Search

Lipids of human milk or infant formula convey most of the energy necessary to support the newborn growth. Until recently, infant formula chemical composition had been optimized but not their structure. And yet, more and more proofs of evidence have shown that lipids structure in human milk modulates digestion kinetics and is involved in metabolic programming. Indeed there is a striking difference of structure between human milk which is an emulsion based on dispersed milk fat globules (4 μm) secreted by the mammary gland and submicronic neoformed lipid droplets (0.5 μm) found in infant formula. These droplets result from a series of operation units. This difference of structure modifies digestion kinetics and emulsion disintegration in the intestinal tract of the newborn. This difference persists along gastric phase which is mainly dominated by acid and enzyme-induced aggregation. Lipid droplets size is thus the key parameter to control gastric lipolysis and emptying and intestinal lipolysis. This parameter also controls proteolysis since adsorbed proteins are more rapidly hydrolyzed than when in solution. In animal models, these differences of lipid structure would also impact digestive and immune systems' maturation and microbiota. Lipid structure during neonatal period would also be involved in the early programming of adipose tissues and metabolism. The supplementation of infant formulas with bovine milk fractions (milk fat globule membrane extracts, triacylglycerol) or recent development of large droplets infant formula, along with new fields of innovation in neonatal nutrition, are here reviewed.

Labrasol® and Gelucire® 44/14 are lipid-based excipients used for the oral drug delivery of poorly water-soluble drugs. These macrogolglycerides are composed of acylglycerols and PEG esters, potential substrates of digestive lipases. We developed an in vitro method to simulate the gastrointestinal lipolysis of these excipients and to evaluate the impact of lipolysis in vivo. At the end of the gastric phase, the composition of both excipients was significantly modified underlining the importance of gastric lipolysis in vivo. We also studied the influence of excipients’ lipolysis on the solubilization of a poorly water-soluble drug, cinnarizine, in aqueous phase. Gastrointestinal lipolysis of Labrasol® was a prerequisite to maintain cinnarizine in aqueous solution, whereas the lipolysis of Gelucire® 44/14 did not affect the cinnarizine solubilization.

Lipolytic enzymes have been associated with the city of Marseille ever since the 1940s. At that time, the biochemists established tight links with the Marseille School of Chemistry for investigating fat-splitting by enzymes, particularly the hydrolysis of triglycerides by lipases. Several important milestones on lipase research are associated with this long standing collaboration, from the molecular aspects of lipases to their physiological roles and their various medical and industrial applications. This story will be reviewed here through several highlights on pancreatic and gastric lipase research. Pancreatic lipase, which was for long the only lipase available for biochemical studies, still remains an attractive enzyme with the development of lipase inhibitors for obesity treatment. It is also used for enzyme replacement therapy in case of exocrine pancreatic insufficiency. Novel pancreatic lipaserelated proteins have been identified and their physiological roles now extend from fat digestion to lipoprotein metabolism, lipid signaling and innate immunity.