Compositional differences between preterm milk of different gestational ages with the term milk: a comparative lipidomic study by LC-MS/MS

Abstract

Background Studies are beginning to emerge on the important biological effects of the milk lipids exerted on the recipient infant, especially on the premature infants. The aim of this study was to comprehensively describe lipidomic differences between preterm milk of different gestational ages with the term milk over the course of lactation. Methods Breast milk samples were collected from 88 mothers giving birth prematurely and 39 mothers delivering at full-term (FT). Lipid profiles were assessed using an LC-MS/MS metabolomics strategy. Orthogonal partial least-squares discriminant analysis (OPLS-DA) and pathway analysis were subsequently performed. Results The OPLS-DA score plots significantly distinguished the lipids in preterm milk of different gestation ages from their counterparts in term milk. The concentrations of 10 out of 43 lipid subclasses were found to be persistently higher in preterm compared to term milk over the course of lactation; the diacylglycerol (DAG) and a bioactive subclass fatty acid ester of hydroxyl fatty acid (FAHFA) contributed the most to the differences. In terms of individual lipid species, the ten highest substances found in very preterm (VPT) colostrum compared to FT colostrum mainly come from the phosphatidylethanolamine class and the DAG species. Lipid species from the free fatty acid and FAHFA classes were significantly higher in either extremely preterm (EPT) or VPT mature milk (variable importance in projection > 1, P < 0.0001 for all). The differential lipids between each preterm group and its term counterpart were predicted to be mainly involved in six metabolic pathways, including glycerophospholipid metabolism, glycosylphosphatidylinositol (GPI)-anchor biosynthesis, linoleic acid metabolism, alpha-Linolenic acid metabolism, arachidonic acid metabolism and glycerolipid metabolism. Conclusions The lipids in preterm and term milk showed substantial differences, which may be critical for postnatal growth, as well as the neural and immune development of newborns, especially EPT and VPT.