Pre-clinical and clinical studies of structured triacylglycerols (OPO and OPL) in human milk

Abstract: Breast milk is the best food for infant. Fats accounts for 3-5% of breast milk, but provides about 50% of the energy, as well as essential fatty acids, fat-soluble vitamins and some bioactive substances. Therefore, it is very important to simulate the lipids of breast milk. The structured triacyclglycerols i.e. OPO, OPL and LPL(O-oleic, P-palmitic, L-linoleic) existed in the human milk fat were systematically studied by pre-clinical and clinical models. In cell and in vitro digestion models, the final hydrolysis rate of structured lipids i.e. OPO and OPL were higher than that of LPL, and the average particle size of structural lipids were smaller, and the particles were more finely dispersed in the intestine. OPL, in higher content in Chinese breast milk, is more easily absorbed and transported in Caco-2 cells than OPO. In animal experiments, the effects of different proportions of OPO and OPL on lipid metabolism, inflammation, and gut microbiota in mice were explored. The results showed that compared with low level OPL, high level OPL (HOPL) diet improved lipid metabolism and gut microbiota and reduced the levels of pro-inflammatory cytokines in mice. SD rats with mixed OPO and OPL had the lowest liver and perirenal white fat weight, the lowest serum TG, TC, LDL levels, the highest absorption rate of fatty acid and calcium, and the highest content of free and bound bile acids in serum and intestinal contents. In terms of OPO clinical trial, through clinical intervention, feeding infants with OPO formula was beneficial to reduce the concentration of saponified fatty acids and fecal calcium content in infants' feces, increase the frequency of defecation, and reduce the frequency of crying. In general, the triacylglycerol structure and composition in breast milk have immense impact for the infants’ healthy growth and body development.