades. During the same period there has been an increased rate of prolonged breastfeeding.

OBJECTIVE

To evaluate if fast food consumption was associated with asthma in children, and if the proposed protective effect of breastfeeding on asthma was altered by fast food consumption.

METHODS

This case-control study included 246 children with allergist-diagnosed asthma and 477 non-asthmatic controls at age 8-10 years. Information on fast food consumption and exclusive breastfeeding was obtained from questionnaire data. The association between asthma and fast food consumption was evaluated. Asthma in relation to exclusive breastfeeding was also evaluated, taking into account fast food consumption as a modifying factor.

RESULTS

Children with asthma were more likely to consume fast food than children without asthma [crude odds ratio (OR) 1.70, 95% confidence interval (CI) 1.23-2.34]. In comparison to prolonged exclusive breastfeeding (> or =12 weeks), asthma was positively associated with short-term exclusive breastfeeding (<12 weeks) in children who never or occasionally consumed fast food (crude OR 1.84, 95% CI 1.09-3.11), but not in children who frequently consumed fast food (crude OR 1.07, 95% CI 0.72-1.61). The P-value for this interaction (0.109) was borderline. Children with high fast food consumption who were exclusively breastfed <12 weeks as infants, had greater than a twofold risk of asthma compared with infants who had been exclusively breastfed for a longer time period and who did not become high consumers of fast food in later childhood. These findings were not affected after final adjustment of confounders and covariates.

CONCLUSION

Fast food consumption is associated with asthma in children and potentially counteracts the protective effect of prolonged breastfeeding on asthma. This may explain the paradoxical phenomenon of parallel increased rates of prolonged breastfeeding and asthma in children. 556-561.

Normalization strategies of children with asthma

Despite understanding the physiologic effects of childhood asthma, less is known about how children perceive living with asthma. We undertook semistructured, in-depth interviews with 11 boys and 11 girls (all aged 11) drawn from a larger ongoing asthma study of Manitoba children born in 1995. All had asthma, as diagnosed by a pediatric allergist. We sought to further understand how children perceive asthma. Children spoke of feeling different and commonly used words such as "pain" and "hurt." We have categorized children's strategies to normalize their lives as (a) minimizing the health impact, (b) stressing normality, (c) emphasizing abilities, (d) making adaptations in daily living, and, (e) managing symptoms with medications. These findings suggest that aspects of other researchers' work regarding normalization efforts of children with various chronic diseases also apply in a chronic condition that is less obvious.

Breastfeeding and allergies: time for a change in paradigm?

PURPOSE OF REVIEW

This review examines recent studies of the relationships between breastfeeding and the epidemiology of allergic diseases, especially atopic dermatitis in infants and asthma in early and later childhood.

RECENT FINDINGS

Results from observational birth cohort studies, case-control studies, and one cluster randomized intervention trial have generally failed to demonstrate a protective effect of breastfeeding on outcomes of atopic dermatitis, allergic sensitization, wheezing, or asthma. Difficulties in interpretation relate to the absence of nonbreastfed control or reference groups in some studies, meaning outcomes can only be compared between different durations of breastfeeding. Studies with a nonbreastfed control group suggest there is an increased risk for atopy and asthma associated with breastfeeding and that prolonged breastfeeding may eventually reduce this increased risk. The family history, sex of the child, and the presence of other risk factors for allergy and asthma also influence the outcome.

SUMMARY

Although breastfeeding is strongly recommended for its multiple benefits on child health, most recent studies do not confirm the 'conventional wisdom' that breastfeeding is protective against allergy and asthma. Early reduction in childhood wheezing may reflect protection from viral infections, but allergies and asthma at later ages may be increased.

Primary asthma prevention: is it possible?

Asthma, which typically begins in childhood and is the most common chronic disease of childhood, has reached epidemic proportions. Asthma is associated with gene-environment interactions, and there is consensus that a "window of opportunity" exists early in life when environmental factors may influence its development. This review considers biologic and sociologic factors in the development of allergy and asthma. Meta-analysis of studies demonstrates that monoallergen reduction does not impact asthma prevention. However, multifaceted allergen reduction studies have shown clinical benefit. We propose that allergic diseases, including asthma, represent a dysfunctional interaction with our environment and that the increasing prevalence of asthma and allergy herald increased population risk for the development of other inflammatory and autoimmune diseases. Better understanding of the complex factors for asthma and allergies may provide insight into many other chronic complex diseases.

Advances in pediatric asthma in 2007

This year's summary focuses on recent advances in pediatric asthma as reported in 2007 publications in the Journal. This past year, new National Asthma Education and Prevention Program asthma guidelines were released with a special emphasis on new information in pediatric asthma. Journal theme issues in 2007 included the revised National Asthma Education and Prevention Program asthma guidelines, the accomplishments of the National Institutes of Health asthma networks, and focused discussions on environmental allergens, neutrophils, eosinophils, T cells, and epithelial cells, all of which affect pediatric asthma. The new asthma guidelines emphasize several key terms including severity, control, impairment, risk, and responsiveness that are relevant for advancing the care of children with asthma. This review highlights journal articles that relate to these guideline topics.