Modulation of the effects of chylomicron remnants on endothelial function by minor dietary lipid components

There is emerging evidence that minor components from dietary oils can modulate or even improve events occurring in the development of atherosclerosis. One of the earliest events of the atherosclerotic process is endothelial dysfunction, which is an activation of the endothelium manifested by an increase in proinflammatory molecules, such as cytokines and adhesion molecules. Chylomicron remnants, such as LDL (low-density lipoprotein), are considered to be pro-atherogenic lipoproteins because they interact with endothelial cells and macrophages, increasing endothelial dysfunction mainly by the disturbance of the redox state in the cell. However, chylomicrons are, at the same time, the natural carriers of dietary lipids in plasma, which gives minor lipid components the opportunity to interact with the cells implicated in endothelial dysfunction and atherogenesis. Some of these components are known to exhibit antioxidant, anti-inflammatory and anti-atherogenic effects in vitro, even forming part of triacylglycerol-rich lipoproteins, such as chylomicrons.Peer reviewe

Influence of minor components of olive oils on the composition and size of TRLs and on macrophage receptors involved in foam cell formation.

Metabolic and epidemiologic studies support the idea that the type of dietary fat is more important than the total amount of fat with respect to the development of atherosclerosis and the risk of cardiovascular heart disease. Dietary fat is carried in CMs (chylomicrons), which can be taken up by macrophages without need of further oxidation, leading to the formation of foam cells and initiating or aggravating the atherogenic process. Evidence from different studies has shown that dietary fat can influence the composition and size of TRLs (triacylglycerol-rich lipoproteins), which might modulate their atherogenicity to a certain extent. In particular, experiments in vitro have shown the anti-atherogenic effects of minor components from olive oil when forming part of TRL, as these particles give minor lipid components the opportunity to interact with the cells implicated in endothelial dysfunction and atherogenesis. However, the exact mechanisms mediating CM uptake by macrophages still remain unclear. Thus further studies are needed to understand how the modifications of TRL composition caused by dietary fats could modulate the expression of macrophage receptors and foam cell formation, or even improve the atherogenic risk of these particles.Peer reviewe

The role of virgin olive oil components in the modulation of endothelial function

The endothelium is involved in many of the processes related to the development of atherosclerosis, which is considered an inflammatory disease. Actually, traditional risk factors for atherosclerosis predispose to endothelial dysfunction, which is manifested as an increase in the expression of specific cytokines and adhesion molecules. There are firm evidence supporting the beneficial effects of olive oil, the most genuine component of the Mediterranean diet. Although the effects of olive oil and other oleic acid-rich dietary oils on atherosclerosis and plasma lipids are well known, the roles of minor components have been less investigated. Minor components constitute only 1–2% of virgin olive oil (VOO) and are composed of hydrocarbons, polyphenols, tocopherols, sterols, triterpenoids and other components usually found in traces. Despite their low concentration, non-fatty acid constituents may be of importance because studies comparing monounsaturated dietary oils have reported different effects on cardiovascular disease. Most of these compounds have demonstrated antioxidant, anti-inflammatory and hypolipidemic properties. In this review, we summarize current knowledge on the effects of these compounds contained in VOO on vascular dysfunction and the mechanisms by which they modulate endothelial activity. Such mechanisms involve the release of nitric oxide, eicosanoids (prostaglandins and leukotrienes) and adhesion molecules, in most cases by activation of nuclear factor κB by reactive oxygen species.Peer reviewe

Minor components of olive oil facilitate the triglyceride clearance from postprandial lipoproteins in a polarity-dependent manner in healthy men

Postprandial triglyceride-rich lipoproteins (TRLs) are recognized as atherogenic particles whose lipid composition and function can be modified by the composition of dietary oils. This study was designed to test the hypothesis that minor components of pomace olive oil (POMACE) can not only change the composition of postprandial TRL but also affect the clearance of triglyceride (TG) molecular species of postprandial TRL. Meals enriched in either POMACE or refined olive oil (OLIVE) were administered to 10 healthy young men. TRL were isolated from serum at 2, 4, and 6 hours postprandially, and their fatty acid and TG molecular species compositions were analyzed by gas chromatography. The apolipoprotein B concentration was determined by immunoturbidimetry. POMACE and OLIVE, differing mainly in their unsaponifiable fraction, led to similar fatty acid and TG molecular species profiles in postprandial TRL. However, POMACE-TRL presented a higher particle size, estimated as TG to apolipoprotein B ratio, which was also found for the main TG molecular species (trioleoyl-glycerol, palmitoyl-dioleoyl-glycerol, palmitoyl-oeloyl-linoleoyl-glycerol, and dioleoyl-linoleoyl-glycerol). TG from POMACE-TRL also showed higher clearance rates. In this regard, apolar TG (with a higher equivalent carbon number) disappeared more rapidly from TRL particles obtained after the ingestion of either POMACE or OLIVE. In conclusion, minor components of POMACE facilitated TG clearance from TRL by modifying their particle size and the hydrolysis of the most apolar species. © 2014 Elsevier Inc.This work was supported by funds from Comisión Interministerial de Ciencia y Tecnología (AGL2011-23810). The authors declare no conflicts of interest.Peer Reviewe

Pomace Olive Oil and Endothelial Function

Virgin olive oil, as the main fat source of the Mediterranean diet, has been proposed as one of the healthiest dietary oils, since there is increasing evidence demonstrating beneficial effects on the pathophysiology of atherosclerosis. Certainly, a number of experimental studies have revealed that virgin olive oil consumption can have favorable effects on hypercholesterolemia and hypertension. Traditionally the beneficial effect of virgin olive oil was ascribed to its fatty acid composition and the high monounsaturated fatty acid content. However, it has been demonstrated that minor components also have a very relevant role. In this regard, second-centrifugation pomace olive oil is particularly rich in some minor components with an elevated biological activity. Despite being devoid of polyphenols, the concentration of sterols and tocopherols is higher in pomace olive oil. In addition, pomace olive oil contains relevant amounts of triterpenic compounds, like the oleanolic and maslinic acids and the erythrodiol and uvaol alcohols, which have been related with the improvement in endothelial dysfunction in hypertensive animals. Although there is still a lack of clinical studies, pomace olive oil is emerging as a healthy dietary oil, with important implications in endothelial dysfunction, one of the first events occurring during the development of atherosclerosis

Postprandial Triglyceride-rich Lipoprotein Composition and Size after Olive Oil

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

Modifications in Postprandial Triglyceride-Rich Lipoprotein Composition and Size after the Intake of Pomace Olive Oil

OBJECTIVE: This study was designed to determine the composition of postprandial triglyceride-rich lipoproteins (TRL) after the intake of pomace olive oil (POO), which is a subproduct of the extraction of virgin olive oil (VOO) and presents a high concentration of minor components with biological activity. METHODS: Meals enriched in POO and refined olive oil (ROO) were administrated to 9 healthy young men and blood was extracted every hour during a postprandial period of 7 hours. Serum and TRL lipid composition were measured by enzymatic and chromatographic methods and apolipoprotein B composition by SDS-PAGE. RESULTS: POO and ROO showed a very similar fatty acid composition but differed in their unsaponifiable fraction. The content of phytosterols, tocopherols, terpenic acids and alcohols and fatty alcohols was much higher in POO than in ROO. Serum lipids were not affected by the administration of the oils but the triglyceride concentration in TRL and the size of the particles (p < 0.05) after POO was higher at time point 2 h and lower at time point 4 h compared with ROO. In contrast, the number of TRL particles was lower after POO, although the rate of clearance was similar. CONCLUSION: We suggest that the unsaponifiable fraction between the two olive oils affect the size and composition of postprandial TRL, which might have a relevant impact on their atherogenicity.This work was supported by funds from Comision Interministerial de Ciencia y Tecnologia (CYCIT, AGL2002-00195 and AGL2005-00572), a FPI fellowship (Ministerio de Educación y Ciencia) to RCM and a Juan de la Cierva contract to JSP.Peer reviewe

Efectos de la fraccion insaponificable del aceite de orujo sobre la composición lipidica de lipoproteínas ricas en triglicéridos postprandiales

Trabajo presentado en el II Congreso FESNAD. Federación Española de Sociedades de Nutrición Alimentación y Dietética, celebrado en Barcelona (España) del 03 a 05 de Marzo de 201