Research Progress on the Relationship Between Variations in Breast Milk Composition and Food Allergies in Children

The escalating global prevalence of infant food allergies (FA) imposes societal burdens and health risks, highlighting the importance of understanding breast milk (BM) composition in FA prevention and early intervention. As the latest systematic review summarizing molecular mechanisms and clinical evidence, it comprehensively addressed the relationship between FA pathogenesis and BM composition, including key metabolites (short-chain fatty acids [SCFAs], human milk oligosaccharides [HMOs], and free amino acids [FAAs]), fat-soluble vitamins, microbiota composition, and food allergens. Five main mechanisms were described as follows: (1) HMOs shape immune polarization through TLR4 signaling and Th cell balance regulation; (2) lipids mediate immune responses via SCFA-G protein-coupled receptor (GPCR) pathways and polyunsaturated fatty acids (PUFA)–dependent membrane effects; (3) FAAs sustain gut barrier function and modulate IgE responses through metabolic regulation; (4) fat-soluble vitamins maintain immune homeostasis through nuclear receptor signaling and mucosal maintenance; and (5) microbiota-HMO crosstalk generates tolerance-promoting metabolites. Interestingly, the amount of clinical evidence also indicated that certain BM components can be involved in regulating FA. These insights offered clinically actionable targets for precision nutrition and redefined BM as a dynamic immune-modulating ecosystem with stratified intervention potential.