Postprandial Triglyceride-rich Lipoprotein Composition and Size after Olive Oil
Publisher Summary The postprandial lipid period takes place after the intake of food. Therefore, postprandial lipid metabolism refers to the metabolic processes that occur following the ingestion of a meal containing fat, and it is characterized by a considerable increase in plasma triglyceride (TG) levels. The postprandial response can last up to 8 hours depending on the amount and type of ingested fat. Thus, due to the frequency of intake in developed countries, most humans are in an almost constant postprandial state. Together with elevated plasma TG, an impaired metabolism of postprandial triglyceride-rich lipoproteins (TRL) is believed to contribute to the onset and development of atherosclerosis. TRL comprise a very heterogeneous group of nascent and metabolically modified lipoproteins, including chylomicrons (CM), very-low-density lipoproteins (VLDL), and their remnants. CM are assembled in the intestine and mainly contain dietary lipids, while VLDL include lipids from endogenous origin. TRL become remnant particles after partial depletion of their TG content by lipoprotein lipase (LPL) hydrolysis. These types of particles are highly atherogenic because, in contrast to low-density lipoproteins, TRL can penetrate into the intima and be taken up by macrophages without need for prior oxidation, leading to foam cell formation, which is one of the first steps in atherosclerosis development. In addition, each TRL transports more cholesterol than does each particle of low-density lipoproteins (LDL), delivering to the intima 5- to 20-fold more cholesterol and therefore, being potentially more atherogenic than LDL. The atherogenicity of TRL is influenced by their composition and size, increasing the risk with the augmentation of circulating particles and the time elapsed before their clearance. One of the proposed reasons why dietary fats play a key role in atherogenesis is because dietary lipids contained in CM can interact directly with cells in the artery wall during their plasmatic transport.