Does breast feeding help protect against atopic disease? Biology, methodology, and a golden jubilee of controversy

Exclusive breast-feeding, the early-life microbiome and immune response, and common childhood respiratory illnesses

BACKGROUND

The impact of breast-feeding on certain childhood respiratory illnesses remains controversial.

OBJECTIVE

We sought to examine the effect of exclusive breast-feeding on the early-life upper respiratory tract (URT) and gut microbiome, the URT immune response in infancy, and the risk of common pediatric respiratory diseases.

METHODS

We analyzed data from a birth cohort of healthy infants with prospective ascertainment of breast-feeding patterns and common pediatric pulmonary and atopic outcomes. In a subset of infants, we also characterized the URT and gut microbiome using 16S ribosomal RNA sequencing and measured 9 URT cytokines using magnetic bead-based assays.

RESULTS

Of the 1949 infants enrolled, 1495 (76.71%) had 4-year data. In adjusted analyses, exclusive breast-feeding (1) had an inverse dose-response on the ⍺-diversity of the early-life URT and gut microbiome, (2) was positively associated with the URT levels of IFN-α, IFN-γ, and IL-17A in infancy, and (3) had a protective dose-response on the development of a lower respiratory tract infection in infancy, 4-year current asthma, and 4-year ever allergic rhinitis (odds ratio [95% CI] for each 4 weeks of exclusive breast-feeding, 0.95 [0.91-0.99], 0.95 [0.90-0.99], and 0.95 [0.92-0.99], respectively). In exploratory analyses, we also found that the protective association of exclusive breast-feeding on 4-year current asthma was mediated through its impact on the gut microbiome (P = .03).

CONCLUSIONS

Our results support a protective causal role of exclusive breast-feeding in the risk of developing a lower respiratory tract infection in infancy and asthma and allergic rhinitis in childhood. They also shed light on potential mechanisms of these associations, including the effect of exclusive breast-feeding on the gut microbiome.

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.

Breastfeeding and risk of childhood asthma: a systematic review and meta-analysis

OBJECTIVE

To investigate the relationship between breastfeeding and the development of paediatric asthma.

METHODS

A systematic review and meta-analysis was conducted with MEDLINE, Embase, CINAHL and ProQuest Nursing and Allied Health source databases. Retrospective/prospective cohorts in children aged <18 years with breastfeeding exposure reported were included. The primary outcome was a diagnosis of asthma by a physician or using a guideline-based criterion. A secondary outcome was asthma severity.

RESULTS

42 studies met inclusion criteria. 37 studies reported the primary outcome of physician-/guideline-diagnosed asthma, and five studies reported effects on asthma severity. Children with longer duration/more breastfeeding compared to shorter duration/less breastfeeding have a lower risk of asthma (OR 0.84, 95% CI 0.75-0.93; I2 = 62.4%). Similarly, a lower risk of asthma was found in children who had more exclusive breastfeeding versus less exclusive breastfeeding (OR 0.81, 95% CI 0.72-0.91; I2=44%). Further stratified analysis of different age groups demonstrated a lower risk of asthma in the 0-2-years age group (OR 0.73, 95% CI 0.63-0.83) and the 3-6-years age group (OR 0.69, 95% CI 0.55-0.87); there was no statistically significant effect on the ≥7-years age group.

CONCLUSION

The findings suggest that the duration and exclusivity of breastfeeding are associated with a lower risk of asthma in children aged <7 years.

Immunologically Active Components in Human Milk and Development of Atopic Disease, With Emphasis on Food Allergy, in the Pediatric Population

Breast-feeding is currently recommended to prevent the development of allergic diseases; however, data are conflicting and mechanisms are unclear. The immunomodulatory composition of human milk is poorly characterized and varies between mothers. We and others have shown that high levels of human milk IgA and certain cytokines and human milk oligosaccharides are associated with protection against food allergy in the infant, but it is unclear whether they are responsible for or simply biomarkers of the vertical transfer of protection. Because human milk has pre- and probiotic properties, the anti-allergy protection afforded by human milk may be due to its control on the developing gut microbiome. In mice, murine milk IgA supports gut homeostasis and shapes the microbiota, which in turn diversifies the intestinal IgA repertoire that reciprocally promotes the diversity of gut microbiome; these mechanisms are poorly understood in humans. In addition, several human milk bioactives are immunostimulatory, which may in part provide protection against allergic diseases. The regulation of immunologically active components in human milk is incompletely understood, although accumulating evidence suggests that IgA and cytokines in human milk reflect maternal exposures. This review summarizes the current literature on human milk components that have been associated with protection against food allergy and related allergic disorders in early childhood and discusses the work relating to regulation of these levels in human milk and possible mechanisms of action.

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.

Human Milk and Allergic Diseases: An Unsolved Puzzle

There is conflicting evidence on the protective role of breastfeeding in relation to the development of allergic sensitisation and allergic disease. Studies vary in methodology and definition of outcomes, which lead to considerable heterogeneity. Human milk composition varies both within and between individuals, which may partially explain conflicting data. It is known that human milk composition is very complex and contains variable levels of immune active molecules, oligosaccharides, metabolites, vitamins and other nutrients and microbial content. Existing evidence suggests that modulation of human breast milk composition has potential for preventing allergic diseases in early life. In this review, we discuss associations between breastfeeding/human milk composition and allergy development.

Breastfeeding, maternal asthma and wheezing in the first year of life: a longitudinal birth cohort study

The impact of breastfeeding on respiratory health is uncertain, particularly when the mother has asthma. We examined the association of breastfeeding and wheezing in the first year of life.We studied 2773 infants from the Canadian Healthy Infant Longitudinal Development (CHILD) birth cohort. Caregivers reported on infant feeding and wheezing episodes at 3, 6 and 12 months. Breastfeeding was classified as exclusive, partial (supplemented with formula or complementary foods) or none.Overall, 21% of mothers had asthma, 46% breastfed for at least 12 months and 21% of infants experienced wheezing. Among mothers with asthma, breastfeeding was inversely associated with infant wheezing, independent of maternal smoking, education and other risk factors (adjusted rate ratio (aRR) 0.52; 95% CI 0.35-0.77 for ≥12 versus <6 months breastfeeding). Compared with no breastfeeding at 6 months, wheezing was reduced by 62% with exclusive breastfeeding (aRR 0.38; 95% CI 0.20-0.71) and by 37% with partial breastfeeding supplemented with complementary foods (aRR 0.63; 95% CI 0.43-0.93); however, breastfeeding was not significantly protective when supplemented with formula (aRR 0.89; 95% CI 0.61-1.30). Associations were not significant in the absence of maternal asthma (p-value for interaction <0.01).Breastfeeding appears to confer protection against wheezing in a dose-dependent manner among infants born to mothers with asthma.

Prevention of food and airway allergy: consensus of the Italian Society of Preventive and Social Paediatrics, the Italian Society of Paediatric Allergy and Immunology, and Italian Society of Pediatrics

BACKGROUND

Allergic sensitization in children and allergic diseases arising therefrom are increasing for decades. Several interventions, functional foods, pro- and prebiotics, vitamins are proposed for the prevention of allergies and they can't be uncritically adopted.

OBJECTIVE

This Consensus document was developed by the Italian Society of Preventive and Social Paediatrics and the Italian Society of Paediatric Allergy and Immunology. The aim is to provide updated recommendations regarding allergy prevention in children.

METHODS

The document has been issued by a multidisciplinary expert panel and it is intended to be mainly directed to primary care paediatricians. It includes 19 questions which have been preliminarily considered relevant by the panel. Relatively to each question, a literature search has been performed, according to the Italian National Guideline Program. Methodology, and a brief summary of the available literature data, has been provided. Many topics have been analyzed including the role of mother's diet restriction, use of breast/formula/hydrolyzed milk; timing of introduction of complementary foods, role (if any) of probiotics, prebiotics, vitamins, exposure to dust mites, animals and to tobacco smoke.

RESULTS

Some preventive interventions have a strong level of recommendation. (e.g., the dehumidifier to reduce exposure to mite allergens). With regard to other types of intervention, such as the use of partially and extensively hydrolyzed formulas, the document underlines the lack of evidence of effectiveness. No preventive effect of dietary supplementation with polyunsaturated fatty acids, vitamins or minerals has been demonstrated. There is no preventive effect of probiotics on asthma, rhinitis and allergic diseases. It has demonstrated a modest effect, but steady, in the prevention of atopic dermatitis.

CONCLUSIONS

The recommendations of the Consensus are based on a careful analysis of the evidence available. The lack of evidence of efficacy does not necessarily imply that some interventions may not be effective, but currently they can't be recommended.

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 Risk of Kawasaki Disease: A Nationwide Longitudinal Survey in Japan

BACKGROUND AND OBJECTIVES

Kawasaki disease (KD) is the most common cause of childhood-acquired heart disease in developed countries. However, the etiology of KD is not known. Aberrant immune responses are considered to play key roles in disease initiation and breastfeeding can mature immune system in infants. We thus examined the association between breastfeeding and the development of KD.

METHODS

We used a nationwide population-based longitudinal survey ongoing since 2010 and restricted participants to a total of 37 630 children who had data on their feeding during infancy. Infant feeding practice was queried at 6 to 7 months of age, and responses to questions about hospital admission for KD during the period from 6 to 30 months of age were used as outcome. We conducted logistic regression analyses controlling for child and maternal factors with formula feeding without colostrum as our reference group.

RESULTS

A total of 232 hospital admissions were observed. Children who were breastfed exclusively or partially were less likely to be hospitalized for KD compared with those who were formula fed without colostrum; odds ratios for hospitalization were 0.26 (95% confidence interval: 0.12-0.55) for exclusive breastfeeding and 0.27 (95% confidence interval: 0.13-0.55) for partial breastfeeding. Although the risk reduction was not statistically significant, feeding colostrum only also provided a protective effect.

CONCLUSIONS

We observed protective effects of breastfeeding on the development of KD during the period from 6 to 30 months of age in a nationwide, population-based, longitudinal survey in Japan, the country in which KD is most common.

Factors affecting breast milk composition and potential consequences for development of the allergic phenotype

There is conflicting evidence on the protective role of breastfeeding in relation to allergic sensitization and disease. The factors in breast milk which influence these processes are still unclear and under investigation. We know that colostrum and breast milk contain a variety of molecules which can influence immune responses in the gut-associated lymphoid tissue of a neonate. This review summarizes the evidence that variations in colostrum and breast milk composition can influence allergic outcomes in the infant, and the evidence that maternal and environmental factors can modify milk composition. Taken together, the data presented support the possibility that maternal dietary interventions may be an effective way to promote infant health through modification of breast milk composition.

The impact of diet on asthma and allergic diseases

The incidence of allergic diseases is increasing, both in developed and developing countries, concomitantly with the rise in living standards and the adoption of a 'western lifestyle'. For two decades, the hygiene hypothesis - which proposes that the lack of early childhood exposure to infectious agents increases susceptibility to allergic diseases in later life - provided the conceptual framework for unravelling the mechanisms that could account for the increased incidence of allergic diseases. In this Review, we discuss recent evidence that highlights the role of diet as a key factor influencing immune homeostasis and the development of allergic diseases through a complex interplay between nutrients, their metabolites and immune cell populations. Although further investigations are still required to understand these complex relationships, recent data have established a possible connection between metabolic homeostasis and allergic diseases.

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.

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.

Cohort profile: The promotion of breastfeeding intervention trial (PROBIT)

The PROmotion of Breastfeeding Intervention Trial (PROBIT) is a multicentre, cluster-randomized controlled trial conducted in the Republic of Belarus, in which the experimental intervention was the promotion of increased breastfeeding duration and exclusivity, modelled on the Baby-friendly hospital initiative. Between June 1996 and December 1997, 17,046 mother-infant pairs were recruited during their postpartum hospital stay from 31 maternity hospitals, of which 16 hospitals and their affiliated polyclinics had been randomly assigned to the arm of PROBIT investigating the promotion of breastfeeding and 15 had been assigned to the control arm, in which breastfeeding practices and policies in effect at the time of randomization was continued. Of the mother-infant pairs originally recruited for the study, 16,492 (96.7%) were followed at regular intervals until the infants were 12 months of age (PROBIT I) for the outcomes of breastfeeding duration and exclusivity; gastrointestinal and respiratory infections; and atopic eczema. Subsequently, 13,889 (81.5%) of the children from these mother-infant pairs were followed-up at age 6.5 years (PROBIT II) for anthropometry, blood pressure (BP), behaviour, dental health, cognitive function, asthma and atopy outcomes, and 13,879 (81.4%) children were followed to the age of 11.5 years (PROBIT III) for anthropometry, body composition, BP, and the measurement of fasted glucose, insulin, adiponectin, insulin-like growth factor-I, and apolipoproteins. The trial registration number for Current Controlled Trials is ISRCTN37687716 and that for ClinicalTrials.gov is NCT01561612. Proposals for collaboration are welcome, and enquires about PROBIT should be made to an executive group of the study steering committee (M.S.K., R.M.M., and E.O.). More information, including information about how to access the trial data, data collection documents, and bibliography, is available at the trial website (http://www.bristol.ac.uk/social-community-medicine/projects/probit/).

Breastfeeding: Nature's Safety Net

Breastfeeding is a natural safety-net for the first few months in order to give the child a fairer start to life. The American Academy of Pediatric Dentistry recognizes the distinct nutritional advantages of human milk for infants and endorsed the position of the American Academy of Pediatrics on the promotion of breastfeeding. It therefore calls for increase in need to negotiate the roles and responsibilities of pediatric dentists to eliminate the existing gaps in preventive care and anticipatory guidance. The objective of this evidence-based review is to explore the beneficial roles of breastfeeding in orofacial growth and development and endorse the same through anticipatory guidance.

How to cite this article: Agarwal M, Ghousia S, Konde S, Raj S. Breastfeeding: Nature’s Safety Net. Int J Clin Pediatr Dent 2012;5(1):49-53.

Breastfeeding and allergy: the evidence

Whether breastfeeding protects against the development of allergic disease has been a frequent subject of study and debate for 75 years. This paper summarizes the published evidence concerning the risks of atopic dermatitis, asthma, allergic rhinitis, positive allergen skin tests, and food allergy associated with infant feeding. The summary is based largely on systematic reviews and meta-analyses carried out by other authors. In addition, I also incorporate the evidence from our long-term follow-up of Belarusian children participating in a cluster-randomized trial of a breastfeeding promotion intervention.

The evidence for public health recommendations on infant feeding

Public health recommendations should be based on the best available scientific evidence, and this necessitates careful appraisal of the available data and management of scientific uncertainty. This paper discusses the difficulties in collecting and interpreting scientific data on infant feeding, in particular the fact that since it is not feasible to randomise healthy infants to be breast or formula-fed, the majority of available data come from observational studies with associated methodological limitations. The scientific evidence available to underpin recommendations for breastfeeding and for 6months exclusive breastfeeding are presented in the context of these limitations, noting disagreement between expert groups considering the same scientific data. Finally, the use of science to formulate infant feeding recommendations, and communication of information, including scientific uncertainty, to parents are discussed.

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.

DHA supplementation during pregnancy and lactation affects infants' cellular but not humoral immune response

Background. It is currently recommended that diet of pregnant mothers contain 200–300 mg DHA/day. Aim. To determine whether DHA supplementation during pregnancy and lactation affects infants' immune response. Methods. 60 women in ≥3rd pregnancy studied; 30 randomly assigned to receive DHA 400 mg/day from 12th week gestation until 4 months postpartum. From breast-fed infants, blood obtained for anti-HBs antibodies, immunoglobulins, lymphocyte subset phenotyping, and intracellular cytokine production. Results. CD4+ lymphocytes did not differ between groups, but CD4CD45RA/CD4 (naïve cells) significantly higher in infants in DHA+ group. Proportion of CD4 and CD8 cells producing IFN_γ significantly lower in DHA+ group, with no differences in proportion of IL4-producing cells. Immunoglobulins and anti-HBs levels did not differ between groups. Conclusions. In infants of mothers receiving DHA supplementation, a higher percentage of CD4 naïve cells and decreased CD4 and CD8 IFN_γ production is compatible with attenuation of a proinflammatory response.

Fatty acids in breast milk and development of atopic eczema and allergic sensitisation in infancy

BACKGROUND

One of the explanations for the increasing prevalence of atopic diseases is a relative low perinatal supply of n-3 fatty acids. However, this does not explain the protective effects of whole-fat dairy products or high levels of transfatty acids in breast milk, observed in some studies. We evaluated the role of perinatal supply of fatty acids in the early development of atopic eczema and allergic sensitisation.

METHODS

Fatty acids, including n-3 long-chain polyunsaturated fatty acids (LCPs) as well as ruminant fatty acids (rumenic acid, cis-9,trans-11-C18:2 conjugated linoleic acid; and vaccenic acid, trans-11-C18:1), were determined in breast milk sampled at 1 month postpartum from 310 mother-infant pairs in the KOALA Birth Cohort Study, the Netherlands. Children were followed for atopic outcomes until 2 years of age.

RESULTS

Higher concentrations of n-3 LCPs as well as ruminant fatty acids were associated with lower risk of (1) parent-reported eczema, (2) atopic dermatitis (UK Working Party criteria), and (3) sensitisation at age 1 year (as revealed by specific serum IgE levels to cow's milk, hen's egg and/or peanut). In multivariable logistic regression analysis, the inverse associations between ruminant fatty acid concentrations in breast milk and atopic outcomes were found to be independent from n-3 LCPs.

CONCLUSIONS

The results confirm a protective role of preformed n-3 LCPs in the development of atopic disease. Moreover, this is the first study in humans confirming results from animal studies of protective effects of ruminant fatty acids against the development of atopic manifestations.

Chronic disease and infant nutrition: is it significant to public health?

OBJECTIVE

To assess the public health significance of premature weaning of infants from breast milk on later-life risk of chronic illness.

DESIGN

A review and summary of recent meta-analyses of studies linking premature weaning from breast milk with later-life chronic disease risk is presented followed by an estimation of the approximate exposure in a developed Western country, based on historical breast-feeding prevalence data for Australia since 1927. The population-attributable proportion of chronic disease associated with current patterns of artificial feeding in infancy is estimated.

RESULTS

After adjustment for major confounding variables, current research suggests that the risks of chronic disease are 30-200 % higher in those who were not breast-fed compared to those who were breast-fed in infancy. Exposure to premature weaning ranges from 20 % to 90 % in post-World War II age cohorts. Overall, the attributable proportion of chronic disease in the population is estimated at 6-24 % for a 30 % exposure to premature weaning.

CONCLUSIONS

Breast-feeding is of public health significance in preventing chronic disease. There is a small but consistent effect of premature weaning from breast milk in increasing later-life chronic disease risk. Risk exposure in the Australian population is substantial. Approximately 90 % of current 35-45-year-olds were weaned from breast-feeding by 6 months of age. Encouraging greater duration and exclusivity of breast-feeding is a potential avenue for reducing future chronic disease burden and health system costs.

[Influence of breastfeeding and diet in the development of allergies in children]

OBJECTIVE

To evaluate the relationship between breastfeeding and the development of allergic diseases (AD).

DESIGN

A cases-controls study.

SETTING

Santander University Hospital, Bucaramanga, Colombia, South America. Level II health care.

PARTICIPANTS

A total of 1460 boys and girls between 3 and 7 years old attending an outpatient clinic.

MAIN MEASUREMENTS

Partial (BF) and exclusive breastfeeding (EBF); relationship between the presence of allergic diseases and BF and EBF, adjusting for the confounding factors due to other exposures using logistic regression.

RESULTS

Out of a total of 1460 patients, 41.6% (95%CI 39.0-44.2) received EBF, while 44.4% (95%CI 41.9-47.0) were partially breastfed. Among those who had an allergy, 34.8% (95%CI 32.4-37.3) had rhinitis, 27.8% (95%CI 25.6-30.2) asthma and 11.6% (95%CI 10.0-13.4) atopic dermatitis; 7.0% (95%CI 5.1-9.3) had the three conditions. To breastfeed exclusively for >or= 3 months is a protective factor for AD (OR 0.70, 95%CI 0.48-1.03). Breastfeeding for 3 months, regardless of whether or not it is exclusive, is a risk factor for AD (OR 2.05, 95%CI 1.47-2.86).

CONCLUSIONS

The recommendation to exclusively breastfeed for as long as possible continues to be valid, as there was a significant preventive impact on the development of AD with the length of time breastfed. Prospective studies including lung function tests and immunological analyses need to be performed to confirm these findings.

The long-term effects of breastfeeding on asthma and atopic disease

In this review, the primary objective is to assess the evidence of whether breastfeeding protects against asthma and atopic disease for the long-term (long-term is defined here as >5 years of age). Two main types of observational epidemiological studies have been used to test this hypothesis. These are cohort studies of random samples of children and cohort studies of children with a family history of asthma or atopy. In each study type, exposure and outcome data are collected either prospectively or retrospectively. The 12 criteria for assessing the adequate measurement of exposure, outcome and statistics of cohort studies in this context are given in Table 17-1.

Breastfeeding and prevalence of allergic diseases in Japanese university students

BACKGROUND

Although historical support exists for the concept that breastfeeding might be protective against allergic diseases, contradictory findings have been observed recently.

OBJECTIVE

To investigate the cumulative prevalence of allergic diseases in Japanese university students and to identify explanatory variables including breastfeeding.

METHODS

From March 18, 2003, through March 29, 2005, a total of 9,615 students newly enrolled at the University of Tokyo responded to a written questionnaire on allergic diseases.

RESULTS

Cumulative prevalence of allergic rhinitis, atopic dermatitis, and asthma was 47.2%, 17.4%, and 9.3%, respectively. These data were closely correlated, and prevalence of any 1 of the 3 diseases significantly increased the odds for historical prevalence of the other 2 (P < .001). Male sex (odds ratio [OR], 1.5; 95% confidence interval [CI], 1.4-1.7) and maternal (OR, 2.2; 95% CI, 2.0-2.5) or paternal (OR, 1.6; 95% CI, 1.4-1.8) history of allergic rhinitis were significant correlates of increased odds for allergic rhinitis. Maternal (OR, 2.7; 95% CI, 1.6-4.5), paternal (OR, 3.8; 95% CI, 2.2-6.6), or sibling (OR, 1.9; 95% CI, 1.5-2.4) history of atopic dermatitis was a significant correlate of increased odds for atopic dermatitis. As for asthma, maternal (OR, 4.9; 95% CI, 3.0-7.9), paternal (OR, 4.0; 95% CI, 2.3-7.0), or sibling (OR, 3.3; 95% CI, 2.4-4.5) history of asthma was a significant correlate of increased odds. Logistic regression analysis showed no consistent evidence of the effects of breastfeeding on the cumulative prevalence.

CONCLUSION

The cumulative prevalence of these diseases among young adults revealed that the effect of breastfeeding is negligible when compared with genetic factors.

Food allergy overview in children

Food allergies have increased significantly in the past decade. An accurate history is crucial in approaching the management. At the outset, food intolerance must be distinguished from food allergies and, furthermore, these allergies should be classified into either an IgE, Non-IgE, or a mixed response. The clinical features vary from life-threatening anaphylaxis to milder IgE-mediated responses, atopic dermatitis, and gastrointestinal symptoms. The severity of the reaction and the potential risk for anaphylaxis on reexposure should be assessed. Milk, soy, egg, wheat, and peanut allergies are common in children, whereas peanut, tree nut, fish, shell fish allergies, and allergies to fruits and vegetables are common in adults. Structural proteins are important determinants of the severity of the reactions and may often predict the natural history and cross reactivity. Diagnostic work up must be guided by the clinical history. Skin testing and food-specific IgE done by standard methods are very useful, whereas oral challenges may be indicated in some situations. Majority of the patients outgrow their allergies to milk, soy, egg, and wheat, and some to peanut also, therefore, patients should be periodically reassessed. Novel diagnostic techniques which detect specific allergenic epitopes have been developed. Several newer therapies are promising.

Differential gender response to respiratory infections and to the protective effect of breast milk in preterm infants

OBJECTIVE

The protective role of breastfeeding against severe acute lung disease in infants is well established, but its mechanism is unclear. Most hypotheses assume that breastfeeding confers similar passive protection to every infant; however, a few observations have suggested that the benefits of breast milk against severe lung disease may differ according to gender. The objective of this study was to determine whether the effect of breastfeeding on susceptibility to severe acute lung disease among infants at high risk is different for girls and boys.

METHODS

A cohort was analyzed prospectively by use of 2 different strategies: (1) predictors of first episode of rehospitalization by univariate and multivariate analyses using robust Poisson regression and (2) mean number of rehospitalizations between groups using multiple regression negative binomial models.

RESULTS

A total of 119 high-risk, very low birth weight infants were enrolled. Breast milk protected girls but not boys against severe acute lung disease. The interaction between breastfeeding and gender was clinically and statistically significant, even after adjustment for variables that can affect severity of acute lung disease. Disease was most severe in formula-fed girls (versus formula-fed boys).

CONCLUSIONS

Breastfeeding decreased the risk for severe acute lung disease in girls but not in boys. These findings suggest that breast milk protection is not universally conferred by passive transfer of humoral immunity (which should be gender indifferent), show that respiratory symptoms may be amenable to nonspecific modulation, and identify nonbreastfed preterm infant girls as an at-risk group for severe acute lung disease.

Prospective study of breast-feeding in relation to wheeze, atopy, and bronchial hyperresponsiveness in the Avon Longitudinal Study of Parents and Children (ALSPAC)

BACKGROUND

Breast-feeding clearly protects against early wheezing, but recent data suggest that it might increase later risk of atopic disease and asthma.

OBJECTIVE

We sought to examine the relationship between breast-feeding and later asthma and allergy outcomes by using data from the Avon Longitudinal Study of Parents and Children, a large birth cohort in the United Kingdom.

METHODS

We used adjusted logistic regression models to evaluate the association between breast-feeding and atopy at age 7 years, bronchial responsiveness to methacholine at age 8 years, and wheeze at ages 3 and 7 1/2 years. Bayesian methods were used to assess the possibility of bias caused by an influence of early wheezing on the duration of breast-feeding, as well as selection bias.

RESULTS

Breast-feeding was protective for wheeze in the first 3 years of life (odds ratio [OR] of 0.80 [95% CI, 0.70-0.90] for > or = 6 months relative to never) but not wheeze (OR, 0.98; 95% CI, 0.79-1.22), atopy (OR, 1.12; 95% CI, 0.92-1.35), or bronchial hyperresponsiveness (OR, 1.07; 95% CI, 0.82-1.40) at ages 7 to 8 years. Bayesian models adjusting for the longer duration of breast-feeding among children with wheezing in early infancy produced virtually identical results.

CONCLUSIONS

We did not find consistent evidence for either a deleterious effect or a protective effect of breast-feeding on later risk of allergic disease in a large prospective birth cohort of children with objective outcome measures and extensive data on potential confounders and effect modifiers. Neither reverse causation nor loss to follow-up appears to have materially biased our results.

On the role of breastfeeding in health promotion and the prevention of allergic diseases

Based on animal models, we specify the major role of different bioactive milk components known to participate significantly in neonatal health promotion and in protection against a large number of infectious diseases and the development of allergies and asthma.

Effects of early nutritional interventions on the development of atopic disease in infants and children: the role of maternal dietary restriction, breastfeeding, timing of introduction of complementary foods, and hydrolyzed formulas

This clinical report reviews the nutritional options during pregnancy, lactation, and the first year of life that may affect the development of atopic disease (atopic dermatitis, asthma, food allergy) in early life. It replaces an earlier policy statement from the American Academy of Pediatrics that addressed the use of hypoallergenic infant formulas and included provisional recommendations for dietary management for the prevention of atopic disease. The documented benefits of nutritional intervention that may prevent or delay the onset of atopic disease are largely limited to infants at high risk of developing allergy (ie, infants with at least 1 first-degree relative [parent or sibling] with allergic disease). Current evidence does not support a major role for maternal dietary restrictions during pregnancy or lactation. There is evidence that breastfeeding for at least 4 months, compared with feeding formula made with intact cow milk protein, prevents or delays the occurrence of atopic dermatitis, cow milk allergy, and wheezing in early childhood. In studies of infants at high risk of atopy and who are not exclusively breastfed for 4 to 6 months, there is modest evidence that the onset of atopic disease may be delayed or prevented by the use of hydrolyzed formulas compared with formula made with intact cow milk protein, particularly for atopic dermatitis. Comparative studies of the various hydrolyzed formulas also indicate that not all formulas have the same protective benefit. There is also little evidence that delaying the timing of the introduction of complementary foods beyond 4 to 6 months of age prevents the occurrence of atopic disease. At present, there are insufficient data to document a protective effect of any dietary intervention beyond 4 to 6 months of age for the development of atopic disease.

Effect of prolonged and exclusive breast feeding on risk of allergy and asthma: cluster randomised trial

OBJECTIVE

To assess whether exclusive and prolonged breast feeding reduces the risk of childhood asthma and allergy by age 6.5 years.

DESIGN

Cluster randomised trial.

SETTING

31 Belarussian maternity hospitals and their affiliated polyclinics.

PARTICIPANTS

A total of 17,046 mother-infant pairs were enrolled, of whom 13,889 (81.5%) were followed up at age 6.5 years.

INTERVENTION

Breastfeeding promotion intervention modelled on the WHO/UNICEF baby friendly hospital initiative.

MAIN OUTCOME MEASURES

International study of asthma and allergies in childhood (ISAAC) questionnaire and skin prick tests of five inhalant antigens.

RESULTS

The experimental intervention led to a large increase in exclusive breast feeding at 3 months (44.3% v 6.4%; P<0.001) and a significantly higher prevalence of any breast feeding at all ages up to and including 12 months. The experimental group had no reduction in risks of allergic symptoms and diagnoses or positive skin prick tests. In fact, after exclusion of six sites (three experimental and three control) with suspiciously high rates of positive skin prick tests, risks were significantly increased in the experimental group for four of the five antigens.

CONCLUSIONS

These results do not support a protective effect of prolonged and exclusive breast feeding on asthma or allergy.

TRIAL REGISTRATION

Current Controlled Trials ISRCTN37687716 [controlled-trials.com].

WITHDRAWN: Cow's milk protein avoidance and development of childhood wheeze in children with a family history of atopy

BACKGROUND

In infants with a family history of atopy, food allergen avoidance has been advocated as means of preventing the development of atopic disease, when breast-feeding is not possible or supplemental feeding is needed. Most infant formulas are based on cow's milk protein. Alternative choices include soya based and hydrolysed cows milk formulas.

OBJECTIVES

To estimate the effect of dietary avoidance of cow's milk protein on the development of asthma or wheeze in children.

SEARCH STRATEGY

We searched the Cochrane database for eligible trials until February 2002. We obtained the full text papers of all abstracts identified as RCTs and two reviewers independently reviewed them.

SELECTION CRITERIA

We included randomised controlled trials involving children with a family history of atopy in at least one first degree relative, if feeding with cow's milk based standard formula was compared to dietary avoidance of cow's milk protein, using soya or other hypoallergenic formula during the initial four months of life or longer.

DATA COLLECTION AND ANALYSIS

Two reviewers extracted data independently. A priori defined subgroups were the types of hypoallergenic artificial feed and dietary restrictions on mother and/or child's diet.

MAIN RESULTS

Six trials used hydrolysed formula for at least four months, in addition to dietary restrictions and in some cases dust-mite reduction measures. The risk of infants experiencing asthma or wheeze during the first year of life was reduced compared to standard cow's milk based formula (Relative Risk 0.40, 95% Confidence Intervals 0.19 to 0.85). Feeding soya-based formula as opposed to standard cow's milk formula did not reduce the risk of having asthma or wheeze at any age.

AUTHORS' CONCLUSIONS

Breast-milk should remain the feed of choice for all babies. In infants with at least one first degree relative with atopy, hydrolysed formula for a minimum of four months combined with dietary restrictions and environment measures may reduce the risk of developing asthma or wheeze in the first year of life. There is insufficient evidence to suggest that soya-based milk formula has any benefit.

Severity of childhood asthma and human leukocyte antigens type

We sought to learn if Class II HLA genes are associated with the severity of asthma in children. We examined a previously recruited cohort of 340 healthy children who had Class II HLA allele data available. We conducted a comprehensive review of their medical records to determine asthma status and, when present, its severity. We found that Class II HLA alleles, which were previously reported to have an association with asthma incidence, appear to have an association as well with asthma severity. These data support our hypothesis that both the incidence and severity of asthma are heritable and that HLA may play an important role in both development and severity of asthma. Because of limited statistical power, our study findings are subject to further investigation.

Evolution of infant nutrition

Homo sapiens has developed during the course of over two million years. The social and physical conditions of life, the availability of milk and infant foods as well as the presence of diseases have all undergone radical transformations from the Stone Age, at first without and then with fire, to the hunter–gatherer, farmer–herder, agricultural and, now, developed societies. These changes in the human environment may have induced modifications in the length of pregnancy, the development of the neonate at birth, the duration of lactation, the composition of breast milk and use of weaning foods and milk substitutes. Darwinian selection for the nutrient, anti-infective and other components of breast milk may have been determined by the effects of nutrition, through genetic variations in milk composition, on the survival of infants and perhaps also on fecundity and disease resistance in later adult life. Today Darwinian selection may no longer be effective in maintaining or modifying human mammary function, because modern hygienic environments, together with the availability of nutritionally adequate breast-milk substitutes, permit infant survival even under conditions of total lactational failure. National and international promulgations strictly control the composition of infant formulas offered as breast-milk substitutes or as weaning foods. These recommendations are modified as beliefs suggest, and research indicates, the effects of nutrients and other factors on the health and well-being of the child. Preliminary observations on child health have often proved valuable in furthering research. Unquestioning acceptance of apparently desirable, but untested, epidemiological associations have led to unexpected but dangerous iatrogenic problems. Recommendations for change cannot safely be made without proper comparisons with present products and procedures under practical conditions. Such tests are time consuming and require protocols of appropriate statistical design and power while still meeting the required sociological and ethical constraints, but are essential to identify possible harmful effects of any proposed change. It is suggested that no novel ingredients should be added, or major changes permitted in any component, until appropriate trials have established the value and safety of the proposed modifications. Breast-feeding is vital to maximize infant survival in developing countries. There are major difficulties in assessing any differences in morbidity and mortality of breast-fed v. artificially reared infants in the developed world. Carefully controlled studies with comparisons of health and well-being, not only in infancy but throughout life, are desirable if the effects of infant nutrition on adult well-being, suggested by epidemiological studies, are to be validated and ultimately applied. There are considerable variations in the composition of breast milk. This variance suggests that it may ultimately be possible to design formulas better able to meet the needs of individual infants than the milk available from the mother's breast.

Breastfeeding and infant eczema in the first year of life in the KOALA birth cohort study: a risk period-specific analysis

OBJECTIVE

We studied the association between breastfeeding and eczema, taking into account the possible influence of reverse causation, with risk period-specific analyses.

METHODS

Information on breastfeeding, determinants, and outcomes at 1 year of age was collected with repeated questionnaires for 2405 mother-infant pairs participating in the KOALA (Child, Parent and Health: Lifestyle and Genetic Constitution [in Dutch]) birth cohort study. By using multivariate logistic regression analysis, we compared an overall analysis with risk period-specific analyses.

RESULTS

By the age of 1 year, 535 infants (22.2%) had developed eczema. In an overall analysis, we found a weak nonsignificant trend toward a reduced risk of eczema in the first year of life with increasing duration of breastfeeding (lowest risk for those breastfed for > or = 7 months versus never breastfed). In the risk period-specific analysis (confined to infants "at risk" for eczema onset after 3 months of age), no indication for reverse causation was found (results were not very different, compared with the overall analysis). Infants who were breastfed from birth on had a slightly (although not statistically significantly) increased risk for eczema in the first 3 months of life, compared with infants who were formula fed from birth on.

CONCLUSIONS

Our results indicated that no strong effect of breastfeeding on eczema in the first year of life was present. This conclusion was strengthened by risk period-specific analysis, which made the influence of reverse causation unlikely.

Breastfeeding history and childhood allergic status in a prospective birth cohort

BACKGROUND

Breastfeeding provides the best possible nutrition for newborns, but its role in the development of allergies is complex.

OBJECTIVE

To examine the relationship between breastfeeding and early childhood skin sensitization.

METHODS

In a birth cohort of 405 children from the Childhood Allergy Study, we used maternal report to classify children's duration of breastfeeding and whether they were breastfed only, formula fed only, or both. We examined the relationships between this information and childhood allergies as determined by skin prick testing for inhalant allergens at age 6 to 7 years.

RESULTS

There was no association between duration of breastfeeding and risk of allergic sensitization. Overall, children who were breastfed only were 50% more likely to have allergic sensitization than those fed formula only (relative risk [RR], 1.5; 95% confidence interval [CI], 1.1-2.1). Although the estimates are imprecise, this RR was higher for children born to mothers reporting a history of allergy (RR, 1.8; 95% CI, 1.0-3.0) than for those born to mothers with no allergic history (RR, 1.3; 95% CI, 0.9-2.1), for children in households without (RR, 1.6; 95% CI, 1.1-2.2) vs with (RR, 1.0; 95% CI, 0.3-4.0) multiple pets, and for those with an older sibling (RR, 2.0; 95% CI, 1.2-3.3) vs firstborns (RR, 1.3; 95% CI, 0.8-2.1).

CONCLUSIONS

Breastfeeding without formula supplementation may be associated with an increased risk of childhood allergies. However, this association may vary with birth order, exposure to household pets, and maternal allergic history.

Prolonged exclusive breastfeeding is associated with increased atopic dermatitis: a prospective follow-up study of unselected healthy newborns from birth to age 20 years

BACKGROUND

Exclusive breastfeeding for the first 6 months is recommended by the World Health Organization and considered allergy preventive. However, it is not known whether prolonging exclusive breastfeeding for over 6 months provides further benefit in allergy prevention.

OBJECTIVE

The aim of this prospective 20-year follow-up study was to find out whether the allergy protective effect can be enhanced by prolonging strictly exclusive breastfeeding for > or =9 months of age. A total of 200 unselected healthy newborns were enrolled in the study. Their mothers were encouraged to maintain exclusive breastfeeding for as long as possible. The number of infants on strictly exclusive breastfeeding was 167 at 2, 116 at 6, 36 at 9 and 7 at 12 months of age. Of the 200 infants, 42% had a family history of allergy. The children were re-assessed at ages 5 (n=163), 11 (n=150) and 20 years (n=164) with clinical examination, skin prick testing, and parental and personal structured interviews.

RESULTS

Exclusive breastfeeding prolonged for > or =9 months was associated with atopic dermatitis (P=0.002) and symptoms of food hypersensitivity (P=0.02) at age 5 years, and with symptoms of food hypersensitivity at age 11 years (P=0.01), in children with a family history of allergy.

CONCLUSION

Prolonging strictly exclusive breastfeeding for > or =9 months was not helpful in atopy prevention, instead, it was associated with increased atopic dermatitis and food hypersensitivity symptoms in childhood.

Breastfeeding does not increase the risk of asthma at 14 years

OBJECTIVES

There are conflicting data regarding the impact of breastfeeding on the development of asthma in late childhood. Our aim with this study was to investigate the relationship between breastfeeding and the prevalence of asthma in children at 14 years.

METHODS

The Mater-University of Queensland Study of Pregnancy is a birth cohort of 7223 women and their infants recruited from a public antenatal clinic in Brisbane, Australia, between 1981 and 1984. Data regarding breastfeeding and the duration of breastfeeding were collected through the use of a questionnaire completed by the mother 6 months postdelivery, and the prevalence of asthma was determined through the use of a questionnaire completed by the mother 14 years postdelivery.

RESULTS

Data regarding both breastfeeding and asthma were available for 4964 children. The prevalence of asthma in children at 14 years was 28.4%. Breastfeeding for > or =4 months was not found to have a significant effect on the prevalence of asthma in 14-year-olds. The unadjusted odds ratio of developing asthma at 14 years if the child was breastfed for > or =4 months was 1.03. The odds ratio of developing asthma did not change appreciably when allowance was made for potential confounding factors.

CONCLUSION

Data from this study indicate that breastfeeding neither increases nor decreases the prevalence of asthma in children at 14 years.

Atopic dermatitis prevention

A shift in focus from disease therapy toward disease prevention is occurring in many medical specialties, including dermatology. There are no generally accepted strategies for the prevention of atopic dermatitis. Most research has focused on allergen avoidance and has not produced consistently effective interventions. Immune cell modulation and skin barrier protection are examples of new approaches that hold promise for preventing, or modifying the course of, this common disease.