Metabolic impact of dietary lipids: towards a role of unabsorbed lipid residues?☆

The metabolic impact of dietary lipids needs to be considered beyond the fatty acid profile and energetic value of such lipids. Fatty acids are the building blocks of the different lipid molecules, including triacylglycerols and phospholipids, which are organized within various supramolecular structures such as emulsion droplets. These structures can also be naturally present or incorporated a posteriori in different food matrices. Gut health including its barrier function and microbiota is now recognized as a major player in cardiometabolic health. Even if more than 95% of dietary lipids are absorbed by the intestine to reach the bloodstream within the chylomicrons, a small proportion that is not absorbed is however able to interact with the microbiota and the cells of the distal intestine. The present non-exhaustive review will summarize briefly recent work on the impact of dietary lipids on absorption and their metabolic fate in the intestine, in particular on endotoxemia and low-grade inflammation related to obesity. Functional lipids are important ingredients used in food formulation and recent work has revealed the potential impact of some food emulsifiers on metabolism and inflammation in rodents in line with intestinal effects. Of particular interest in this review will be also recent findings on the benefits of dairy polar lipids on human lipid metabolism and their beneficial effects on metabolic inflammation in preclinical models. The review will also address the underlying mechanisms related to the metabolic fate of specific lipids such as sphingomyelin in the distal intestine, the microbiota and some actors of the intestinal barrier. Finally, these recent findings will be considered in the concept of the “food matrix effect” opening perspectives in the nutritional management of metabolic disorders.