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.     

The metabolic availability of dietary triacylglycerols from two high oleic oils during the postprandial period does not depend on the amount of oleic acid ingested by healthy men

Monounsaturated oils, virgin olive oil (VOO) and high oleic sunflower oil (HOSO) are suggested to have selective physiologic effects on humans in the fasting state. The aim of the study was to evaluate whether two oils with equal amounts of oleic acid but with different compositions of minor fatty acids and triacylglycerol molecular species (TAG) could produce different triacylglycerol-rich lipoprotein (TRL)-TAG responses in the postprandial state. Eight normolipidemic men consumed the following three meals in random order on separate occasions with 2 wk between meals: control meal, control meal plus VOO and control meal plus HOSO. Plasma total TAG and TRL-TAG were measured hourly for 7 h after ingestion. TAG and sn-2 positional fatty acids within TAG were analyzed in the TRL fraction. Plasma total TAG concentrations in response to the dietary oils did not differ. However, TRL triglyceridemia was significantly lower after VOO intake (P < 0.05). The molecular species in the TRL fraction returned toward basal levels more quickly (P < 0.05) after VOO than HOSO intake. 2-Positional fatty acid analysis demonstrated higher proportions of stearic and palmitic acids and a lower proportion of oleic acid (P < 0.05) in TRL-TAG derived from HOSO. This study shows that VOO intake results in attenuated postprandial TAG concentration and faster TRL-TAG disappearance from blood compared with HOSO, suggesting that the oleic acid content may not be the main factor affecting TAG metabolism. Minor fatty acids such as linoleic acid and the 2-positional distribution of saturated stearic and palmitic acids into the TAG molecule may be important determinants of postprandial lipemia in normolipidemic men.     

Dietary oils high in oleic acid but with different unsaponifiable fraction contents have different effects in fatty acid composition and peroxidation in rabbit LDL

OBJECTIVE: We investigated the influence of different edible oils high in oleic acid but with different unsaponifiable fractions on the fatty acid composition and lipid peroxidation in plasma and low-density lipoprotein (LDL) in rabbits. METHODS: Thirty-two rabbits were randomly assigned to four groups of eight animals. For 8 wk each group was fed a semisynthetic isoenergetic diet that differed by lipid source (Picual virgin olive oil, Picual virgin olive oil that had been subjected to an exhaustive process of washing, Arbequina virgin olive oil, and sunflower oil high in oleic acid). We analyzed the fatty acid profile, thiobarbituric acid reactive substances, alpha-tocopherol, coenzyme Q, and retinol in plasma and the fatty acid profile, hydroperoxides, alpha-tocopherol, and coenzyme Q in LDL. RESULTS: The two varieties of virgin olive oil behaved differently from the high-oleic sunflower oil, and the effect of the different ratios of oleic acid to linoleic acid in the lipid sources on fatty acid composition in plasma and LDL was significant. With regard to oxidative stress, LDL in the group that ingested the lipid sources with the greatest amount of phenolic compounds showed the highest level of antioxidants (alpha-tocopherol and coenzyme Q; P < 0.05) and the lowest susceptibility to lipid peroxidation (P < 0.05). CONCLUSION: This study provides evidence in vivo of the considerable antioxidant capacity of the phenolic fraction of virgin olive oil in rabbit LDL and the important role that this unsaponifiable fraction can play in the overall antioxidant benefit attributed to these oils. However, these effects depend on the phenolic content of the oil.     

Microarray analysis of hepatic genes differentially expressed in the presence of the unsaponifiable fraction of olive oil in apolipoprotein E-deficient mice

The hypothesis that the unsaponifiable fraction of olive oil dramatically influences hepatic gene expression was tested in mice. Two olive oils, obtained from the same olive cultivar but by different technological procedures, were characterized to show that they differed mainly in terms of the composition/quantity of this unsaponifiable fraction. Using DNA microarrays, hepatic gene expression was analysed in apoE-deficient mice fed one of two isoenergetic, isonitrogenous diets containing either 10 % (w/w) olive oil or unsaponifiable fraction-enriched olive oil. To provide an initial screening of potential candidate genes involved in a differential response, only genes with remarkably modified expression (signal log2 ratio >3 or < - 3) were further considered. The eleven genes fulfilling these prerequisites were confirmed by quantitative RT-PCR, and then analysed in apoE-deficient mice with a C57BL/6J genetic background. Orosomucoid and serum amyloid A2 were upregulated (to variable extents depending on the genetic background) in the absence of hepatic steatosis and inflammation. Fabp5 and Mt2 were also strongly upregulated. Several proteases were highly suppressed by the unsaponifiable-enriched olive diet, independent of the genetic background. The findings indicate that change in the expression of these genes is a good marker of the intake of the unsaponifiable fraction of olive oil. The results highlight the important biological effects of the unsaponifiable fraction of olive oil. The term 'monounsaturated fatty acid-enriched oil' no longer appears appropriate for describing all the oils to which it is currently applied since it does not adequately reflect that they have different biological effects.     

Postprandial triacylglycerols from dietary virgin olive oil are selectively cleared in humans

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.     

Influence of dietary fat on oxidative stress and inflammation in murine macrophages

ObjectiveMany studies have shown that the nature of the lipid consumed in the diet significantly affects the development of inflammatory diseases. In this study, we compared the effect of diets supplemented with 15% by weight of fish oil (FO), refined olive oil (ROO), and pomace olive oil (POO) with that of a low-fat diet, 2% by weight of corn oil, considered as the basal diet (BD), on the ability to modify reactive oxidative species and proinflammatory mediator generation by stimulated murine macrophages.MethodsMice were fed the different oil-enriched diets for 8 wk. Peritoneal macrophages were isolated from these mice and subsequently stimulated. Reactive oxygen species and proinflammatory mediators were measured in the corresponding supernatants. Data were statistically treated by one-way analysis of variance and Tukey's multiple comparison post hoc test.ResultsThe ROO and POO significantly reduced the hydrogen peroxide production compared with BD, whereas FO stimulated its production. Moreover, the generation of nitric oxide was significantly prevented in all the experimental oil-enriched dietary groups. The ROO and FO groups showed significantly reduced cytokine (tumor necrosis factor-α, interleukin-1β, interleukin-6) and prostaglandin E₂ production.ConclusionThese results confirm the prevention action on proinflammatory mediator generation exerted by FO and demonstrate the protective antioxidant properties not only of olive oil but also of POO. The consumption of these olive oils may help to prevent cellular oxidative stress and inflammation.     

Dietary oleic and palmitic acids modulate the ratio of triacylglycerols to cholesterol in postprandial triacylglycerol-rich lipoproteins in men and cell viability and cycling in human monocytes

The postprandial metabolism of dietary fats produces triacylglycerol (TG)-rich lipoproteins (TRL) that could interact with circulating cells. We investigated whether the ratios of oleic:palmitic acid and monounsaturated fatty acids (MUFA):SFA in the diet affect the ratio of TG:cholesterol (CHOL) in postprandial TRL of healthy men. The ability of postprandial TRL at 3 h (early postprandial period) and 5 h (late postprandial period) to affect cell viability and cycle in the THP-1 human monocytic cell line was also determined. In a randomized, crossover experiment, 14 healthy volunteers (Caucasian men) ate meals enriched (50 g/m(2) body surface area) in refined olive oil, high-palmitic sunflower oil, butter, and a mixture of vegetable and fish oils, which had ratios of oleic:palmitic acid (MUFA:SFA) of 6.83 (5.43), 2.36 (2.42), 0.82 (0.48), and 13.81 (7.08), respectively. The ratio of TG:CHOL in postprandial TRL was inversely correlated (r = -0.89 to -0.99) with the ratio of oleic:palmitic acid and with the MUFA:SFA ratio in the dietary fats (P < 0.05). Postprandial TRL at 3 h preferentially increased the proportion of necrotic cells, whereas postprandial TRL at 5 h increased the proportion of apoptotic cells (P < 0.05). Cell cycle analysis showed that postprandial TRL blocked the human monocytes in S-phase. Our findings suggest that the level of TG and CHOL into postprandial TRL is associated with the ratios of oleic:palmitic acid and MUFA:SFA in dietary fats, which determines the ability of postprandial TRL to induce cytotoxicity and disturb the cell cycle in THP-1 cells.     

Differential effects of saturated and monounsaturated fatty acids on postprandial lipemia and incretin responses in healthy subjects.

BACKGROUND: Elevations of postprandial triacylglycerol-rich plasma lipoproteins and suppressions of HDL-cholesterol concentrations are considered potentially atherogenic. Long-term studies have shown beneficial effects of monounsaturated fatty acids (eg, oleic acid) on fasting lipid and lipoprotein concentrations in humans. A direct stimulatory effect of oleic acid on the secretion of glucagon-like peptide 1 (GLP-1) was shown in animal studies. OBJECTIVE: We compared the postprandial responses of glucose, insulin, fatty acids, triacylglycerol, gastric inhibitory polypeptide (GIP), and GLP-1 to test meals rich in saturated and monounsaturated fatty acids. DESIGN: Ten young, lean, healthy persons ingested 3 meals: an energy-free soup consumed with 50 g carbohydrate (control meal), the control meal plus 100 g butter, and the control meal plus 80 g olive oil. Triacylglycerol and retinyl palmitate responses were measured in total plasma, in a chylomicron-rich fraction, and in a chylomicron-poor fraction. RESULTS: No significant differences in glucose, insulin, or fatty acid responses to the 2 fat-rich meals were seen. Plasma triacylglycerol responses were highest after the butter meal, with chylomicron triacylglycerol rising 2.5-5-fold. Retinyl palmitate responses were higher and more prolonged after the butter meal than after the control and olive oil meals, whereas both postprandial HDL-cholesterol concentrations and GLP-1 and GIP responses were higher after the olive oil meal than after the butter meal. CONCLUSIONS: Olive oil induced lower triacylglycerol concentrations and higher HDL-cholesterol concentrations than butter, without eliciting differences in concentrations of glucose, insulin, or fatty acids. Furthermore, olive oil induced higher concentrations of GLP-1 and GIP than did butter, which may point to a relation between fatty acid composition, incretin responses, and triacylglycerol metabolism in the postprandial phase.     

Postprandial serum triacylglycerols and oxidative stress in mice after consumption of fish oil, soy oil or olive oil: possible role for paraoxonase-1 triacylglycerol lipase-like activity

OBJECTIVE: Postprandial triacylglycerols and oxidative stress responses are influenced by the type of fat consumed. We investigated the effect of individual unsaturated fatty acids or oils (fish, soy, or olive) on postprandial triglyceridemia response in association with serum resistance to oxidation and paraoxonase-1 (PON1) activity. METHODS: Balb/C mice were supplemented with phosphate buffered saline (control), docosahexaenoic acid (omega-3), linoleic acid (omega-6), or oleic acid (omega-9; 500 mug/300 muL of phosphate buffered saline) and with fish, soy, or olive oil (300 muL); blood samples were collected 2 h after feeding. RESULTS: Serum triacylglycerol and oxidative stress responses increased after intake of all unsaturated fatty acids and oil supplements. However, ingestion of fish oil or its major fatty acid, docosahexaenoic acid, induced the most remarkable increase in postprandial serum triacylglycerols and in the susceptibility of serum to in vitro oxidation. Serum PON1 activity was decreased by 24% after fish oil ingestion. The increase in postprandial serum susceptibility to oxidation was lower after soy oil supplementation to PON1-transgenic mice in comparison with Balb/C mice, showing that PON1 attenuates the postprandial serum oxidative response. In parallel, in PON1-transgenic mice, a decreased postprandial triacylglycerol response was noted, suggesting PON1 involvement in triacylglycerol metabolism. PON1 exhibited a triacylglycerol lipase-like activity on chylomicrons. CONCLUSION: PON1 attenuates the postprandial oxidative stress response, and this could have resulted from PON1 lipase-like activity on chylomicron triacylglycerols.     

Butter differs from olive oil and sunflower oil in its effects on postprandial lipemia and triacylglycerol-rich lipoproteins after single mixed meals in healthy young men

Accumulation of postprandial triacylglycerol-rich lipoproteins is generated by assimilation of ingested dietary fat and has been increasingly related to atherogenic risk. Nevertheless, the influence of different kinds of dietary fatty acids on postprandial lipid metabolism is not well established, except for (n-3) polyunsaturated long-chain fatty acids. Our goal was to evaluate the effects of test meals containing a common edible fat source of saturated (butter), monounsaturated (olive oil) or (n-6) polyunsaturated (sunflower oil) fatty acids on postprandial lipid and triacylglycerol-rich lipoprotein responses. After a 12-h fast, 10 healthy young men ingested mixed meals containing 0 g (control) or 40 g fat, provided as butter, olive oil or sunflower oil in a random order. Fasting and postmeal blood samples were collected for 7 h. The no-fat test meal did not elicit any change over baseline except for plasma phospholipids, insulin and nonesterified fatty acids. Conversely, the three fat-containing meals elicited bell-shaped postprandial changes (P < 0.05) in serum triacylglycerols, free and esterified cholesterol, and nonesterified fatty acids. The butter meal induced a lower postprandial rise of triacylglycerols in serum and chylomicrons (incremental AUC, mmol.h/L: 0.72) than the two unsaturated oils (olive oil: 1.6, sunflower oil: 1.8), which did not differ. Circulating chylomicrons were smaller after the butter meal than after the two vegetable oil meals. The in vitro susceptibility of circulating chylomicrons to hydrolysis by postheparin plasma was higher after sunflower oil than after butter or olive oil. We conclude that butter results in lower postprandial lipemia and chylomicron accumulation in the circulation of young men than olive or sunflower oils after consumption of a single mixed meal.     

The unsaponifiable fraction of virgin olive oil in chylomicrons from men improves the balance between vasoprotective and prothrombotic factors released by endothelial cells

Minor components of virgin olive oil (VOO) may play a key role in the beneficial effects of VOO on atherosclerosis. In the present study we evaluated the influence of the unsaponifiable fraction of VOO on the production of eicosanoids and nitric oxide (NO) by endothelial cells (HUVECs). Triglyceride-rich lipoprotein (TRLs) were isolated from human serum after the intake of meals enriched in 3 high-oleic acid oils, i.e., high-oleic sunflower (HOSO), VOO, or enriched-virgin olive (EVO) oils, the last-mentioned containing 2.4% of unsaponifiable matter. HOSO induced a greater accumulation of triglycerides (TGs) in the postprandial serum than VOO or EVO, as measured by calculating the area under the curve. The incubation with TRLs increased NO release by endothelial cells compared with untreated control cells, but the effects of the various TRLs did not differ. EVO-derived TRLs reduced the production of prostaglandin E(2) (PGE(2)) and thromboxane B(2) (TxB(2)) (the stable metabolite of TxA(2)) compared with VOO- or HOSO-derived TRLs. The release of PGI(2) (as 6-keto PGF(1alpha)) was similarly diminished by all TRLs compared with the control. In conclusion, the unsaponifiable fraction of VOO does not affect postprandial triglyceridemia, but it has favorable effects on endothelial function, mainly by reducing proinflammatory and vasoconstrictor eicosanoid synthesis (PGE(2) and TxB(2)).     

Differential effects of saturated and monounsaturated fats on postprandial lipemia and glucagon-like peptide 1 responses in patients with type 2 diabetes

BACKGROUND: Postprandial lipemia is important in the development of coronary artery disease because of elevated postprandial triacylglycerol-rich plasma lipoproteins and suppressed HDL-cholesterol concentrations. We showed in healthy subjects a possible association between postprandial lipid metabolism and the responses of the duodenal incretin hormones glucagon-like peptide 1 (GLP-1) and gastric inhibitory polypeptide after meals rich in saturated and monounsaturated fatty acids (oleic acid), respectively. OBJECTIVE: The objective was to compare the postprandial responses (8 h) of glucose, insulin, fatty acids, triacylglycerol, gastric inhibitory polypeptide, and GLP-1 to saturated- and monounsaturated-rich test meals. DESIGN: Twelve overweight patients with type 2 diabetes ingested 3 meals randomly: an energy-free soup with 50 g carbohydrate (control meal), the control meal plus 100 g butter, and the control meal plus 80 g olive oil. Triacylglycerol responses were measured in total plasma and in a chylomicron-rich and a chylomicron-poor fraction. RESULTS: No significant differences in the glucose, insulin, or fatty acid responses to the 2 fat-rich meals were seen. The plasma triacylglycerol and chylomicron triacylglycerol responses were highest after the butter meal. HDL-cholesterol concentrations decreased significantly after the butter meal but did not change significantly after the olive oil meal. GLP-1 responses were highest after the olive oil meal. CONCLUSIONS: Olive oil induced lower triacylglycerol concentrations and higher HDL-cholesterol concentrations than did butter, without eliciting significant changes in glucose, insulin, or fatty acids. Furthermore, olive oil induced higher concentrations of GLP-1, which may indicate a relation between fatty acid composition, incretin responses, and triacylglycerol metabolism postprandially in patients with type 2 diabetes.     

No effects of olive oils with different phenolic content compared to corn oil on 1,2-dimethylhydrazine-induced colon carcinogenesis in rats

BACKGROUND: Some epidemiological and experimental studies suggest that olive oil, despite its elevated caloric content, may have protective activity against colon cancer, partially due to its phenolic content. However, little experimental evidence exists to support this claim in vivo. AIM OF THE STUDY: To test the effect of olive oils with different phenolic content in a well-characterized model of colon carcinogenesis, comparing them with corn oil (CO). METHODS: F344 rats were fed AIN-76 based diets for the entire experimental period; the diets contained 23% (w/w) of lipids from three different sources: extra-virgin olive oil rich in phenolic compounds (EV), rectified olive oil (ROO) with the same fatty acid composition but devoid of phenolic compounds and CO as a control diet. One week later, rats were induced with 1,2-dimethylhydrazine (DMH) (150 mg/kg b.w. x 2 times) to measure preneoplastic lesions (aberrant crypt foci (ACF) and mucin depleted foci (MDF)) and tumours in the intestine. RESULTS: Thirteen weeks after DMH, the numbers of ACF and MDF were similar in the different groups (ACF/colon were 344.9 +/- 27.0, 288.6 +/- 28.5 and 289.8 +/- 21.4 in CO, EV and ROO groups, respectively, means +/- SE; MDF/colon were 8.83 +/- 1.2, 8.41 +/- 1.5 and 8.75 +/- 1.6 in CO, EV and ROO groups, respectively, means +/- SE). Thirty-two weeks after DMH, the incidence of tumours (rats with tumours/rats in the group) did not differ among the different groups (20/21, 18/19 and 20/20 in the CO, EV, and ROO groups, respectively). Similarly, the number of tumours/ rat in the colorectum (both adenomas and cancers) was not different in the three different groups (2.33 +/- 0.26, 2.42 +/- 0.41 and 2.25 +/- 0.40 in CO, EV and ROO groups, respectively, means +/- SE). CONCLUSIONS: Olive oil, irrespective of its phenolic content, does not affect DMH-induced colon carcinogenesis in F344 rats compared with CO.     

Ratio of oleic to palmitic acid is a dietary determinant of thrombogenic and fibrinolytic factors during the postprandial state in men

BACKGROUND: The nature of dietary fats affects the postprandial activation of the hemostatic system. OBJECTIVE: We investigated whether the ratio of oleic to palmitic acid [and that of monounsaturated to saturated fatty acids (MUFA:SFA)] in the diet affects postprandial concentrations of triacylglycerols, tissue factor (TF), fibrinogen, tissue-type plasminogen activator (t-PA), and plasminogen activator inhibitor 1 (PAI-1). DESIGN: We studied the effects of diets enriched in olive oil (ROO), high-palmitic sunflower oil (HPSO), butter, or a mixture of vegetable and fish oils (VEFO) on circulating concentrations of the aforementioned factors in 14 healthy men. The fats had ratios of oleic to palmitic acid (MUFA:SFA) of 6.83 (5.43), 2.36 (2.42), 0.82 (0.48), and 13.81 (7.08). RESULTS: The largest and longest-lasting postprandial changes in plasma triacylglycerol concentrations were found with the butter-based diet (all P < 0.05). No correlation was observed between the net incremental area under the curve (netAUC) for triacylglycerol and the ratio of oleic to palmitic acid (or MUFA:SFA) in the dietary fats. The netAUCs for TF and PAI-1, however, were inversely related to the ratio of oleic to palmitic acid (and MUFA:SFA) in ROO, HPSO, butter, and VEFO. Similar results were found for the fibrinogen netAUC when VEFO was omitted from the analysis. The netAUC for t-PA was inversely correlated with postprandial concentrations of triacylglycerol. CONCLUSIONS: Postprandial concentrations of TF, fibrinogen, and PAI-1 are associated with the ratio of oleic to palmitic acid (MUFA:SFA) in dietary fats. The postprandial t-PA response is related to postprandial concentrations of triacylglycerol.     

Hypocholesterolemic effect of triterpene alcohols with soysterol on plasma cholesterol in rats

To identify the synergistic hypocholesterolemic substance found in soybean oil unsaponifiable matter, rats were fed diets containing various fractions of the unsaponifiable matter prepared by silicic acid column chromatography. The plasma cholesterol level of the group fed the alcohol fraction, which mainly consisted of triterpene alcohols, was significantly lower and the effect was synergistic with soysterol. So the effect of cycloartenol and 24-methylenecycloartanol, which are main constituents of triterpene alcohols in soybean oil unsaponifiable matter, was investigated. Both compounds were prepared from gamma-oryzanol (ferulate) and were added (0.05%) respectively to the experimental diet containing 0.5% cholesterol and 1% soysterol. It was observed that both cycloartenol and 24-methylenecycloartanol in combination with soysterol greatly reduced the plasma cholesterol and enhanced cholesterol excretion. This suggests that the hypocholesterolemic activity of dietary vegetable oils may account for not only their fatty acid compositions and sterol contents but also the synergistic hypocholesterolemic effect of triterpene alcohols.     

Olive oil increases the number of triacylglycerol-rich chylomicron particles compared with other oils: an effect retained when a second standard meal is fed

BACKGROUND: Compared with the postprandial events after a single meal, different events occur when a second meal is ingested 4-6 h after a first meal. There is a rapid appearance of chylomicrons in the circulation carrying fat ingested with the first meal, with a peak 1 h after the second meal. OBJECTIVE: Our goal was to examine whether different dietary oils have effects on the storage of triacylglycerol as a result of differences in their digestion, absorption, and incorporation into chylomicrons. DESIGN: A single-blind, randomized, within-subject crossover design was used to study the effects of palm oil, safflower oil, a mixture of fish and safflower oil, and olive oil on postprandial apolipoprotein (apo) B-48, retinyl ester, and triacylglycerol in the S(f) > 400 fraction with the use of a sequential meal protocol. RESULTS: For triacylglycerol, retinyl ester, and apo B-48, the time to reach peak concentration was significantly earlier after the second meal than after the first meal (P < 0.005). This was apparent with each of the dietary oils. The pattern of the apo B-48 response differed significantly among the dietary oils, with olive oil resulting in higher concentrations after both meals (P = 0.003). The ratio of triacylglycerol to apo B-48 was significantly lower after olive oil feeding than after feeding with the other oils (P = 0.02). CONCLUSIONS: The rapid entry of chylomicrons after the ingestion of a second meal 5 h after a first meal was seen with all of the oils investigated. The short-term ingestion of olive oil produced more chylomicrons than did the other dietary oils, which may have been due to differences in the metabolic handling of olive oil within the gut.     

Differential modulation of hepatic very low-density lipoprotein secretion by triacylglycerol-rich lipoproteins derived from different oleic-acid rich dietary oils

Minor components from dietary oils can modulate the atherogenic response of the TAG-rich lipoproteins (TRL) in which they are transported. In the present study we investigated the influence of TRL isolated from man after the intake of oleic acid-rich oils with different minor component compositions on VLDL secretion by rat primary hepatocytes. TRL were isolated from nine men after the intake of meals enriched with high-oleic sunflower oil (HOSO) or virgin olive oil (VOO) or VOO enriched with minor components (EVO). TRL were incubated with rat primary hepatocytes and the lipid accumulation was analysed in the cells and the secreted VLDL. The expression of genes for proteins related to hepatic lipid metabolism and VLDL production was also measured. Incubation of hepatocytes with TRL derived from HOSO as compared to VOO led to lower intracellular lipid accumulation and VLDL production despite higher mRNA expression for diacylglycerol-acyltransferase, microsomal TAG transfer protein, apoB and PPARalpha. When TRL derived from EVO were used there were no changes in VLDL secretion. These results suggest that incorporation of minor components from dietary high-oleic oils into TRL modulates the effect of these atherogenic particles on VLDL secretion.     

Anti-inflammatory effect of virgin olive oil in stable coronary disease patients: a randomized, crossover, controlled trial

OBJECTIVES: To assess the effect of two similar olive oils, but with differences in their phenolic compounds (powerful antioxidant compounds), on inflammatory markers in stable coronary heart disease patients. DESIGN: Placebo-controlled, crossover, randomized trial. SETTING: Cardiology Department of Hospital del Mar and Institut Municipal d'Investigació Mèdica (Barcelona). SUBJECTS: Twenty-eight stable coronary heart disease patients. INTERVENTIONS: A raw daily dose of 50 ml of virgin and refined olive oil (ROO) was sequentially administered over two periods of 3-weeks, preceded by 2-week washout periods in which ROO was used.Results:Interleukin-6 (P<0.002) and C-reactive protein (P=0.024) decreased after virgin olive oil intervention. No changes were observed in soluble intercellular and vascular adhesion molecules, glucose and lipid profile. CONCLUSIONS: Consumption of virgin olive oil, could provide beneficial effects in stable coronary heart disease patients as an additional intervention to the pharmacological treatment.     

Greater enrichment of triacylglycerol-rich lipoproteins with apolipoproteins E and C-III after meals rich in saturated fatty acids than after meals rich in unsaturated fatty acids

BACKGROUND: Although there is considerable interest in the postprandial events involved in the absorption of dietary fats and the subsequent metabolism of diet-derived triacylglycerol-rich lipoproteins, little is known about the effects of meal fatty acids on the composition of these particles. OBJECTIVE: We examined the effect of meal fatty acids on the lipid and apolipoprotein contents of triacylglycerol-rich lipoproteins. DESIGN: Ten normolipidemic men received in random order a mixed meal containing 50 g of a mixture of palm oil and cocoa butter [rich in saturated fatty acids (SFAs)], safflower oil [n-6 polyunsaturated fatty acids (PUFAs)], or olive oil [monounsaturated fatty acids (MUFAs)] on 3 occasions. Fasting and postprandial apolipoproteins B-48, B-100, E, C-II, and C-III and lipids (triacylglycerol and cholesterol) were measured in plasma fractions with Svedberg flotation rates (S(f)) >400, S(f) 60-400, and S(f) 20-60. RESULTS: Calculation of the composition of the triacylglycerol-rich lipoproteins (expressed per mole of apolipoprotein B) showed notable differences in the lipid and apolipoprotein contents of the SFA-enriched particles in the S(f) > 400 and S(f) 60-400 fractions. After the SFA meal, triacylglycerol-rich lipoproteins in these fractions showed significantly greater amounts of triacylglycerol and of apolipoproteins C-II (S(f) 60-400 fraction only), C-III, and E than were found after the MUFA meal (P < 0.02) and more cholesterol, apolipoprotein C-III (S(f) > 400 fraction only), and apolipoprotein E than after the PUFA meal (P < 0.02). CONCLUSIONS: Differences in the composition of S(f) > 400 and S(f) 60-400 triacylglycerol-rich lipoproteins formed after saturated compared with unsaturated fatty acid-rich meals may explain differences in the metabolic handling of dietary fats.