Breast milk components modulate gut microbiota to increase susceptibility to atopic dermatitis in early life

The colonisation and assembly of the neonatal microbiota is essential for the development and maturation of the immune system, and the early life from birth to 2 years of age is regarded as a crucial window period. Abnormal microbial colonisation and reduced gut microbiota diversity during this period are linked to the subsequent development of immune-mediated diseases. Dysbiosis of intestinal microbiota in early life can promote dysfunction of the CD4+ T-cell population,1 impacting the development of the child’s immune system and increasing the risk of atopic diseases. Atopic diseases are excessive IgE-mediated immune responses that commonly affect the nose, eyes, skin and lungs. Of these, atopic dermatitis (AD), a chronic and recurring inflammatory skin disease, affects at least 10%–20% of children, often starting in infancy and continuing into adulthood.2 The factors influencing AD are complex. Researchers have conducted meta-analyses of the various factors correlating to the onset of AD in terms of external exposures, individual factors, mechanisms and other diseases, and proposed that factors related to microbiota and infant feeding may play a role in influencing the development of AD, including exclusive breast feeding or formula feeding, duration of breast feeding and timing of food introduction (figure 1 and online supplemental table S1). Some studies have reported that infants exclusively breastfed for more than 3–4 months are less likely to develop AD, especially in the first 4 months of life.3 However, the relationship between breast feeding and AD is controversial. In the Copenhagen longitudinal birth cohort, there was no significant association between the duration of exclusive breast feeding and the development of sensitisation in the first 6 years of life.4 A similar result was also found in Riyadh, where no associations were demonstrable between full or ever breast feeding …