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

Abstract

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.

Keywords: asthma; breast milk; breastfeeding; developmental origins of health and disease; developmental programming; human milk; infant nutrition; wheezing.

Figure 1

Breastfeeding and the developmental origins of lung health and childhood asthma. Breastfeeding may be associated with lung heath through several potential mechanisms, including modulation of gut microbiota, epigenetics, immunity, and lung development. These processes are driven by multiple bioactive components of human milk, which are influenced by various fixed and modifiable maternal and infant factors. Understanding these mechanisms and associations will help to inform interventions to improve lung health and reduce asthma risk by supporting breastfeeding and optimizing milk composition and infant nutrition. SES, socioeconomic status.