Postprandial Triacylglycerols from Dietary Virgin Olive Oil Are Selectively Cleared in Humans

Abstract

The aims of the present study were to evaluate the effect of a meal rich in virgin olive oil on triacylglycerol composition of human postprandial triacylglycerol-rich lipoproteins (fraction Sf > 400), and to assess the role of the triacylglycerol molecular species concentration and polarity on lipoprotein clearance. Fasting (0 h) and postprandial blood samples were collected hourly for 7 h from eight healthy normolipidemic subjects after the ingestion of the meal. Plasma and lipoprotein triacylglycerol concentrations increased quickly over fasting values and peaked twice at 2 and 6 h during the 7-h postprandial period. The triacylglycerols in the lipoprotein fraction at 2 h generally reflected the composition of the olive oil, however, the proportions of the individualmolecular species were altered by the processes leading to their formation. Among the major triacylglycerols, the proportion of triolein (OOO; 43.6%) decreased (P < 0.05), palmitoyl-dioleoyl-glycerol (POO; 31. 1%) and stearoyl-dioleoyl-glycerol (SOO; 2.1%) were maintained and linoleoyl-dioleoyl-glycerol (LOO; 11.4%) and palmitoyl-oleoyl-linoleoyl-glycerol (POL; 4.6%) significantly increased (P < 0.05) compared with the composition of the triacylglycerols in the olive oil. Smaller amounts of endogenous triacylglycerol (0.8%), mainly constituted of the saturated myristic (14:0)and palmitic (16:0) fatty acids, were also identified. Analysis of total fatty acids suggested the presence of molecular species composed of long-chain polyunsaturated fatty acids of the (n-3) family, docosapentaenoic acid, [22:5(n-3)] and docosahexaenoic acid (DHA), [22:6(n-3)] and of the (n-6) family [arachidonic acid, [20:4(n-6)]. The fastest conversion of lipoproteins to remnants occurred from 2 to 4 h and was directly related to the concentration of the triacylglycerols in the lipoprotein particle (r = 0.9969, P < 0.05) and not with its polarity (r = 0.1769, P > 0.05). The rates of clearance were significantly different among the major triacylglycerols (OOO, POO, OOL and POL) (P < 0.05) and among the latter ones and PLL (palmitoyl-dilinoleoyl-glycerol, POS (palmitoyl-oleoyl-stearoyl-glycerol) and OLL (oleoyl-dilinoleoyl-glycerol) (P < 0.01). OOO was removed faster and was followed by POO, OOL, POL, PPO (dipalmitoyl-oleoyl-glycerol), SOO, PLL, POS and OLL.

Triglycerides and Cardiovascular Disease

“…For example, a meal that contained up to 15 g of fat was associated with minimal (20%) increases in peak ppTG levels, 276 whereas high-fat meals (eg, 50 g), including those served in popular fast-food restaurants, increased triglyceride levels by at least 50% beyond fasting levels. 68,273,275,279 Because median triglyceride levels in US adults range between 106 (women) and 122 (men) mg/dL, measurement of nonfasting triglyceride levels in the absence of a high-fat meal (eg, Ͻ15 g) would be expected to eliminate the requirement for a fasting lipid panel in a sizeable proportion of otherwise healthy adults. A practical algorithm for screening triglyceride measurements is suggested in Figure 5.…”

Digestion and absorption of olive oil

“…It has been shown a linear correlation between the presence of linoleic acid at the sn-2 position (but not in other stereospecific positions) of triglyceride molecule and the plasma level of arachidonic acid (20:4n-6), indicating that only sn-2 position is maintained throughout the absorption and remaining metabolic processes (Renaud et al, 1995). In olive oil, up to 95% of total fatty acids at the sn-2 position are MUFA, mainly oleic acid, which means that olive oil acts as a supplier of oleic acid-rich hydrocarbon skeletons for cellular synthesis of triglycerides and phospholipids (Abia et al, 1999).…”

Blood transport and genomic effects of olive oil components

“…Oleic acid (18:1n-9) is the main fatty acid found in the phospholipids of postprandial triglyceride-rich lipoproteins after a meal rich in olive oil, whereas stearic (18:0) and linoleic (18:2n-6) acids are those found with a meal rich in high-oleic sunflower oil and exhibit higher time of clearance. This metabolic process is also regulated by the nature of carried triglycerides, being more quickly removed OOO (triolein) followed by POO (palmitoyl-dioleoyl glycerol) and OOL (dioleoyl-linoleoyl glycerol) (Abia et al, 1999).…”

“…Throughout the postprandial metabolism, the liver secretes new triglyceride-rich lipoproteins (VLDL) to the blood circulation. This process occurs usually after 5-6 hours post-meal period (Abia et al, 1999).…”