Breast milk composition changes over time to provide infants with the nutrients needed to support growth and health, including functions like immune defense.  By monitoring changes in the proteome and peptidome in breast milk over time, it may be possible to gain insights into the maternal and infant relationship.  

The possibility of using new analytical techniques to better understand the changing composition of human milk motivated a study by Zhu and colleagues.  Results of that work are published in the April 2021 issue of The Journal of Nutrition.

Subjects in the study included two healthy milk donors.  They provided breast milk samples collected at weeks 1, 2, 3, 4, 6, 8, 10, 12, and 16 postpartum for analysis using quantitative LC-MS/MS methods.  Concentrations of over 1300 milk proteins and 2000 endogenous peptides were monitored.

In early lactation, both subjects had high concentrations of proteins and peptides involved in lactose synthesis and immune development.  They both exhibited gradual and similar changes over time.  However, there was a substantial change in the breast milk of one donor at week 6 that was thought to reflect inflammation or an infection.  These observations led the authors to conclude that it is possible to use these approaches to characterize breast milk over time in order to better appreciate its influence on infant development. 


Zhu J, Dingess KA, Mank M, Stahl B, Heck AJR.  Personalized profiling reveals donor- and lactation-specific trends in the human milk proteome and peptidome.  Journal of Nutrition, Volume 151, Issue 4, April 2021, Pages 826–839,

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