Abstract
Postprandial lipemia and fatty acid fluxes occur several times daily, resulting in very efficient absorption of dietary fat and redistribution to various tissues. Absorbed dietary lipids are incorporated into chylomicrons to distribute triglycerides either for storage in adipose tissue or for immediate use in muscle. Commonly, the dietary sources of fat exceed the actual needs and the tissues are faced with dealing with the excess. Under these circumstances, the removal process of dietary triglycerides and fatty acids becomes overloaded, resulting in excessive postprandial lipemia and accumulation of chylomicrons, remnant particles and non-esterified fatty acids. These particles are associated with disruptions in lipoprotein metabolism and changes in inflammatory factors, thus their association with cardiovascular disease, metabolic syndrome and diabetes is not surprising. Dietary factors, not just fat, influence postprandial fluxes. This leads to the question: do we need a standardized fat tolerance test? The recognition of the factors influencing postprandial lipemia and fatty acid uptake and clearance is constantly increasing. Numerous proteins, transporters, enzymes and hormones have been shown to affect fatty acid flux at the level of absorption, peripheral uptake and hepatic remnant clearance. This summary targets fatty acid fluxes, with a focus on acylation-stimulating protein. Keywords: C3adesArg; lipoprotein lipase; postprandial; triglyceride
Highlights
Cianflone KIn addition to all of the acute components listed above, changes in dietary patterns and exercise before the fatload test may influence both fasting lipoproteins and postprandial fat responses
Postprandial lipemia and fatty acid fluxes occur several times daily, resulting in very efficient absorption of dietary fat and redistribution to various tissues
Lipoprotein lipase (LPL) localized to the endothelial cell surface within the capillaries binds to the chylomicrons, hydrolyzing the TGs to release glycerol and fatty acids for uptake and use or storage in adipose tissue
Summary
In addition to all of the acute components listed above, changes in dietary patterns and exercise before the fatload test may influence both fasting lipoproteins and postprandial fat responses. The LPL variant S447X, present in 18Á22% of individuals, results in alteration of the penultimate amino acid from serine to a stop codon This mutation is associated with increased LPL mass, but there are conflicting data and interpretations. Evaluation of postprandial fat clearance has demonstrated that this LPL variant is associated with attenuation of apoB48 and TG postprandial increases and increased preheparin LPL mass [12], consistent with a lower risk for cardiovascular disease. Variations in plasma apoCIII have been shown to be strong correlates of fasting and postprandial lipemia responses to high monounsaturated fatty acids and high-carbohydrate diets with increased levels of apoCIII associated with delayed postprandial TG clearance [15]. Differences in subject characteristics and maintenance diets as well as the total calories and composition of the fat loads probably contributed
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