Exploring Minor Proteins and Peptides in Human Milk: a Proteomic Analysis Across Lactation Stages

Human milk (HM) is the optimal food source for the nutrition, growth, and development of newborns. The protein fraction of HM plays a crucial role in the healthy development of infants. HM contains a wide variety of minor whey proteins and peptides with important bioactive functions, many of which are still unknown. Proteomics allows for the study of biological samples with inherently complex protein mixtures. Proteins are essential for the development of living organisms, both in quantitative and qualitative terms. The combination of proteomic techniques currently enables the study of protein variability and minor peptides in HM across different lactation stages and allows for differential quantification according to gestational age and birth weight. However, studies on the human milk serum proteome during these stages are limited. The aim is to explore the minor whey proteins and peptides in human milk through a longitudinal analysis of five groups of breastfeeding mothers (with 30 extremely low birth weight newborns, 30 very low birth weight newborns, 30 low birth weight newborns, 30 adequate birth weight newborns, and 30 high birth weight newborns). Gestational age will also be considered to ensure homogeneous group distribution according to this condition. HM samples will be collected from each mother during three lactation periods after birth: within the first 48 hours (colostrum), at 5-14 days (transitional milk), and at 100-120 days (mature milk) for the five birth weight groups. In these neonatal/infant groups, minor proteins from whey fraction and peptides will be separated, quantified, and identified using label-free proteomic techniques. This study aims to expand our understanding of the minor proteins and peptides in human milk and their bioactive roles in neonatal health. By examining these components across different birth weight groups and lactation stages, the research will offer insights into how protein and peptide profiles vary by gestational age and birth weight, potentially influencing neonatal development. The findings from this proteomic analysis could not only demonstrate the complexity of human milk composition but also contribute to targeted nutritional support for preterm or low-birth-weight infants, customizing protein supplementation in HM banks and therefore enhancing their growth and developmental outcomes.