In vitro gastrointestinal lipid handling and bioaccessibility rate of infant formula with large phospholipid-coated lipid droplets are different from those of standard formula and closer to human milk

Background: Lipid droplet size and interfacial coating (protein or phospholipid) varies in early life nutrition and can impact gastrointestinal lipid handling, thereby affecting the rate at which free fatty acids and monoacylglycerides become potentially available for absorption (bioaccessible). We compared gastrointestinal handling and lipid bioaccessibility rates of infant formulas that varied in size and coating and human milk (HM). Methods: Infant dynamic digestion was simulated using tinyTIM with advanced gastric compartment. Gastrointestinal handling (lipid top layer formation, emptied lipid rates, bioaccessible lipid rates and enteroendocrine cholecystokinin secretions by Caco-2 cells) of standard IF (sIF), standard IF with added MFGM (sIFM) and concept IF (cIF, Nuturis®) with large, MFGM coated lipid droplets and HM were compared. Results: HM and cIF, both with large lipid droplets, formed an intragastric lipid top layer early during digestion, leading to delayed HM lipid gastric emptying compared to sIF. Gastric aggregate formation preceded lipid top layer formation for sIF, while sIFM remained homogeneous. sIF bioaccessible lipids elicited increased cholecystokinin secretion compared to HM and cIF. Both HM and cIF exhibited lower bioaccessible lipid rates than sIF, suggesting that lipolysis was slower with large lipid droplets. The addition of non-coating MFGM to the standard IF did not significantly impact gastrointestinal handling nor bioaccessibility rates. Conclusion: Gastrointestinal handling of cIF is different from sIF, resulting in a lower lipid bioaccessibility rate, which is closer to that of HM. A lower lipid bioaccessibility rate in early life may promote lipid oxidation over storage, benefiting metabolism, growth, and brain development.