Metabolomics-based comparative study of breast colostrum and mature breast milk

Breast milk is the safest and most complete natural food for babies. Although breast milk is crucial to the health and development of infants, the metabolites in breast milk during lactation period have not been characterized. Therefore, we examined and compared the metabolites in breast colostrum and mature breast milk using gas chromatography-time-of-flight-mass spectrometry-based metabolomics. A total of 159 metabolites were characterized, of which 72 were differentially expressed metabolites (DEMs), including 17 upregulated and 55 downregulated DEMs in breast colostrum compared to those in mature breast milk. Metabolic pathway analysis revealed that these DEMs were related to glycine, serine, and threonine metabolism; glyoxylate and dicarboxylate metabolism; alanine, aspartate, and glutamate metabolism; pentose and glucuronate interconversions; and aminoacyl-tRNA biosynthesis. Our results improve the understanding of breast milk composition and provide a theoretical basis for optimizing infant formula to closely imitate the nutrients required for proper growth and development of babies.