Comparative Analysis of Lipid Composition of Infant Formula with Different Fat Sources and Human Milk

In this study, we performed a comparative analysis of the total fatty acid, sn-2 fatty acid and triglyceride composition of infant formula (IF) with four different fat sources and human milk. The results showed that a total of 27 fatty acids and 87 triglycerides were detected across all samples. Compared with human milk, the four IFs contained more saturated fatty acids and less polyunsaturated fatty acids. More than 70% of the saturated fatty acids in human milk were esterified at the sn-2 position of triglycerides, whereas the sn-2 position of triglycerides in the four IFs was mostly occupied by unsaturated fatty acids, especially vegetable oil-based IF1 and IF2, with 80% sn-2 unsaturated fatty acids. In terms of triglyceride composition, the contents of 1-oleic acid-2-palmitate-3-linoleic acid triglyceride (OPL), 1,3-dioleic acid-2-palmitic acid triglyceride (OPO) and some medium and long-chain triglycerides in human milk were significantly higher than those in the IFs (P < 0.05), while the IFs contained more triolein (OOO), 1-oleic acid-2,3- linoleic acid triglycerides (OLL) and some medium-chain triglycerides (P < 0.05). Different fat sources could significantly affect the lipid composition of IF. IF1 and IF2 had similar triglyceride and fatty acid composition and distribution. They were clearly distinguished from IF3 and IF4 with added milk fat, and milk/vegetable oil mixed-based IF was closer to human milk in terms of overall lipid composition. Finally, based on multivariate analysis, a total of 16 triglycerides were found to useful to discriminate between human milk and infant formula. The results reported herein are useful in designing new milk formula that can better mimic human milk.