EDB-IPP PhD Scholarship

Wilmar-NUS Economic Development Board – Industrial Postgraduate Programme (EDB-IPP)

Applications are welcome from eligible participants (Singapore citizens/PR only)

If interested, please contact Dr Amaury Cazenave Gassiot

Structural characterization of minor lipid components in breast milk

Breast milk is the optimal form of nutrition for infants. Lipid in breast milk is a highly complex mixture that provides not only energy, but also important components required for the baby’s healthy growth and development (1). With the advancement of mass spectrometry (MS), more in-depth structural characterization of the breast milk lipidome has been achieved in the last two decades. It has been recognized that the specific arrangement of fatty acids and other functional groups in lipid molecules are crucial for proper digestion and absorption in infants. The most well-known example is sn-2 palmitate triacylglycerols (2). In breast milk, more than 80% of palmitic acid (PA) is esterified at the sn-2 position of the glycerol backbone to facilitate its absorption in the form of 2-monoacylglycerol; whereas in plant oil-based and cow’s milk fat-based infant formulas, most of it is found at the outer sn-1/3 positions (3). Further research identified the specific structures and levels of sn-2 palmitate triacylglycerols in different geographical regions. Studies by high-resolution LC-MS pointed out that 1,3-olein-2-palmitin (OPO) is the most abundant triacylglycerol in Western mothers’ milk, while 1(3)-olein-2-palmitin-3(1)-linolein (OPL) is the most abundant in Chinese mothers’ milk (4). This example highlights the fact that breast milk lipid profiles may vary greatly between different regions. Therefore, to develop better human milk fat substitute, it is crucial to understand the structure and normal ranges of various lipid components in breast milk from different populations.

Macro lipid components of breast milk, such as triacylglycerols in the example above, have been studied extensively; however, much less work has been done for minor but highly bioactive components such as diacylglycerol ethers (DAGEs), glycerophospholipids, glycolipids, etc… For example, DAGEs has been demonstrated to sustain beige adipocytes and prevent childhood obesity (5); however, structural information of intact DAGEs in breast milk has not been reported in literature. In this project, we aim to develop novel analytical methods to extensively decipher the structures of these minor complex lipid components in breast milk from mothers of different ethnic backgrounds.

We will characterize these minor lipid classes using our state-of-the-art technologies such as high-resolution LC-MS and ion mobility MS. We will first explore various sample processing and chromatographic separation methods to optimally separate the lipid classes and the species within a class. Second, we will analyze them by tandem/ion mobility MS and build mathematical models to deconvolute co-eluting species down to regioisomer level, i.e. assigning sn- positions. Lastly, we will collect breast milk samples from mothers of three major ethnicities in Singapore (Chinese, Malay and Indian) and apply the developed workflow to determine their respective minor lipid profiles. This will strengthen the scientific knowledge on breast milk lipids and serve as a gold standard for developing human milk fat substitute.

References

1.          Lopez, C., and Ménard, O. (2011) Human milk fat globules: Polar lipid composition and in situ structural investigations revealing the heterogeneous distribution of proteins and the lateral segregation of sphingomyelin in the biological membrane. Colloids Surfaces B Biointerfaces. 83, 29–41

2.          Innis, S. M. (2011) Dietary Triacylglycerol Structure and Its Role in Infant Nutrition. Adv. Nutr. 2, 275–283

3.          López-López, A., López-Sabater, M., Campoy-Folgoso, C., Rivero-Urgell, M., and Castellote-Bargalló, A. (2002) Fatty acid and sn-2 fatty acid composition in human milk from Granada (Spain) and in infant formulas. Eur. J. Clin. Nutr. 56, 1242–1254

4.          Yuan, T., Qi, C., Dai, X., Xia, Y., Sun, C., Sun, J., Yu, R., Zhou, Q., Jin, Q., Wei, W., and Wang, X. (2019) Triacylglycerol Composition of Breast Milk during Different Lactation Stages. J. Agric. Food Chem. 67, 2272–2278

5.          Yu, H., Dilbaz, S., Coßmann, J., Hoang, A. C., Diedrich, V., Herwig, A., Harauma, A., Hoshi, Y., Moriguchi, T., Landgraf, K., Körner, A., Lucas, C., Brodesser, S., Balogh, L., Thuróczy, J., Karemore, G., Kuefner, M. S., Park, E. A., Rapp, C., Travers, J. B., and Röszer, T. (2019) Breast milk alkylglycerols sustain beige adipocytes through adipose tissue macrophages. J. Clin. Invest. 129, 2485–2499