Figure 4.

Breast milk lipids regulate fat metabolism. (A) Transmission electron microscopy image of a breast gland cell in lactating cattle. Lipid droplets are colored for better visibility. nc, nucleus; lp, lipid droplet (scale 2 μm). The scheme shows the morphology of the milk lipid droplets: it contains a triglyceride core (Core), which is surrounded by a single membrane layer of endoplasmic reticulum (ER), the cytoplasm (CP) and the plasma membrane (PM) of the gland cell. All of these compartments are rich in lipid species, and bear hallmarks of the maternal lipid profile [13], and transmit lipid signals from mother to child. For instance, breast milk ether lipids are used for synthesis of inflammatory lipid mediators in the neonate [119], which is believed to increase pathogen defense. Excess secretion of inflammatory lipid species into the breast milk can cause inflammatory disease in mice [120], and is believed to increase the development of chronic inflammatory diseases in human [41,121]. Breast milk lipid species are also responsible for proper adipose tissue development and functioning in the infant [12,19]. (B) Lipid species of breast milk that shape the development and function of adipocytes. AKGs, alkylglycerols; 12,13-diHOME, 12,13-dihydroxy-9Z-octadecenoic acid; EPA, eicosapentaenoic acid (ω-3 fatty acid); DHA, docosahexaenoic acid (ω-3 fatty acid).