Longitudinal profiling of human breast milk metabolome and its association with infant growth during early lactation

Human breast milk (HBM) is widely recognized as the optimal source of nutrition for infants. However, a comprehensive understanding of its dynamic metabolite profile, particularly beyond the first month of lactation and its association with infant growth remains limited. In this longitudinal study, we analyzed 186 HBM samples collected from 62 mothers at approximately 0.5, 1, and 3 months postpartum using LC-MS based untargeted metabolomics. We identified 67 metabolites with significant temporal changes, primarily from lipid, carbohydrate, amino acid, and energy metabolism pathways. Key dynamic trends included an initial rise and subsequent decline in polyunsaturated fatty acids and a progressive increase in lactose. Generalized estimating equations modeling revealed that specific metabolites, notably valine, creatine, and isocitric acid, were positively associated with infant growth (weight, length, and head circumference), while acetyl-L-carnitine showed a negative association. These findings delineate stage-specific adaptations in the HBM metabolome, providing a metabolite-driven framework to understand infant nutrition and to guide future strategies for precision nutrition. • Human milk metabolome reveals lipids as the dominant time-variant class. • Valine and creatine positively associate with infant growth. • LA and EpOME decline indicates stage-specific lipid metabolism. • Provides metabolomic evidence for targeted infant nutritional strategies.