Bioactive compounds in pomace olive oil modulate the inflammatory response elicited by postprandial triglyceride-rich lipoproteins in BV-2 cells.

Modulation of microglial response could be a target to reduce neuroinflammation associated with Alzheimer's disease. In this study, we propose that lipophilic bioactive molecules present in pomace olive oil (POO), transported in triglyceride-rich lipoproteins (TRLs), are able to modulate microglial high-oleic sunflower oil (HOSO, points) or pomace olive oil (POO, stripes). In order to prove this hypothesis, a randomized crossover postprandial trial was performed in 18 healthy young women. POO was assayed in opposition to high-oleic sunflower oil (HOSO), a common dietary oil which shares with POO an almost identical fatty acid composition but lacks certain biomolecules with recognized antioxidant and anti-inflammatory activities. TRLs were isolated from blood at the baseline and 2 and 4 hours postprandially and used to treat BV-2 cells to assess their ability to modulate the microglial function. We found that the intake of POO leads to the constitution of postprandial TRLs that are able to modulate the inflammatory response in microglia compared to HOSO. TRL-derived POO reduced the release of pro-inflammatory cytokines (tumor necrosis factor-α, and interleukins 1ß and 6) and nitric oxide and downregulated genes codifying for these cytokines and inducible nitric oxide synthase (iNOS) in BV-2 cells. Moreover, the ingestion of POO by healthy women slightly improved glycemic control and TRL clearance throughout the postprandial phase compared to HOSO. In conclusion, we demonstrated that consuming POO results in postprandial TRLs containing lipophilic bioactive compounds capable of regulating the inflammatory response prompted by microglial activation.

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.

Evaluation of the effect of dietary virgin olive oil on blood pressure and lipid composition of serum and low-density lipoprotein in elderly type 2 diabetic subjects.

Dietary virgin olive oil may help to reduce blood pressure in hypertensive individuals, but little is known about the effect on type 2 diabetic patients. For the present study, 17 type 2 diabetic elderly subjects and 23 healthy elderly controls received a diet rich in virgin olive oil for 4 weeks. Blood pressure, biochemical parameters, low-density lipoprotein (LDL), and oxidized LDL lipids and fatty acids were measured. Systolic blood pressure was reduced after virgin olive oil consumption in both controls and diabetic patients. Although the biochemical parameters were not modified, the intervention protected LDL from oxidation and restored the levels of dihomo-gamma-linolenic acid (20:3, n-6) in serum cholesterol esters and phospholipids of diabetic patients. In conclusion, the present study provides new evidence of the effects of dietary virgin olive oil on blood pressure and LDL oxidation in type 2 diabetics. It is likely that the components responsible for the observed effects are the monounsaturated fatty acids and the presence of antioxidants in the oil, but this needs further investigation.

Consumption of virgin olive oil influences membrane lipid composition and regulates intracellular signaling in elderly adults with type 2 diabetes mellitus.

We aimed to define changes in membrane fatty acids and signaling proteins induced by virgin olive oil (VOO) consumption in elderly persons with type 2 diabetes (n = 16) compared to a control group (n = 28). The fatty acid composition was determined by gas chromatography and G-protein subunits and protein kinase C alpha (PKCalpha) by immunoblotting. VOO consumption increased the monounsaturated fatty acid content in phospholipids and cholesterol esters in both groups. In contrast, saturated fatty acids were decreased only in phospholipids. The levels of Galphao, Gbeta, and PKCalpha were significantly lower in diabetics than in controls. However, whereas VOO consumption reduced Galphas, Gbeta, and PKCalpha in both groups, reduction in Galphai was observed only in diabetics. These results indicate that long-term VOO consumption modifies the fatty acid composition of plasma membrane, which influences the association of G proteins and PKCalpha with the lipid bilayer. These combined effects probably account for the positive effects of VOO on glycemic homeostasis.

Virgin olive oil reduces blood pressure in hypertensive elderly subjects.

BACKGROUND & AIMS: Hypertension is one of the most important risk factors for coronary heart disease. Recent studies have pointed out the possibility that virgin olive oil (VOO) may lower blood pressure in hypertensive (HT) subjects. However, until the date there is scarce information regarding elderly people. The present study was designed to assess the effect of dietary VOO on blood pressure in medically treated hypertensive elderly patients. METHODS: 31 medically treated HT elderly patients and 31 normotensive (NT) elderly volunteers participated in a randomized sequential dietary intervention. Subjects consumed diets enriched in sunflower oil (SO) or VOO for 4 weeks each with a 4-week washout period between them. RESULTS: VOO reduced total and LDL-cholesterol in NT but not in HT (P < 0.01) and the concentrations were lower than in the group consuming SO. In contrast, no significant differences were found in the levels of tocopherols among the groups studied. Iron-induced oxidation of LDL resulted in a complete loss of monoacylglycerols (MG) and diacylglycerols (DG) and a reduction in triacylglycerols (TG) (60-80%), which was found to be greater in HT (P < 0.01) with no effect of diet. VOO consumption normalized systolic pressure in the HT group (136 +/- 10 mmHg) compared to SO (150 +/- 8 mmHg). CONCLUSION: Dietary VOO proved to be helpful in reducing the systolic pressure of treated HT elderly subjects. However, a greater resistance to the lowering effect of VOO of total and LDL-cholesterol and a greater susceptibility to TG oxidation was detected in these patients.

Plasma lipid modifications in elderly people after administration of two virgin olive oils of the same variety (Olea europaea var. hojiblanca) with different triacylglycerol composition.

In the present study we examined whether two virgin olive oils (VOO1 and VOO2), of the same variety (Olea europaea var. hojiblanca with a similar composition of minor components but differing in the content of triacylglycerol molecular species, had different effects on blood pressure and plasma lipid levels in a healthy elderly population. Thirty-one participants, aged 84-9 (SD 6.4) years, were asked to participate in the study. No differences were found with regard to blood pressure after both experimental periods (VOO1 and VOO2). However, plasma total cholesterol and LDL-cholesterol were reduced only after VOO1 (P<0.01). The reduction of plasma cholesterol concentrations was related to the incorporation of oleic acid into plasma cholesteryl esters and phospholipids strongly correlated with plasma total cholesterol and LDL-cholesterol levels in all experimental periods studied (r2>0.418, P<0.07), except for phospholipids in VOO1 (P=0.130 for total cholesterol and p=0.360 for LDL-cholesterol). These results have demonstrated that blood pressure and plasma lipids can be modified by the consumption of VOO in elderly people, but that the extent of such modification depends on the composition and amount of active minor components and triacylglycerol molecular species.

Distribution of fatty acids from dietary oils into phospholipid classes of triacylglycerol-rich lipoproteins in healthy subjects.

Several studies have suggested that lipoprotein metabolism can be affected by lipoprotein phospholipid composition. We investigated the effect of virgin olive oil (VOO) and high-oleic sunflower oil (HOSO) intake on the distribution of fatty acids in triacylglycerols (TG), cholesteryl esters (CE) and phospholipid (PL) classes of triacylglycerol-rich lipoproteins (TRL) from normolipidemic males throughout a 7 h postprandial metabolism. Particularly, changes in oleic acid (18:1n-9) concentration of PL were used as a marker of in vivo hydrolysis of TRL external monolayer. Both oils equally promoted the incorporation of oleic acid into the TG and CE of postprandial TRL. However, PL was enriched in oleic acid (18:1n-9) and n-3 polyunsaturated fatty acids (PUFA) after VOO meal, whereas in stearic (18:0) and linoleic (18:2n-6) acids after HOSO meal. We also found that VOO produced TRL which PL 18:1n-9 content was dramatically reduced along the postprandial period. We conclude that the fatty acid composition of PL can be a crucial determinant for the clearance of TRL during the postprandial metabolism of fats.

Triacylglycerol-rich lipoproteins trigger the phosphorylation of extracellular-signal regulated kinases in vascular cells.

Postprandial triacylglycerol-rich lipoproteins (TRL) have been implicated in the pathophysiology of atherosclerosis, but the intracellular processes by which TRL could affect vascular function are still unknown. Incubation of TRL obtained at 2 h postprandial period with vascular smooth muscle cells (VSMC) produced a tyrosine phosphorylation of the extracellular signal-regulated kinases 1 and 2 (ERK1 and ERK2) that belong to the mitogen-activated protein kinase (MAPK) family. The activation of ERK1 and ERK2 had a maximum at 15 min, returned to baseline by 60 min, and was partially depleted after incubation of cells with a MAPKK inhibitor (PD 098059). In addition, postprandial TRL did competent VSMC for DNA replication through a MAPK pathway. These effects were dependent of the lipid composition of TRL. Our observations suggest that postprandial TRL can trigger activation of the MAPK pathway and induce a mitogenic response in VSMC in a lipid-dependent fashion.