The impact of breastfeeding on lung development and function: a systematic review

Breastfeeding and Lung Function of Children: A Systematic Review and Meta-Analysis

AIM

To evaluate the associations between breastfeeding and lung function among children without known respiratory diseases and to determine the effects of breastfeeding on spirometry.

METHODS

A systematic search of PubMed, Embase and Cochrane was performed from their inception to 11 Oct 2023 (PROSPERO identifier: CRD42023471664). Observational studies (cohort or cross-sectional or case-control design) and randomised controlled trials (RCTs) were searched. A random-effects model meta-analysis was used to estimate the effect size if significant heterogeneity was detected (p < 0.05 or I2 > 50%); Otherwise, the fixed-effects model was applied.

RESULTS

In total, 13 observational studies with 18 152 children were included in the qualitative synthesis, and five studies with 5305 children were included in the meta-analysis. Compared to children who were never breastfed, those who were breastfed had better FEV1 (β: 19.34 mL; 95% CI: 6.05, 32.64; p = 0.004) and PEF (β: 87.50 mL/s; 95% CI: 27.43, 147.58; p = 0.004). A similar trend was observed for FVC (β: 17.45 mL; 95% CI: -0.43, 35.33; p = 0.06). Furthermore, compared to children breastfed for less than three to four months, those breastfed for three to four months or more had better FEV1 (β: 19.86 mL; 95% CI: 4.21, 35.51; p = 0.01), FVC (β: 31.90 mL; 95% CI: 7.87, 55.93; p = 0.009) and PEF (β: 75.68 mL/s; 95% CI: 24.40, 126.97; p = 0.004).

CONCLUSION

This systematic review and meta-analysis revealed associations between breastfeeding and improved lung function in children aged 6-16 years. Further high-quality evidence is needed.

The Early Appearance of Asthma and Its Relationship with Gut Microbiota: A Narrative Review

Asthma is, worldwide, the most frequent non-communicable disease affecting both children and adults, with high morbidity and relatively low mortality, compared to other chronic diseases. In recent decades, the prevalence of asthma has increased in the pediatric population, and, in general, the risk of developing asthma and asthma-like symptoms is higher in children during the first years of life. The "gut-lung axis" concept explains how the gut microbiota influences lung immune function, acting both directly, by stimulating the innate immune system, and indirectly, through the metabolites it generates. Thus, the process of intestinal microbial colonization of the newborn is crucial for his/her future health, and the alterations that might generate dysbiosis during the first 100 days of life are most influential in promoting hypersensitivity diseases. That is why this period is termed the "critical window". This paper reviews the published evidence on the numerous factors that can act by modifying the profile of the intestinal microbiota of the infant, thereby promoting or inhibiting the risk of asthma later in life. The following factors are specifically addressed in depth here: diet during pregnancy, maternal adherence to a Mediterranean diet, mode of delivery, exposure to antibiotics, and type of infant feeding during the first three months of life.

Helicobacter pylori Infection Does Not Protect Against Allergic Diseases: Evidence From a Pediatric Cohort From Northern Sardinia, Italy

BACKGROUND

The "hygiene hypothesis" states that reduced exposure to microbial antigens due to an excessively hygienic environment can increase the risk of developing autoimmune diseases, including atopic disorders and asthma. In recent decades, there has been a progressive decline in the prevalence of numerous microorganisms following improved hygienic-sanitary conditions. More specifically, several studies reported an inverse association between the reduction in Helicobacter pylori infection and the rise of asthma and allergic disorders.

AIM

To evaluate the prevalence of atopic disorders in a pediatric population in relation to seropositivity against H. pylori.

METHODS

Children from Northern Sardinia, Italy, referred to the local Children's Hospital for any reason, were investigated to identify risk factors, especially H. pylori infection, associated with atopic disorders. A validated questionnaire, including demographics, house size, history of breastfeeding, residence, school or daycare center attendance, exposure to animals, and a defined diagnosis of atopy-including asthma-was filled out by a trained pediatrician according to parents' answers and child records. A blood sample was collected from each participant and immunoglobulin G against H. pylori was assessed by a locally validated ELISA test.

RESULTS

The seroprevalence of H. pylori infection was 11.7% among 492 children (240 females). Thirty-two children had a confirmed diagnosis of asthma and 12 of allergy. No one child showed both conditions. Statistically significant differences in H. pylori seropositivity were not detected between children with or without atopy (8.4% vs. 12.6; p = 0.233). Although atopic disorders were more frequent in children exposed to traditional atopic risk factors, none of them showed to be significant after adjusting for all covariates.

CONCLUSIONS

Serologically assessed H. pylori infection was not significantly associated with a reduced risk of atopic diseases in children.

Breastfeeding-Related Health Benefits in Children and Mothers: Vital Organs Perspective

Breast milk (BM) is a constantly changing fluid that represents the primary source of nutrition for newborns. It is widely recognized that breastfeeding provides benefits for both the child and the mother, including a lower risk of ovarian and breast cancer, type 2 diabetes mellitus, decreased blood pressure, and more. In infants, breastfeeding has been correlated with a lower risk of infectious diseases, obesity, lower blood pressure, and decreased incidence of respiratory infections, diabetes, and asthma. Various factors, such as the baby's sex, the health status of the mother and child, the mother's diet, and the mode of delivery, can affect the composition of breast milk. This review focuses on the biological impact of the nutrients in BM on the development and functionality of vital organs to promote the benefit of health.

P-Wave Axis of Schoolchildren Who Were Once Breastfed

BACKGROUND

It has been known for decades that breastfeeding leads to a lower risk of asthma, respiratory infections, or metabolic syndrome at school age. In addition, evidence is now accumulating on the influence of breast milk on the shape, volume, or function of the heart and lungs. Within this field of research into the effects of breast milk on the structure of the heart and lungs, we have set out to analyze the differential electrocardiographic characteristics of schoolchildren who were once breastfed.

METHOD

This was an observational cross-sectional study, including 138 children aged 6 or 12 consecutively presenting to a well-child clinic between May and December 2022.

INCLUSION CRITERIA

The ability to perform reproducible ECG records, the feasibility of weighing and measuring patient, and breastfeeding data collected from birth were used as the inclusion criteria.

RESULTS

Using the 40° cut-off value for the mean P-wave axis among schoolchildren, 76% of never-breastfed children in our sample have a P-wave axis in a more vertical position than the mean as compared to 58% of ever-breastfed children (OR: 2.25; 95% CI: 3.13-1.36); there was no other significant difference between infant feeding groups in somatometric characteristics or ECG parameters.

CONCLUSION

We found a significant difference of the mean values of the P-wave axis between never- and ever-breastfed children. Although this report should be approached cautiously, these findings add to the renewed interest in discerning developmental interventions to improve cardiovascular health.

Cardiometabolic effects of breastfeeding on infants of diabetic mothers

BACKGROUND

Breast milk is the best and principal nutritional source for neonates and infants. It may protect infants against many metabolic diseases, predominantly obesity and type 2 diabetes. Diabetes mellitus (DM) is a chronic metabolic and microvascular disease that affects all the body systems and all ages from intrauterine life to late adulthood. Breastfeeding protects against infant mortality and diseases, such as necrotizing enterocolitis, diarrhoea, respiratory infections, viral and bacterial infection, eczema, allergic rhinitis, asthma, food allergies, malocclusion, dental caries, Crohn's disease, and ulcerative colitis. It also protects against obesity and insulin resistance and increases intelligence and mental development. Gestational diabetes has short and long-term impacts on infants of diabetic mothers (IDM). Breast milk composition changes in mothers with gestational diabetes.

AIM

To investigate the beneficial or detrimental effects of breastfeeding on the cardiometabolic health of IDM and their mothers.

METHODS

We performed a database search on different engines and a thorough literature review and included 121 research published in English between January 2000 and December 15, 2022, in this review.

RESULTS

Most of the literature agreed on the beneficial effects of breast milk for both the mother and the infant in the short and long terms. Breastfeeding protects mothers with gestational diabetes against obesity and type 2 DM. Despite some evidence of the protective effects of breastfeeding on IDM in the short and long term, the evidence is not strong enough due to the presence of many confounding factors and a lack of sufficient studies.

CONCLUSION

We need more comprehensive research to prove these effects. Despite many obstacles that may enface mothers with gestational diabetes to start and maintain breastfeeding, every effort should be made to encourage them to breastfeed.

Association between History of Prolonged Exclusive Breast-Feeding and the Lung Function Indices in Childhood

Although the propitious effects of breastfeeding on children's health are indisputable, the impact of exclusive breastfeeding on the lung function later in life remains controversial. Our objective was to explore the possible associations between breastfeeding and the lung function of children who were exclusively breastfed for an extensive period of time. This was a cross-sectional study of children who were exclusively breastfed for more than 12 months. Demographics and anthropometric data were collected; the body mass index (BMI), % body fat, and % central obesity were calculated; and all the participants underwent standard spirometry with reversibility testing. The relationship between breastfeeding duration and spirometric parameters was assessed by Spearman's correlation and multivariable regression, after adjustment for other confounders. Forty-six children (21 boys), aged 9.2 ± 2.4 years, with a reported breastfeeding duration of 27.5 ± 12.5 months (range 12-60 months) were included; 13% were overweight (none were obese) and 21.7% had central obesity. The average FEV1 was 104.7 ± 10.4% and the average FEF25-75 was 107.9 ± 13.3%. The duration of exclusive breastfeeding was positively correlated with FEF25-75% (r = 0.422, p = 0.003). Multivariable linear regression analysis confirmed the above finding (beta coefficient 0.478, p = 0.002), independently of age, overweight, and central obesity. No correlation was noted between the duration of breastfeeding and other spirometric parameters. In addition to its favorable impact on the metabolic profile, prolonged exclusive breastfeeding seems to exert a propitious effect on the function of smaller airways throughout childhood.

The Role of Breastfeeding on Respiratory Outcomes Later in Childhood

BACKGROUND

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSION

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

Association of breastfeeding with tidal breathing analysis in infants with bronchiolitis

BACKGROUND

Tidal breathing flow-volume (TBFV) analysis provides important information about lung mechanics in infants.

AIM

To assess the effects of breastfeeding on the TBFV measurements of infants who recover from acute bronchiolitis.

METHODS

In this cross-sectional study, TBFV analysis was performed in infants with bronchiolitis prior to hospital discharge. The ratio of time to peak expiratory flow to total expiratory time (tPEF/tE) at baseline and after the administration of 400 mcg salbutamol was evaluated.

RESULTS

A total of 56 infants (35 boys), aged 7.4 ± 2.8 mo, were included. Of them, 12.5% were exposed to tobacco smoke and 41.1% were breastfed less than 2 mo. There were no differences in baseline TBFV measurements between the breastfeeding groups; however, those who breastfed longer than 2 mo had a greater change in tPEF/tE after bronchodilation (12% ± 10.4% vs 0.9% ± 7.1%; P < 0.001). Moreover, there was a clear dose-response relationship between tPEF/tE reversibility and duration of breastfeeding (P < 0.001). In multivariate regression analysis, infants who breastfed less (regression coefficient -0.335, P = 0.010) or were exposed to cigarette smoke (regression coefficient 0.353, P = 0.007) showed a greater change in tPEF/tE after bronchodilation, independent of sex, prematurity, and family history of asthma or atopy.

CONCLUSION

Infants who recover from bronchiolitis and have a shorter duration of breastfeeding or are exposed to cigarette smoke, have TBFV measurements indicative of obstructive lung disease.

Influence of Nutrition and Maternal Bonding on Postnatal Lung Development in the Newborn Pig

Background

Microbial colonization and immune cell maturation coincide at mucosal sites and are decisive for postnatal lung development. How external factors influence neonatal pulmonary immune development is poorly understood.

Objective

To elucidate the impact of key determinants in early life, nutrition, and maternal bonding, on postnatal lung maturation in a human-relevant animal model. To investigate the underlying immunological changes of impaired lung maturation and study the mechanisms of conversion.

Methods

Newborn piglets were kept with or without isolation from their mothers and fed bovine milk-based infant formula or received milk of sow. Lung growth, histomorphology, respiratory immune responses, and lung microbiota were analyzed. Mother- and sow-milk-deprived piglets received maternal material or were reintroduced to the maternal environment at varying intervals to study options for reversal.

Results

Formula feeding combined with isolation of newborn piglets resulted in disturbed postnatal lung maturation. Reduced lung growth correlated with dampened IL-33 expression, impaired lung myeloid cell activation, and decreased Th1 differentiation, along with diminished richness and diversity of the lung microbiota. Transfer of bacteria-enriched maternal material reversed the negative effects on pulmonary immune maturation. Early (within 3 days) but not late (within 7 days) reintroduction to the mother allowed restoration of normal lung development.

Conclusion

Our findings reveal that lung growth, respiratory immunity, and microbial lung colonization in newborns depend on postnatal diet and maternal contact, and targeting these key regulators could promote lung development during this critical life stage.

Summary

Disturbances in natural diet and reduced maternal contact during the neonatal period impair postnatal lung maturation. In pediatrics, timely breast milk feeding and intensive maternal bonding represent valuable intervention measures to promote early postnatal lung development.

Changes in children's lung function over two decades in relation to socioeconomic, parental and household factors in Wuhan, China

Background

It is important to identify risk and beneficial factors for children's lung function. This study aims to ascertain potential changes in children's lung function in relation to changes in socioeconomic, parental and household factors, based on a comparison between two periods spanning 25 years in Wuhan, the largest metropolis in central China.

Methods

In two cross-sectional studies, lung function measurements and questionnaire surveys were conducted on school-age children in 1993-1996 (Period I) and in 2018 (Period II). Children of 6-12 years old from elementary schools were selected by a multistage sampling method. Demographic information, socioeconomic status, feeding methods, parental illness and behavior patterns, as well as household characteristics, were collected through a questionnaire survey. Spirometric lung function was measured, including forced vital capacity (FVC), forced expiratory volume in the first second (FEV₁), forced expiratory flow at 25% and 75% of the pulmonary volume (FEF25-75), and peak expiratory flow (PEF). Wilcoxon analysis of variances was used to assess the differences in lung function indexes between Period I and Period II. Multiple linear regression models were used to estimate the association of lung function with regard to socioeconomic, parental and household factors, respectively.

Results

Significant prevalence reductions were observed for household coal use, paternal smoking and maternal asthma, while the prevalence increased significantly for children sleeping in their own rooms or own beds and breastfeeding, ventilation use during cooking, and parental education level from Period I to Period II. When adjusted for age, height, weight, sex and other factors assessed in the study, children had significant lower values of FVC, FEV₁, and PEF in Period II than in Period I. Enclosed kitchen was significantly associated with lower lung function in children in Period I. Urban living condition and higher maternal education level were each associated with a higher FVC, while father having no fixed income was associated with a lower FVC and a lower FEV₁, respectively, in Period II. In comparison with Period I, the beneficial impact of urban living and that of breastfeeding were enhanced and the detrimental effect of poor household condition was weakened in Period II.

Conclusions

Lung function was lower in 2018 than in 1993-1996 in school-age children living in Wuhan. Although improvements in urban living and household environmental conditions as well as increased breastfeeding in Period II could have contributed to increased lung function, other unmeasured risk factors may have played a more dominant role in leading to a net decrease in lung function from Period I to Period II. Future studies are needed to identify these risk factors.

Childhood Origins of Adult Lung Disease as Opportunities for Prevention

Prenatal and childhood exposures have been shown to impact lung development, lung function trajectory, and incidence and prevalence of respiratory disease. Early life may serve as a window of susceptibility to such exposures, with the potential to influence lifelong respiratory health. Risk factors encountered in early life with potentially durable impact on lung health include prematurity, respiratory viral illness, allergen sensitization and exposure, tobacco use and exposure, indoor and outdoor pollution, diet, and obesity. These exposures vary in the extent to which they are modifiable, and interventions aimed at reducing harmful exposures range from individual-level behavior modification to policy initiatives implemented to promote population health. For many exposures, including tobacco-related exposures, multilevel interventions are needed. Future research is needed to provide insight as to early-life interventions to promote optimal lung growth and prevent development of chronic respiratory disease. Clinicians should play an active role, assisting individual patients in avoiding known detrimental exposures including maternal smoking during pregnancy and initiation of active smoking. Clinicians can be empowered by evidence to support policies promoting reduction of population-level risk factors, such as restriction on electronic cigarette sales and legislation to uphold air quality standards, to encourage attainment of maximal lung function and reduce risk of chronic lung disease.

Air pollution during infancy and lung function development into adolescence: The GINIplus/LISA birth cohorts study

BACKGROUND

Limited evidence exists on how air pollution exposure during infancy, i.e. the first year of life, may affect lung function development into adolescence.

OBJECTIVES

To investigate the association between exposure to air pollution during the first-year of life and lung function development up to the age of 15 in Germany.

METHODS

We investigated 915 children from the GINIplus and LISA birth cohorts from Munich (n = 181) and Wesel (n = 734), who had at least two spirometric measurements at ages 6, 10 and 15. Z-scores of forced expiratory volume in one second (FEV₁) and forced vital capacity (FVC) were calculated. Annual average concentrations of nitrogen dioxide, particulate matter with diameters <2.5, <10 and 2.5-10 µm (PM_{2.5/10/coarse}), and PM_2.5 absorbance at home addresses during the first-year of life, were estimated by land-use regression models. Associations between infancy exposure and lung function changes were fitted using multivariable linear mixed models with adjustment for potential confounders.

RESULTS

For per interquartile range increase in air pollutants during the first-year life, FEV₁ z-scores declined annually by -0.012 (95% confidence interval (CI): -0.014, -0.009) for PM_2.5 to -0.023 (95%CI: -0.028, -0.018) for PM_coarse. The declines in FVC were lower than FEV₁ [-0.006 (95%CI: -0.008, -0.003) to -0.011 (95%CI: -0.019, -0.003)]. In Munich, the attenuations were only significant for FEV₁. Effect estimates of infancy exposure for certain air pollutants were higher for groups with asthma, older maternal age, and breastfeeding <12 weeks than their counterparts.

DISCUSSION

Infancy exposure to higher air pollution may reduce lung function development up to adolescence, with airway size more affected than lung volume restriction. The potential modifying effects of maternal age, asthmatic status of children and breastfeeding warrant further exploration.

Amniotic fluid and breast milk: a rationale for breast milk stem cell therapy in neonatal diseases

Amniotic fluid and breast milk play important roles in structural development throughout fetal growth and infancy. Given their significance in physical maturation, many studies have investigated the therapeutic and protective roles of amniotic fluid and breast milk in neonatal diseases. Of particular interest to researchers are stem cells found in the two fluids. These stem cells have been investigated due to their ability to self-replicate, differentiate, reduce tissue damage, and their expression of pluripotent markers. While amniotic fluid stem cells have received some attention regarding their ability to treat neonatal diseases, breast milk stem cells have not been investigated to the same extent given the recency of their discovery. The purpose of this review is to compare the functions of amniotic fluid, breast milk, and their stem cells to provide a rationale for the use of breast milk stem cells as a therapy for neonatal diseases. Breast milk stem cells present as an important tool for treating neonatal diseases given their ability to reduce inflammation and tissue damage, as well as their multilineage differentiation potential, easy accessibility, and ability to be used in disease modelling.

Maternal asthma, breastfeeding, and respiratory outcomes in the first year of life

Maternal asthma increases the risk of infant wheeze. Breastfeeding may offer protection but there is limited evidence in this high-risk group. We examined associations between breastfeeding and respiratory outcomes, in infants born to women with asthma. This study was a secondary analysis of two prospective cohorts of pregnant women with asthma, and their infants, conducted between 2007 and 2018. At 6 ± 1 (T1) and 12 ± 1 (T2) months post-partum, mothers reported breastfeeding patterns and infant wheeze (primary outcome), bronchiolitis, and related medication use and healthcare utilization, via a validated questionnaire; a subgroup completed face-to-face interviews. χ² tests and logistic regression models, adjusting for confounders, were utilized. Data were complete for 605 participants at T1 and 486 (80%) at T2. Of 605 participants: 89% initiated breastfeeding and 38% breastfed for more than 6 months. Breastfeeding for more than 6 months vs "never" was associated with a reduced adjusted relative risk of infant wheeze at T1 (0.54, 95% confidence interval, 0.30-0.96). Bronchiolitis risk was reduced at T1 and T2 with more tha 6 months of breastfeeding vs "never." Breastfeeding duration of 1 to 3 months, 4 to 6 months, and more than 6 months were associated with a reduced risk of infant healthcare utilization (all P < .05, vs "never"), but not medication use (P > .05). Breastfeeding for more than 6 months was associated with a reduced risk of wheeze, bronchiolitis, and wheeze-related healthcare utilization in infants at risk due to maternal asthma. Notably, breastfeeding for shorter durations was associated with a reduced risk of healthcare utilization compared with none. Larger cohorts are needed to further examine the impact of breastfeeding exposure on respiratory health in infants exposed to maternal asthma.

Effect of breastfeeding duration on lung function, respiratory symptoms and allergic diseases in school-age children

BACKGROUND

A positive effect of breastfeeding on lung function has been demonstrated in cohorts of children with asthma or risk for asthma. We assessed the impact of breastfeeding on lung function and symptoms at the age of 6 years in an unselected, healthy birth cohort.

METHODS

We prospectively studied healthy term infants from the Bern-Basel Infant Lung Development (BILD) cohort from birth up to 6 years. Any breastfeeding was assessed by weekly phone calls during the first year of life. Risk factors (eg, smoking exposure, parental history of allergic conditions, and education) were obtained using standardized questionnaires. The primary outcomes were lung function parameters measured at 6 years of age by spirometry forced expiratory volume in 1 second, body plethysmography (functional residual capacity [FRCpleth ], the total lung capacity [TLCpleth ], and the effective respiratory airway resistance [Reff ]) and fractional exhaled nitric oxide (FeNO). Secondary outcomes included ever wheeze (between birth and 6 years), wheeze in the past 12 months, asthma, presence of allergic conditions, atopic dermatitis, rhinitis, and positive skin prick test at the age of 6 years.

RESULTS

In 377 children the mean breastfeeding duration was 36 weeks (SD 14.4). We found no association of breastfeeding duration with obstructive or restrictive lung function and FeNO. After adjustment for confounders, we found no associations of breastfeeding duration with respiratory symptoms or the presence of allergic conditions.

CONCLUSION

This study found no evidence of an association between breastfeeding and comprehensive lung function in unselected healthy children with long-term breastfeeding. Our findings do not support the hypothesis that the duration of breastfeeding has a direct impact on lung function in a healthy population with low asthmatic risk.

Lipid mediators and asthma: Scope of therapeutics

Lipids and their mediators are known to play a pro-inflammatory role in several human diseases including asthma. The influence of leukotrienes and prostaglandins through arachidonate metabolism in asthma pathophysiology is well established and hence, prompted the way for therapeutic strategies targeting lipid metabolites. In addition, various types of fatty acids have been reported to play a diverse role in asthma. For instance, CD4⁺ T-lymphocytes differentiation towards T-effector (T_eff) or T-regulatory (Tregs) cells seems to be controlled reciprocally by fatty acid metabolic pathways. Further, the dysregulated lipid status in obesity complicates the asthma manifestations suggesting the role of lipid metabolites particularly ω-6 fatty acids in the process. On the other hand, clinical and pre-clinical studies suggests the role of short chain fatty acids in curbing asthma through upregulation of T-regulatory cells or clearance of inflammatory cells through promoting apoptosis. Accordingly, the present review compiles various studies for comprehensive analysis of different types of lipid based metabolites in asthma manifestation. Finally, we have proposed certain strategies which may enhance the usefulness of lipid mediators for balanced immune response during asthma.

Protective Effect of Breastfeeding on the Adverse Health Effects Induced by Air Pollution: Current Evidence and Possible Mechanisms

Air pollution is a major social, economic, and health problem around the world. Children are particularly susceptible to the negative effects of air pollution due to their immaturity and excessive growth and development. The aims of this narrative review were to: (1) summarize evidence about the protective effects of breastfeeding on the adverse health effects of air pollution exposure, (2) define and describe the potential mechanisms underlying the protective effects of breastfeeding, and (3) examine the potential effects of air pollution on breastmilk composition and lactation. A literature search was conducted using electronic databases. Existing evidence suggests that breastfeeding has a protective effect on adverse outcomes of indoor and outdoor air pollution exposure in respiratory (infections, lung function, asthma symptoms) and immune (allergic, nervous and cardiovascular) systems, as well as under-five mortality in both developing and developed countries. However, some studies reported no protective effect of breastfeeding or even negative effects of breastfeeding for under-five mortality. Several possible mechanisms of the breastfeeding protective effect were proposed, including the beneficial influence of breastfeeding on immune, respiratory, and nervous systems, which are related to the immunomodulatory, anti-inflammatory, anti-oxidant, and neuroprotective properties of breastmilk. Breastmilk components responsible for its protective effect against air pollutants exposure may be long chain polyunsaturated fatty acids (LC PUFA), antioxidant vitamins, carotenoids, flavonoids, immunoglobins, and cytokines, some of which have concentrations that are diet-dependent. However, maternal exposure to air pollution is related to increased breastmilk concentrations of pollutants (e.g., Polycyclic aromatic hydrocarbons (PAHs) or heavy metals in particulate matter (PM)). Nonetheless, environmental studies have confirmed that breastmilk's protective effects outweigh its potential health risk to the infant. Mothers should be encouraged and supported to breastfeed their infants due to its unique health benefits, as well as its limited ecological footprint, which is associated with decreased waste production and the emission of pollutants.

Association of Breastfeeding and Air Pollution Exposure With Lung Function in Chinese Children

IMPORTANCE

Breastfeeding and exposure to ambient air pollutants have been found to be independently associated with respiratory health in children; however, previous studies have not examined the association of breastfeeding as a potential moderator of the association.

OBJECTIVE

To assess associations of breastfeeding and air pollution with lung function in children.

DESIGN, SETTING, AND PARTICIPANTS

Using a cross-sectional study design, children were recruited from 62 elementary and middle schools located in 7 Chinese cities from April 1, 2012, to October 31, 2013. Data analyses were conducted from November 1, 2018, to March 31, 2019.

EXPOSURES

Long-term concentrations of airborne particulate matter with a diameter of 1 μm or less (PM1), airborne particulate matter with a diameter of 2.5 μm or less (PM2.5), airborne particulate matter with a diameter of 10 μm or less (PM10), and nitrogen dioxide were estimated using a spatial statistical model matched to children's geocoded home addresses, and concentrations of PM10, sulfur dioxide, nitrogen dioxide, and ozone were measured by local air monitoring stations.

MAIN OUTCOMES AND MEASURES

Breastfeeding was defined as maternal report of having mainly breastfed for longer than 3 months. Lung function was measured using portable electronic spirometers. Using previously published predicted spirometric values for children in Northeast China as the reference, lung impairment was defined as forced vital capacity (FVC) less than 85%, forced expiratory volume in the first second of expiration less than 85%, peak expiratory flow less than 75%, or maximum midexpiratory flow less than 75%.

RESULTS

Participants included 6740 children (mean [SD] age, 11.6 [2.1] years; 3382 boys [50.2%]). There were 4751 children (70.5%) who were breastfed. Mean (SD) particulate matter concentrations ranged from 46.8 (6.5) μg/m3 for PM1 to 95.6 (9.8) μg/m3 for PM10. The prevalence of lung function impairment ranged from 6.8% for peak expiratory flow to 11.3% for FVC. After controlling for age, sex, and other covariates, 1-interquartile range greater concentration of pollutants was associated with higher adjusted odds ratios (AORs) for lung function impairment by FVC among children who were not breastfed compared with those who were (PM1: AOR, 2.71 [95% CI, 2.02-3.63] vs 1.20 [95% CI, 0.97-1.48]; PM2.5: AOR, 2.27 [95% CI, 1.79-2.88] vs 1.26 [95% CI, 1.04-1.51]; and PM10: AOR, 1.93 [95% CI, 1.58-2.37] vs 1.46 [95% CI, 1.23-1.73]). Younger age (<12 years) was associated with lower lung function impairment among the children who had been breastfed. In children from elementary schools, 1-interquartile range greater concentration of pollutants was associated with higher AORs for lung function impairment by FVC among children who had not been breastfed compared with those who had (PM1: AOR, 6.43 [95% CI, 3.97-10.44] vs 1.89 [95% CI, 1.28-2.80]; PM2.5: AOR, 3.83 [95% CI, 2.63-5.58] vs 1.50 [95% CI, 1.12-2.01]; and PM10: AOR, 2.61 [95% CI, 1.90-3.57] vs 1.52 [95% CI, 1.19-1.95]). Results from linear regression models also showed associations of air pollution with worse lung function among children who were not breastfed compared with their counterparts who were breastfed, especially for FVC (PM1: β, -240.46 [95% CI, -288.71 to -192.21] vs -38.21 [95% CI, -69.27 to -7.16] mL) and forced expiratory volume in the first second of expiration (PM1: β, -201.37 [95% CI, -242.08 to -160.65] vs -30.30 [95% CI, -57.66 to -2.94] mL).

CONCLUSIONS AND RELEVANCE

In this study, breastfeeding was associated with lower risk of lung function impairment among children in China exposed to air pollution, particularly among younger children.

Impact of breast milk on respiratory outcomes in infants with bronchopulmonary dysplasia

BACKGROUND

The objective of our study was to examine whether outpatient respiratory morbidities in infants with bronchopulmonary dysplasia (BPD) are influenced by the human milk consumption.

METHODS

Caregivers of subjects recruited from a BPD clinic completed questionnaires regarding breast milk intake and respiratory outcomes.

RESULTS

One-hundred eighty-eight caregivers completed the questionnaire. Of these, 173 (92.0%) reported that the child received some breast milk. Infants who received breast milk for fewer months were more likely to be non-white, and have a lower household income, public insurance, and secondhand smoke exposure. A longer receipt of breast milk was associated with reduced likelihoods of emergency department visits, systemic steroid courses, and cough or chest congestion, and a trend towards a lower risk of re-hospitalizations.

CONCLUSIONS

Longer duration of breast milk intake was associated with markers of higher socio-economic status, and reduced likelihood of acute and chronic respiratory morbidities among preterm infants with bronchopulmonary dysplasia.

Breastfeeding and the Developmental Origins of Asthma: Current Evidence, Possible Mechanisms, and Future Research Priorities

Breastfeeding has many established health benefits, but its impact on asthma development is uncertain. Breastfeeding appears to have a positive and dose-dependent impact on respiratory health, particularly during early childhood and in high-risk populations; however, the strength and causality of these associations are unclear. It is challenging to compare results across studies due to methodological differences and biological variation. Resolving these inconsistencies will require well-designed, prospective studies that accurately capture asthma diagnoses and infant feeding exposures (including breastfeeding duration, exclusivity, and method of feeding), account for key confounders, evaluate dose effects, and consider effect modification and reverse causality. Mechanistic studies examining human milk bioactives and their impact on lung health and asthma development are beginning to emerge, and these will be important in establishing the causality and mechanistic basis of the observed associations between breastfeeding and asthma. In this review, we summarize current evidence on this topic, identify possible reasons for disagreement across studies, discuss potential mechanisms for a causal association, and provide recommendations for future research.

Nutrition and Lung Growth

Experimental evidence from animal models and epidemiology studies has demonstrated that nutrition affects lung development and may have a lifelong impact on respiratory health. Chronic restriction of nutrients and/or oxygen during pregnancy causes structural changes in the airways and parenchyma that may result in abnormal lung function, which is tracked throughout life. Inadequate nutritional management in very premature infants hampers lung growth and may be a contributing factor in the pathogenesis of bronchopulmonary dysplasia. Recent evidence seems to indicate that infant and childhood malnutrition does not determine lung function impairment even in the presence of reduced lung size due to delayed body growth. This review will focus on the effects of malnutrition occurring at critical time periods such as pregnancy, early life, and childhood, on lung growth and long-term lung function.

Effect of an Intervention to Promote Breastfeeding on Asthma, Lung Function, and Atopic Eczema at Age 16 Years: Follow-up of the PROBIT Randomized Trial

IMPORTANCE

Atopic diseases, including asthma and atopic eczema, are the most common chronic conditions of childhood.

OBJECTIVE

To investigate whether an intervention to promote prolonged and exclusive breastfeeding protects against asthma, atopic eczema, and low lung function in adolescence.

DESIGN, SETTING, AND PARTICIPANTS

Follow-up of the Promotion of Breastfeeding Intervention Trial (PROBIT), a cluster randomized trial in 30 Belarusian maternity hospitals and affiliated polyclinics; recruitment of 17 046 healthy term infants took place from June 15, 1996, to December 31, 1997. Data analysis was conducted from May 9, 2016, to April 21, 2017. The primary analytic approach was by modified intention-to-treat analysis.

INTERVENTIONS

Randomization to receive a breastfeeding promotion intervention vs usual care.

MAIN OUTCOMES AND MEASURES

Spirometry and flexural eczema on standardized skin examination by study pediatricians were the primary outcomes; secondary outcomes were self-reported asthma diagnosis ever, and wheezing and flexural eczema symptoms in the previous year.

RESULTS

A total of 13 557 (79.5%) participants were followed up from September 15, 2012 to July 15, 2015. The intervention (7064 [79.7%]) and control (6493 [79.4%]) groups were similar at follow-up (3590 [50.8%] and 3391 [52.2%] male; mean [SD] age, 16.2 [0.6] and 16.1 [0.5] years, respectively). In the intervention group, 0.3% (21 of 7064) had flexural eczema on skin examination and mean (SD) forced expiratory volume in the first second of expiration/forced vital capacity (FEV1/FVC) ratio z score was -0.10 (1.82), compared with 0.7% (43 of 6493) and 0.35 (1.34), respectively, in the control group. In modified intention-to-treat analysis, accounting for clustering by polyclinic, a 54% lower risk of flexural eczema on skin examination was observed in the intervention compared with the control group (odds ratio [OR], 0.46; 95% CI, 0.25 to 0.86). Self-reported flexural eczema symptoms in the past year (OR, 0.57; 95% CI, 0.27 to 1.18), asthma (OR, 0.76; 95% CI, 0.47 to 1.23), and wheezing in the past year (OR, 0.66; 95% CI, 0.37 to 1.18) were less frequently reported in the intervention compared with the control group, but 95% CIs were wide and included the null. There was no significant difference in the FEV1/FVC ratio z score (β -0.15; 95% CI, -0.76 to 0.45). All results were similar with additional adjustment for baseline characteristics, on instrumental variable analysis, and with multiple imputation among all 17 046 randomized participants.

CONCLUSIONS AND RELEVANCE

A breastfeeding promotion intervention reduced flexural dermatitis risk but had no detectable effect on lung function or questionnaire-derived measures of atopic eczema or asthma in adolescence in a setting where atopic eczema and allergies are rare.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT01561612.

The Prebiotic and Probiotic Properties of Human Milk: Implications for Infant Immune Development and Pediatric Asthma

The incidence of pediatric asthma has increased substantially in recent decades, reaching a worldwide prevalence of 14%. This rapid increase may be attributed to the loss of "Old Friend" microbes from the human microbiota resulting in a less diverse and "dysbiotic" gut microbiota, which fails to optimally stimulate immune development during infancy. This hypothesis is supported by observations that the gut microbiota is different in infants who develop asthma later in life compared to those who remain healthy. Thus, early life exposures that influence gut microbiota play a crucial role in asthma development. Breastfeeding is one such exposure; it is generally considered protective against pediatric asthma, although conflicting results have been reported, potentially due to variations in milk composition between individuals and across populations. Human milk oligosaccharides (HMOs) and milk microbiota are two major milk components that influence the infant gut microbiota and hence, development of the immune system. Among their many immunomodulatory functions, HMOs exert a selective pressure within the infant gut microbial niche, preferentially promoting the proliferation of specific bacteria including Bifidobacteria. Milk is also a source of viable bacteria originating from the maternal gut and infant oral cavity. As such, breastmilk has prebiotic and probiotic properties that can modulate two of the main forces controlling the gut microbial community assembly, i.e., dispersal and selection. Here, we review the latest evidence, mechanisms and hypotheses for the synergistic and/or additive effects of milk microbiota and HMOs in protecting against pediatric asthma.

Diet and Asthma: Is It Time to Adapt Our Message?

Asthma is a chronic respiratory disorder which is associated with airway inflammation. Environmental factors, in association with genetic susceptibility, play a critical role in asthma pathophysiology. Inhaled allergens, smoke exposure, indoor and outdoor air pollution are common triggers of asthma symptoms. Although the role of diet has clearly established mechanisms in diseases such as cardiovascular disease, type 2 diabetes, and cancer, it is not commonly identified as a causal factor in asthma. However, some dietary patterns, such as the Western diet, which includes a high intake of refined grains, processed and red meats, and desserts, have pro-inflammatory effects. On the contrary, the Mediterranean diet, with high intake of fruits and vegetables has anti-inflammatory properties. The influence of food on asthma outcomes is of growing interest, but dietary habits of asthma patients are not commonly investigated in clinical practice. In this review, we focus on the impact of diet on asthma risk and asthma control. We also detail the influence of diet on obese patients with asthma.

Breastfeeding associated with higher lung function in African American youths with asthma

OBJECTIVE

In the United States, Puerto Ricans and African Americans have lower prevalence of breastfeeding and worse clinical outcomes for asthma compared with other racial/ethnic groups. We hypothesize that the history of breastfeeding is associated with increased forced expiratory volume in 1 second (FEV1) % predicted and reduced asthma exacerbations in Latino and African American youths with asthma.

METHODS

As part of the Genes-environments & Admixture in Latino Americans (GALA II) Study and the Study of African Americans, asthma, Genes & Environments (SAGE II), we conducted case-only analyses in children and adolescents aged 8-21 years with asthma from four different racial/ethnic groups: African Americans (n = 426), Mexican Americans (n = 424), mixed/other Latinos (n = 255), and Puerto Ricans (n = 629). We investigated the association between any breastfeeding in infancy and FEV1% predicted using multivariable linear regression; Poisson regression was used to determine the association between breastfeeding and asthma exacerbations.

RESULTS

Prevalence of breastfeeding was lower in African Americans (59.4%) and Puerto Ricans (54.9%) compared to Mexican Americans (76.2%) and mixed/other Latinos (66.9%; p < 0.001). After adjusting for covariates, breastfeeding was associated with a 3.58% point increase in FEV1% predicted (p = 0.01) and a 21% reduction in asthma exacerbations (p = 0.03) in African Americans only.

CONCLUSION

Breastfeeding was associated with higher FEV1% predicted in asthma and reduced number of asthma exacerbations in African American youths, calling attention to continued support for breastfeeding.

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Duration and exclusiveness of breastfeeding and school-age lung function and asthma

BACKGROUND

Breastfeeding reduces the risk of asthma in early childhood, but it is not clear whether its effect on respiratory morbidity is still present in later childhood.

OBJECTIVE

To examine the associations of any breastfeeding, breastfeeding duration, and breastfeeding exclusiveness with lung function and asthma in school-aged children and whether associations were influenced by respiratory tract infections and maternal or child's atopic status.

METHODS

This study of 4,464 children was embedded in a population-based prospective cohort study. Information on breastfeeding was obtained by multiple questionnaires from birth until 1 year of age. At 10 years of age, lung function was measured by spirometry, and information on asthma was obtained by questionnaire. Adjusted linear and logistic regression models were used to examine the associations.

RESULTS

Shorter duration of breastfeeding was associated with a lower forced expiratory volume in 1 second (FEV₁) only (z score change, -0.01; 95% confidence interval [CI], -0.02 to -0.00) per month shorter breastfeeding, but not asthma. When categorized, breastfeeding for 2 to 4 months was associated with a lower forced vital capacity (FVC) (z score change, -0.11; 95% CI, -0.20 to -0.03) compared with breastfeeding for 6 months or longer. Nonexclusive breastfeeding for 4 months was associated with a lower FVC (z score change, -0.08; 95% CI, -0.16 to -0.01) compared with exclusive breastfeeding for 4 months. Results did not materially change after additional adjustment for lower respiratory tract infections and were not modified by maternal history of asthma or atopy, child's eczema, or inhalant allergic sensitization.

CONCLUSION

Shorter duration and nonexclusivity of breastfeeding were associated with a lower FEV₁ and FVC but not asthma at school-age.

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.

Effects of Breastfeeding on Respiratory Symptoms in Infancy

OBJECTIVE

To assess the impact of potential risk factors on the development of respiratory symptoms and their specific modification by breastfeeding in infants in the first year of life.

STUDY DESIGN

We prospectively studied 436 healthy term infants from the Bern-Basel Infant Lung Development cohort. The breastfeeding status, and incidence and severity of respiratory symptoms (score) were assessed weekly by telephone interview during the first year of life. Risk factors (eg, pre- and postnatal smoking exposure, mode of delivery, gestational age, maternal atopy, and number of older siblings) were obtained using standardized questionnaires. Weekly measurements of particulate matter <10 μg were provided by local monitoring stations. The associations were investigated using generalized additive mixed model with quasi Poisson distribution.

RESULTS

Breastfeeding reduced the incidence and severity of the respiratory symptom score mainly in the first 27 weeks of life (risk ratio 0.70; 95% CI 0.55-0.88). We found a protective effect of breastfeeding in girls but not in boys. During the first 27 weeks of life, breastfeeding attenuated the effects of maternal smoking during pregnancy, gestational age, and cesarean delivery on respiratory symptoms. There was no evidence for an interaction between breastfeeding and maternal atopy, number of older siblings, child care attendance, or particulate matter <10 μg.

CONCLUSIONS

This study shows the risk-specific effect of breastfeeding on respiratory symptoms in early life using the comprehensive time-series approach.

The effect of breastfeeding on lung function at 12 and 18 years: a prospective cohort study

The objective was to assess associations between duration of total and exclusive breastfeeding and lung function up to adolescence.A birth cohort (Melbourne Atopy Cohort Study) of 620 infants with a family history of allergic disease was recruited. Mothers were encouraged to breastfeed exclusively for 6 months. Lung function was assessed at 12 and 18 years of age. Associations between breastfeeding and lung function were investigated using multivariable linear regression and path analysis was used to assess the potential mediating factors.Duration of breastfeeding (total and exclusive) was not associated with most assessed lung function outcomes. However, there was a trend for increased pre-bronchodilator mid-expiratory flow (MEF) at both 12 (adjusted mean difference (95% CI) per week of breastfeeding of 10 (-1-20) mL·s(-1)) and 18 years (11 (-1-22) mL·s(-1)) (p-values of 0.07 and 0.08, respectively). There was a strong indirect effect of height on these observed associations.Duration of breastfeeding does not appear to greatly influence lung function outcomes in children with a family history of allergic diseases. Longer duration of exclusive breastfeeding may be associated with an increase in MEF, partly due to greater attained height of the child.