Effect of thioacetamide and dexamethasone on serum lipids in rats fed on high-fat sunflower or olive oil diets.

We have previously reported that high-fat diets develop hepatic steatosis and, depending on the fat quality, affect serum lipid levels differently (J Nutr Sci Vitaminol, 1997, 43, 155-160). The aim of this work is to study the influence of high-fat diets (14% sunflower or olive oils) on serum lipids in a model of hepatic acute damage induced by thioacetamide, and their influence when dexamethasone is administered before thioacetamide injection. Serum lipids and hepatic collagen have been evaluated using biochemical methods, and the steatotic process by histological staining. The results showed that hepatic steatosis and fibrosis are developed either by high-fat diets or thioacetamide injection. Pretreatment with dexamethasone did not decrease the hepatic collagen content. Thioacetamide injection alone or pretreatment with dexamethasone produced increase in serum tryglicerides (TG), total cholesterol (TC) and LDL-C in both high-fat diet groups, and a HDL-C increase in the olive-oil group, even though the atherogenic indices (HDL/TC and HDL/TG) were different depending on the enriched diet. The administration of high-fat diets to study the influence of the fat quality on health and disease should be interpreted carefully due to the ability of the diets themselves to cause hepatic damage.     

Impact of diets containing corn oil or olive/sunflower oil mixture on the human plasma and lipoprotein lipid metabolism

Summary Background The effects of monounsaturated fatty acids (MUFA) rich diets compared to those that are rich in polyunsaturated fatty acids (PUFA) as well as the effects of an intake of single oils compared to oil mixtures are controversially discussed and results are contradictory. Aim of this study To evaluate the effects of a plant oil-mixture (olive/sunflower oil; saturated/monounsaturated/polyunsaturated (S/M/P) = 14:69:17) high in oleic acid but also showing a moderate content of polyunsaturated fatty acids (PUFA) in comparison with a single, PUFA rich corn oil (S/M/P = 13:33:54) used in a normal, balanced diet on human plasma and lipoprotein metabolism. Methods The double-blind designed study comprised 28 healthy, non-smoking young men aged between 19 and 31 years. After two weeks of adjustment (mixed, balanced diet: 11.6 MJ average, average fat intake ∼105 g/d), the design included a two week test period in which a diet with 80 g corn oil/d vs a mixture of 68 g olive- and 12 g sunflower oil/d (total 80 g) as the main fat source was given, followed by a crossover after two weeks. Compliance and ingestion of diets were monitored by assessing the fatty acid pattern in LDL and by determination of α- and γ-tocopherol in plasma and LDL. Results Diets were well incorporated due to the significant changes in plasma- and LDL-tocopherol levels and the significant different average ratio of oleic acid to linoleic acid in LDL. The PUFA-rich corn oil diet was able to reduce low density lipoprotein (LDL) cholesterol from adjustment to T2 significantly (p < 0.01), which was also confirmed by a trend after cross over (p=0.15). Total cholesterol (only after cross over at T3), total triglycerides (TG) and very low density lipoprotein (VLDL)-TG were significantly lower at T2 after the corn oil diet than after the mixed oil diet. Total high density lipoproteins (HDL) and HDL cholesterol remained unchanged by both diets. Conclusions The results show that during the intervention of two weeks for each diet and the following cross over the corn oil diet had more influence on lipoprotein metabolism than the MUFA-rich diet. The hypocholesteremic effect of the PUFA-rich diet must also be connected with the high amount of unsaponifiable substances, mainly phytosterols in the corn oil. Received: 10 May 2001, Accepted: 17 September 2001     

Different effects of diets rich in olive oil,rapeseed oil and sunflower-seed oil on postprandial lipid and lipoprotein concentrations and on lipoprotein oxidation susceptibility

Elevated concentrations of fasting and non-fasting triacylglycerol-rich lipoproteins (TRL) as well as oxidative changes of lipoproteins may increase the risk of ischaemic heart disease. To compare the effects of different diets rich in unsaturated fatty acids on the concentrations and in vitro oxidation of fasting and postprandial lipoproteins eighteen males consumed diets enriched with rapeseed oil (RO), olive oil (OO), or sunflower-seed oil (SO) in randomised order for periods of 3 weeks followed by a RO test meal. In the postprandial state the concentrations of cholesterol and triacylglycerol (TAG) in TRL were higher after consumption of OO compared with RO and SO (P<0.04), possibly related to differences in the fasting state. The propagation rates for VLDL and LDL oxidation were higher in the postprandial compared with the fasting state irrespective of diet. In the fasting state, the propagation rates were highest after SO (P<0.001), and in the postprandial state, SO gave rise to a shorter VLDL lag time (P=0.03) and a higher propagation rate than OO consumption (P=0.04). Overall, the SO diet resulted in a higher postprandial propagation rate of LDL (P<0.001) compared with RO and OO, while there was no effect of diet on LDL oxidation lag time. Our results suggest that RO and SO diets lower the postprandial cholesterol and TAG concentrations compared with OO, while RO and OO diets result in similar and lower in vitro susceptibility to oxidation of lipoproteins than SO.     

Effect of olive cultivar on bioaccessibility and antioxidant activity of phenolic fraction of virgin olive oil

Aim

This study aims to characterize the phenolic profile and antioxidant capacity of seven monovarietal virgin olive oils (VOOs) and evaluate their in vitro gastrointestinal stability.

Methods

‘Picual’, ‘Blanqueta’, ‘Sevillana’, ‘Habichuelero’, and ‘Chetoui’ olive cultivars were selected for VOO extraction. The oils were subjected to in vitro digestion. The recovery index (RI) of phenolic compounds after each digestion step and the bioaccessibility index (BI) were evaluated. In addition, the antioxidant activity of the bioaccessible fraction (BF) of VOOs was determined by DPPH, ABTS, and ORAC assays, as well as by studying the intracellular reactive oxygen species in Caco-2 cells.

Results

Differences were found in the composition of phenolic compounds in VOOs depending on cultivars. During the digestive process, important losses of phenolic compounds were observed between the buccal and duodenal steps, unlike HTy and Ty, which presented increased recovery due to the hydrolysis of secoiridoid derivatives. Differences in the bioaccessibility of phenolic compounds were found between varieties of VOOs. ‘Sevillana’ VOO had the highest total bioaccessibility (36%), followed by the ‘Picual’ (19%), ‘Chetoui’ (17%), ‘Habichuelero’ (10%), and ‘Blanqueta’ (8%) varieties. The BF of all the varieties of VOO showed similar radical ABTS scavenging capacity, ‘Chetoui’, and ‘Blanqueta’-BF having the highest radical DPPH scavenging capacity, and ‘Habichuelero’ and ‘Picual’-BF showing protective effects against the peroxyl radical measured by ORAC_FL assay. All VOO-BFs presented decreases in ROS levels in Caco-2 cells.

Conclusions

Our results suggest differences in the bioaccessibility of phenolics from diverse VOO varieties, which could lead to different biological properties. Therefore, this study represents a first step toward the development of novel dietary strategies focusing on the phenolic supplementation of different VOOs to preserve human health.

     

Effect of the olive oil phenol hydroxytyrosol on human hepatoma HepG2 cells

BACKGROUND: Scientific evidence suggests that olive oil's beneficial effects are related to the high level of antioxidants, including phenolic compounds such as hydroxytyrosol. In vivo studies have shown that olive oil HTy is bioavailable and its biological activities, similar to those reported for other natural antioxidants such as quercetin, include prevention of LDL oxidation. Previous studies from our laboratory have shown that HTy and other phenolics in olive oil are absorbed and metabolized by cultured human hepatoma HepG2 cells where glucuronidated and methylated conjugates were the main derivatives formed, resembling the metabolic profile of olive oil phenols observed in human plasma and urine. AIM OF THE STUDY: The effect of olive oil phenol (HTy) on cell viability and redox status of cultured HepG2 cells, and the protective effect of HTy against an oxidative stress induced by tertbutylhydroperoxide (t-BOOH) were investigated. METHODS: Lactate dehydrogenase activity as marker for cell integrity, concentration of reduced glutathione (GSH), generation of reactive oxygen species (ROS) and activity of the antioxidant enzyme glutathione peroxidase (GPx) as markers of redox status and determination of malondialdehyde (MDA) as marker of lipid peroxidation were measured. RESULTS: No changes in cell integrity or intrinsic antioxidant status resulted from a direct treatment with 10-40 microM HTy. Pre-treatment of HepG2 with 10-40 microM HTy for 2 or 20 h completely prevented cell damage as well as the decrease of reduced glutathione and increase of malondialdehyde evoked by t-BOOH in HepG2 cells. Reactive oxygen species generation and the significant increase of glutathione peroxidase activity induced by t-BOOH were greatly reduced when cells were pretreated with HTy. CONCLUSION: The results clearly show that treatment of HepG2 cells with the olive oil phenolic HTy may positively affect their antioxidant defense system, favoring cell integrity and resistance to cope with a stressful situation.     

Nabali olive oil ripening and oil properties

The effect of ripening of "Nabali" olives on the yield and some properties of the extracted oil was examined. Seven samples were harvested every 2 weeks and analyzed for moisture and oil content. The extracted oil was subjected to chemical analysis. Oil content increased and there were some significant changes in the proportions of fatty acids. Nabali olive oil is relatively high in arachidic, stearic and linoleic acids.     

Effect of ingestion of virgin olive oil on human low-density lipoprotein composition

OBJECTIVE: To measure the incorporation of oleic acid and antioxidants (phenols and vitamin E) to low density lipoprotein (LDL) after acute and short-term ingestion of virgin olive oil. To study whether this incorporation contributes to an increase in LDL resistance to oxidation. SETTING: Department of Food and Nutrition, University of Barcelona, Spain and Department of Lipids and Cardiovascular Epidemiology, IMIM, Barcelona, Spain. SUBJECTS: Sixteen healthy volunteers aged 25-65 y. DESIGN AND INTERVENTIONS: To observe the change in the fatty acid profile, vitamin E, phenolic compounds and LDL oxidation-related variables after the postprandial phase and after daily ingestion of olive oil for one week. RESULTS: Few changes were observed in the postprandial phase. However, after a week of olive oil consumption there was an increase in oleic acid (P=0.015), vitamin E (P=0.047), phenolics (P=0.021) and lag time (P=0.000), and a decrease in the maximum amount of dienes (P=0.045) and oxidation rate (P=0.05). CONCLUSION: After ingestion of virgin olive oil, an increase in antioxidants and oleic acid in LDL was observed as well as an improvement of LDL resistance to oxidation. Our results support the idea that daily ingestion of virgin olive oil could protect LDL from oxidation. SPONSORSHIP: This study was supported by a research grant from Spain (ALI 97-1607-C02-02).     

Impact of diets with corn oil or olive/sunflower oils on DNA damage in healthy young men

BACKGROUND: Plant fats and oils are major sources of mono- and polyunsaturated fatty acids as well as vitamin E, the major fat-soluble antioxidants in human nutrition. Dietary antioxidants are expected to reduce cancer risk by minimizing DNA damage. AIM OF THE STUDY: To compare the effects of gamma-tocopherol rich corn oil and the mixture of the alpha-tocopherol rich olive/sunflower oil on plasma concentration of tocopherols and on the frequency of sister chromatid exchange (SCE), an indicator of DNA damage. METHODS: This study had a double-blind, cross-over design and was conducted in 20 normal healthy non-smoking males aged 19-31 years. Design included a 2-week adjustment period and two 2-week test periods in which diets containing 30% energy as fat including either 80 g of corn oil (CO) (20 mg alpha-tocopherol, 100 mg gamma-tocopherol) or 80 g of olive/ sunflower oil (OSO) (24 mg alpha-tocopherol, 2.4 mg gamma-tocopherol), as the main fat-source, were given. Blood samples for analysis of SCE rate and content of tocopherols were collected at the beginning (T0), after adjustment (T1) and after the test period (T2) in intervals of 2 weeks. RESULTS: After two weeks of the corn oil diet, the plasma concentration of gamma-tocopherol increased but alpha-tocopherol decreased significantly compared to the olive/sunflower oil diet. The concentration of alpha-tocopherol increased (CO: 22.99 +/- 1.11 vs. OSO: 24.40 +/- 1.49 micromol/l) and that of gamma-tocopherol decreased (CO: 4.19 +/- 0.29 vs. OSO: 2.99 +/- 0.25 micromol/l) after the olive/sunflower oil diet. Intake of the corn oil diet was associated with reduced SCE rate and intensity, whereas there was no change in SCE after the olive/sunflower oil diet (CO: 7.66 +/- 0.25 vs. OSO: 8.06 +/- 0.47 mean SCE/cell) CONCLUSIONS: The combination of gamma-tocopherol with alpha-tocopherol in corn oil diet despite the lower alpha-tocopherol equivalents/diene acid equivalents ratio achieved better protection against DNA damage than alpha-tocopherol alone in the olive/sunflower oil diet.     

橄榄油对大鼠去势后骨代谢指标及骨密度的影响

目的:观察橄榄油对去势后大鼠骨代谢和骨密度的影响,探讨并分析橄榄油防治绝经后骨质疏松症(PMOP)的有效性及机理。方法:将30只5～6个月龄清洁型SD雌性大鼠进行随机分成四组:①假手术组(Sham组)、②去卵巢组(OVX组)、③去卵巢+橄榄油组(OVX+Olive)、④去卵巢+雌激素组(OVX+E)。治疗组用药:(OVX+Olive)组及(OVX+E)组均采用经口灌胃方式进行用药,按1 ml/100 g体重,1次/天灌胃,连续12周。12周后分别左心室取血,检测血中雌二醇(E2)、血钙、血碱性磷酸酶(ALP)、白介素-6(IL-6)水平,放血处死后取出腰椎及左侧股骨行双能X线骨密度(DEXA)测定。结果:OVX组中血E2明显低于Sham组和治疗组,差异有统计学意义(P<0.01、P<0.05),ALP、IL-6值显著高于其余三组,差异有统计学意义(P<0.05);治疗组中E2、ALP、IL-6与Sham组差异无统计学意义(P>0.05);四组中血钙值差异均无统计学意义(P>0.05)。去势橄榄油组与雌激素组骨密度平均值均较OVX组高,差异有统计学意义(P<0.05),但该两组间差异无统计学意义(P>0.05)。结论:橄榄油能有效地减轻大鼠卵巢切除术引起的骨质丢失,可能通过补充植物雌激素发挥拟雌激素样作用。     

Effect of dietary olive oil, corn oil and medium-chain triglycerides on the lipid composition of rat red blood cell membranes

The effects of dietary olive oil, corn oil and medium-chain triglycerides (MCT) on factors that characterized erythrocyte membrane lipid fluidity were studied. Weanling rats were fed for 3 or 5 wk high fat diets (10%) containing olive oil, corn oil or a mixture of MCT with olive oil or corn oil. Total phospholipids and phosphatidylcholine of erythrocyte ghosts obtained from olive oil-fed animals, as compared to those fed corn oil, showed an increase in long-chain polyunsaturated fatty acids (PUFA) of the (n-6) and (n-3) series and a decrease in saturated fatty acids. The addition of MCT to the olive oil diet induced an increase in palmitic, palmitoleic and delta-5,8,11-eicosatrienoic acids and a decrease in long-chain PUFA of the (n-6) series in erythrocyte membrane phospholipids. Conversely, rats fed a mixture of MCT and corn oil, as compared to those fed exclusively corn oil, showed increase in long-chain PUFA of the (n-6) and (n-3) series, with no changes in saturated fatty acid levels. The cholesterol/phosphorus molar ratio showed only a slight increase with MCT supplementation. Olive oil feeding induced important changes in fatty acid composition of erythrocyte membrane phospholipids as compared to corn oil feeding without modifying the cholesterol/phosphorus ratio and MCT feeding slightly affected red blood cell membrane lipid composition.     

Effect of barley supplementation on the fecal microbiota,caecal biochemistry,and key biomarkers of obesity and inflammation in obese db/db mice

European Journal of Nutrition - Barley is a low-glycemic index grain that can help diabetic and obese patients. The effect of barley intake depends on the host and the associated gut microbiota....     

Effect of olive oil phenolic compounds on the expression of blood pressure-related genes in healthy individuals

Purpose

To investigate whether the ingestion of olive oil having different phenolic contents influences the expression of blood pressure-related genes, involved in the renin–angiotensin–aldosterone system, in healthy humans.

Methods

A randomized, double-blind, crossover human trial with 18 healthy subjects, who ingested 25 mL/day of olive oils (1) high (366 mg/kg, HPC) and (2) low (2.7 mg/kg, LPC) in phenolic compounds for 3 weeks, preceded by 2-week washout periods. Determination of selected blood pressure-related gene expression in peripheral blood mononuclear cells (PBMNC) by qPCR, blood pressure and systemic biomarkers.

Results

HPC decreased systolic blood pressure compared to pre-intervention values and to LPC, and maintained diastolic blood pressure values compared to LPC. HPC decreased ACE and NR1H2 gene expressions compared with pre-intervention values, and IL8RA gene expression compared with LPC.

Conclusions

The introduction to the diet of an extra-virgin olive oil rich in phenolic compounds modulates the expression of some of the genes related to the renin–angiotensin–aldosterone system. These changes could underlie the decrease in systolic blood pressure observed.

     

Effect of phenol-rich extra virgin olive oil on markers of oxidation in healthy volunteers

OBJECTIVE: We studied whether consumption of phenol-rich extra virgin olive oil affects the susceptibility of low density lipoproteins (LDL) to oxidation and other markers of oxidation in humans. DESIGN: Randomized cross-over intervention trial, stratified according to sex, age and energy intake. SETTING: Division of Human Nutrition and Epidemiology, Wageningen University, The Netherlands. SUBJECTS: Forty-six healthy men and women completed the study. INTERVENTION: Subjects consumed two diets supplying 69 g per day of extra virgin olive oil either rich or poor in phenols for 3 weeks each. The mean difference in phenol intake between the treatments was 18 mg per day. Vitamin E intake was low during the whole study. Fasting blood samples were taken twice at the end of each period. RESULTS: Resistance of LDL and high density lipoprotein (HDL) to oxidation was not affected by treatment. The mean lag time of copper-induced formation of conjugated dienes was 1.6 min shorter in LDL and 0.4 min longer in HDL after the high phenol diet. Other markers of antioxidant capacity in plasma were also not affected: mean lipid hydroperoxides were 0.07 micromol/l higher, mean malondialdehydes were 0.001 micromol/l higher, mean protein carbonyls were 0.001 nmol/mg protein lower, and the mean ferric reducing ability of plasma (FRAP) was 0.006 mmol/l higher after the high phenol diet. All 95% confidence intervals enclosed zero. Serum cholesterol concentrations were not affected by the treatment. CONCLUSION: Consumption of 18 mg per day of phenols from extra virgin olive oil for 3 weeks did not affect LDL or HDL oxidation or other markers of antioxidant capacity in fasting plasma samples.     

Differential effect of high dietary iron on α-tocopherol and retinol levels in the liver and serum of mice fed olive oil– and corn oil–enriched diets

The influence of dietary fats on cellular α-tocopherol and retinol uptake in iron overload is poorly understood. The aim of this study was to investigate the effect of a high-iron diet on the retinol and α-tocopherol levels in mice fed olive oil– and corn oil–enriched diets. Mice were fed for 3 weeks a standard mouse chow (the control group) and diets enriched with 5% by weight of corn oil or olive oil. Diets of the mice fed corn oil and olive oil were additionally supplemented with 1% by weight carbonyl iron. Both dietary oils and iron increased the liver iron uptake. High-iron feeding induced oxidative stress in mice liver, measured as a thiobarbituric acid-reactive substance level. Both fats and iron induced changes in the liver fatty acid composition. Liver retinol and α-tocopherol stores increased with iron supplementation in the olive oil–enriched diet, with a simultaneous decrease in serum. The results suggest that the influx of α-tocopherol and retinol from serum to the liver is induced by high dietary iron. This redistribution appears to be stronger for retinol than for α-tocopherol and is also higher in mice fed olive oil than in mice fed corn oil, suggesting that the composition of dietary lipids is important in the treatment of high-iron tissue conditions. In conclusion, the results of this study suggest that the increase of hepatic α-tocopherol and retinol levels in the olive oil–based diet is a dietary-dependent responsive mechanism that probably is not primarily related to an increased risk of oxidative damage induced by high-iron intake.     

橄榄油和鱼油对大鼠血脂和脂质过氧化的影响

为观察橄榄油和鱼油对大鼠血脂水平及脂质过氧化的影响 ,将 44只Wistar大鼠随机分成 4组 ,分别接受正常饲料、高脂饲料、高脂饲料加橄榄油灌胃 (4ml·kg- 1 ·d- 1 )和高脂饲料加鱼油灌胃 (4ml·kg- 1 ·d- 1 )处理。实验期 6周。结果显示 ,橄榄油和鱼油均能降低大鼠血清总胆固醇和甘油三酯水平 ,并且鱼油的效果较橄榄油好 ,鱼油能够显著提高高密度脂蛋白胆固醇 ;橄榄油和鱼油均可降低高脂饲料引起的肝 体比值增大 ,而且鱼油可以明显减少肾脏和睾丸周围脂肪。橄榄油组和鱼油组大鼠的血清丙二醛水平均明显下降 ;而且红细胞超氧化物歧化酶活性有所提高 ,表明橄榄油和鱼油对进食高脂饲料引起的体内过氧化物水平升高具有拮抗作用。结果提示橄榄油和鱼油对高血胆固醇、甘油三酯有降低作用 ,并能改善高脂所致体内过氧化状态异常 ,减轻对机体的过氧化损伤 ,鱼油的效果优于橄榄油     

Antioxidant and anti-atherogenic activities of olive oil phenolics

The aim of the current study was to investigate the antioxidant and cellular activity of the olive oil phenolics oleuropein, tyrosol, hydroxytyrosol, and homovanillic alcohol (which is also a major metabolite of hydroxytyrosol). Well-characterized chemical and biochemical assays were used to assess the antioxidant potential of the compounds. Further experiments investigated their influence in cell culture on cytotoxic effects of hydrogen peroxide and oxidized low-density lipoprotein (LDL), nitric oxide production by activated macrophages, and secretion of chemoattractant and cell adhesion molecules by the endothelium. Inhibitory influences on in vitro platelet aggregation were also measured. The antioxidant assays indicated that homovanillic alcohol was a significantly more potent antioxidant than the other phenolics, both in chemical assays and in prolonging the lag phase of LDL oxidation. Cell culture experiments suggested that the olive oil phenolics induce a significant reduction in the secretion of intercellular adhesion molecule-1 and vascular cell adhesion molecule-1 (and a trend towards a reduced secretion of monocyte chemoattractant protein-1), and protect against cytotoxic effects of hydrogen peroxide and oxidized LDL. However, no influence on nitric oxide production or platelet aggregation was evident. The data show that olive oil phenolics have biochemical and cellular actions, which, if also apparent in vivo, could exert cardioprotective effects.     

Anticarcinogenic compounds of olive oil and related biomarkers

Olive oil, one of the oldest vegetable oils consumed without any refining, is associated with a reduced risk of a number of common cancers. Minor constituents of virgin olive oil have been suggested to be among the major chemopreventive components. A brief overview is presented of recent findings concerning the bioavailability of certain important olive oil minor components including efficient antioxidant polyphenols, the triterpene hydrocarbon squalene and β-sitosterol, considered as putative nutritional biomarkers, in relation to the incidence of cancer.