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PubMed2003

Study of the cultivar-composition relationship in Sicilian olive oils by GC, NMR, and statistical methods.

The aim of this research is to find if there is direct evidence relating the fatty acid composition of olive oils to specific cultivars grown within a well-limited geographical region. To group olive oils according to their own cultivars,(13)C high-field nuclear magnetic resonance (NMR) and gas chromatography (GC) were used to analyze 60 extra virgin olive oils from the same Italian region (southwestern Sicily) obtained from four monovarietal cultivars. The (13)C NMR spectrum provides information about glycerol triesters of olive oils, i.e., about the acyl composition of major components and about the fatty acids' positional distribution on the glycerol moiety. GC gives the complete fatty acid profile of olive oil samples. Selection of NMR and GC peaks on the basis of their sensitivity to the different cultivars was performed by using multivariate analysis of variance (MANOVA). Principal component analysis, tree clustering analysis, multidimensional scaling (MDS), and linear discriminant analysis (LDA) were then performed on the MANOVA-selected peaks. Results obtained from (13)C NMR and GC techniques combined with the multivariate statistical procedure are in good agreement and prove the usefulness of fatty acids analysis to group the monovarietal olive oils belonging to the same cultivars. Grouping of olive oils according to their cultivars occurs for particular (13)C resonances all belonging to fatty chains in the sn 1,3 position of the glycerol moiety.

Analysis of Variance↗
PubMed2006

Olive oil consumption and weight change: the SUN prospective cohort study.

The aim of this dynamic prospective follow-up study was to assess the association between olive oil consumption and the likelihood of weight gain or the incidence of overweight or obesity in a large Mediterranean cohort of 7,368 male and female Spanish university graduates (the SUN Project) who were followed for a median period of 28.5 mon. A validated Food Frequency Questionnaire was administered at baseline, and respondents also completed a follow-up questionnaire after 28.5 mon. Changes in participants' consumption of olive oil and their weight were assessed during follow-up. A higher baseline consumption of olive oil was associated with a lower likelihood of weight gain, although the differences were not statistically significant. The adjusted difference in weight gain (kg) was -0.16 [95% confidence interval (CI): -0.42 to +0.11] for participants in the upper quintile of olive oil consumption (median: 46 g/d) compared with those in the lowest quintile (median: 6 g/d). For participants with a high baseline consumption of olive oil whose olive oil consumption also increased during follow-up, we found a slightly increased but nonsignificant risk of incidence of overweight or obesity (adjusted odds ratio = 1.19, 95% CI: 0.73 to 1.95). Our study, carried out in a sample of free-living people, shows that a high amount of olive oil consumption is not associated with higher weight gain or a significantly higher risk of developing overweight or obesity in the context of the Mediterranean food pattern.

Adult↗
PubMedDate not supplied

Effect of minor components of virgin olive oil on topical antiinflammatory assays.

Interest in the health-promoting effects of virgin olive oil, an important part of the "Mediterranean diet", prompted us to determine the antiinflammatory effects of erythrodiol, beta-sitosterol and squalene, identified as major components of the so-called "unsaponifiable fraction" of virgin olive oil, as well as of the phenolic compounds from the "polar fraction": oleuropein, tyrosol, hydroxytyrosol and caffeic acid. Their activities were compared to those of both, total unsaponifiable and polar fractions. This study was designed to analyse the antiinflammatory effect of these specific compounds from virgin olive oil on edema in mice induced by either arachidonic acid (AA) or 12-O-tetradecanoylphorbol acetate (TPA). The inhibition of the myeloperoxidase (MPO), marker enzyme of the accumulation of neutrophils in the inflamed tissue, was also investigated by the TPA model. The topical application of the olive oil compounds (0.5 mg/ear) produced a variable degree of antiinflammatory effect with both assays. In the auricular edema induced by TPA, beta-sitosterol and erythrodiol from the unsaponifiable fraction of the oil showed a potent antiedematous effect with a 61.4% and 82.1% of inhibition respectively, values not very different to that of the reference indomethacin (85.6%) at 0.5 mg/ear. The four phenolics exerted a similar range of inhibition (33-45%). All compounds strongly inhibited the enzyme myeloperoxidase, indicating a reduction of the neutrophil influx in the inflamed tissues. The strongest inhibitor of AA edema was the total unsaponifiable fraction which inhibition was 34%, similar to that obtained by the reference drug dexamethasone at 0.05 mg/ear. Among the phenolics, oleuropein also produced an inhibition of about 30% with the same dose, but all the other components were found less active in this assay. The anti-inflammatory effects exerted by both unsaponifiable and polar compounds might contribute to the potential biological properties reported for virgin olive oil against different pathological processes.

Animals↗
PubMed2002

Risk of first non-fatal myocardial infarction negatively associated with olive oil consumption: a case-control study in Spain.

BACKGROUND: Olive oil is the main source of dietary lipids in most Mediterranean countries where mortality and incidence rates for coronary heart disease (CHD) are the lowest in Europe. Although international comparisons and mechanistic reasons support the hypothesis that a high olive oil intake may prevent CHD, limited data from studies of individuals are available. METHODS: A hospital-based case-control study was conducted in Pamplona (Spain) recruiting 171 patients (81% males, age <80 years) who suffered their first acute myocardial infarction and 171 age-, gender- and hospital-matched controls (admitted to minor surgery, trauma or urology wards). A validated semi-quantitative food frequency questionnaire (136 items) was used to appraise previous long-term dietary exposures. The same physician conducted the face-to-face interview for each case patient and his/her matched control. Conditional logistic regression modelling was used to take into account potential dietary and non-dietary confounders. RESULTS: The exposure to the upper quintile of energy-adjusted olive oil (median intake: 54 g/day) was associated with a statistically significant 82% relative reduction in the risk of a first myocardial infarction (OR = 0.18; 95% CI : 0.06-0.63) after adjustment for dietary and non-dietary confounders. CONCLUSIONS: Our data suggest that olive oil may reduce the risk of coronary disease. These findings require confirmation in further observational studies and trials.

Case-Control Studies↗
PubMed2004

Synergistic action of olive oil supplementation and dietary restriction on serum lipids and cardiac antioxidant defences.

Caloric intake is higher than recommended in many populations. Therefore, enhancing olive oil intake alone may not be the most effective way to prevent cardiovascular diseases. The purpose of the present study was to analyse the association of olive oil and dietary restriction on lipid profile and myocardial antioxidant defences. Male Wistar rats (180-200 g, n = 6) were divided into 4 groups: control ad libitum diet (C), 50% restricted diet (DR), fed ad libitum and supplemented with olive oil (3 mL/(kg x day)) (OO), and 50% restricted diet and supplemented with olive oil (DROO). After 30 days of treatments, OO, DR, and DROO groups had increased total cholesterol and high-density lipoprotein cholesterol concentrations. DR and DROO animals showed decreased low-density lipoprotein cholesterol. DROO had the lowest low-density lipoprotein cholesterol concentration. Total lipids and triacylglycerols were raised by dietary restriction and diminished by olive oil. OO rats had higher myocardial superoxide dismutase and lower catalase and glutathione peroxidase activities than C rats. DR and DROO showed enhanced cardiac superoxide dismutase, catalase, and glutathione peroxidase activities from the control. Olive oil supplementation alone improved the lipid profile but was more effective when coupled with dietary restriction. There was a synergistic beneficial action of dietary restriction and olive oil on serum lipids and myocardial antioxidant defences.

Animals↗
PubMed2002

Olive oil as a functional food: epidemiology and nutritional approaches.

Olive oil is an integral ingredient of the Mediterranean diet and accumulating evidence suggests that it may have health benefits that include reduction of risk factors of coronary heart disease, prevention of several varieties of cancers, and modification of immune and inflammatory responses. Olive oil appears to be an example of a functional food, with varied components that may contribute to its overall therapeutic characteristics. Olive oil is known for its high levels of monounsaturated fatty acids and is also a good source of phytochemicals including polyphenolic compounds, squalene, and alpha-tocopherol.

Cardiovascular Diseases↗
PubMedDate not supplied

Mediterranean diet and health: is all the secret in olive oil?

OBJECTIVE: The purpose of this study was to review and analyze the synergies of olive oil related food consumption and nutrient intake in a Mediterranean region. DESIGN: Cross sectional study by face to face interview. SETTING: Population based random sample derived from the Catalan Nutrition Survey. SUBJECTS: 1600 individuals between 18 and 60 years of age. INTERVENTION: Two 24-hour recalls were administered to measure food and nutrient intakes. Food group consumption and nutrient intakes ratios between the highest(greater than 13.5% of total calories, 4th quartile)and lowest quartiles (less than 6.8% of total calories,1st quartile) of olive oil consumption were calculated. RESULTS: Comparing the highest quartile of olive oil consumption to the lowest, the highest ratios by food group consumption were observed for eggs, vegetables and fish in both men and women and non fried potatoes in women only. Lower ratios were associated in both sexes with soft drinks, commercially baked goods, processed meat and full fat milk and nuts in women only, and fried potatoes in men only. Analysis by nutrients showed higher ratios for carotenoids,monounsaturated fatty acids, vitamin E and folic acid in both sexes and Vitamin C and polyunsaturated fatty acids in women only. Lower ratios were seen for mono,di and polysaccharides, saturated fat, retinol and sodium in both genders and calcium niacin, thiamin,riboflavin and fibre in men only. CONCLUSION: Olive oil is a key contributor to the healthy aspects attributed to the Mediterranean diet, since its own health attributes may be added to those of foods that it's commonly served with (fish, vegetables), thus contributing to its thrombosis related disease preventive properties. As such, nutritional objectives in Mediterranean countries should address reducing saturated fats, without modifying quantities of olive oil,and increasing fish, vegetables and nuts.

Adolescent↗
PubMed1995

[Thermogenesis and energy utilization of olive oil and fish oil in a model study with sows].

An animal model experiment was conducted with nine adult sows to study the effect of olive oil and fish oil (40% polyunsaturated fatty acids) on thermogenesis compared to wheat starch as control. The treatments were given to each animal according to a latin square design. The basal diet (20 g DM/kg W0.75) was mainly based on barley and soybean meal, and matched 60% of the ME requirements with all the other nutrients meeting maintenance requirements. The isoenergetic supplements amounted to 176 kJ gross energy per kg W0.75 and day. During each experimental period a complete energy balance was recorded for each animal using indirect calorimetry technique (RQ-method) as well as the carbon-nitrogen-balance technique. The treatments did not influence the digestibility of the rations. Digestibility of energy and of carbon averaged 83.4% and 83.3%, respectively. All three supplements were nearly completely digested as calculated by the difference method. Fish oil increased urine energy and decreased CH4 production, the shifts, however, were in absolute terms very small. The mean O2 consumption was 1,002 l/d showing no significant treatment effects. CO2 production was lowered with olive oil by 10%, and with fish oil by 13% compared to the starch diet. The daily heat production was 20.95, 20.72, and 20.04 MJ when starch, olive oil or fish oil was given. Corrected for equal energy retention the difference of thermogenesis between olive oil and starch was -0.4 MJ/d, and between fish oil and starch -1.2 MJ/d. These differences corresponded to a relation of starch:olive oil:fish oil = 1:0.95:0.86. The relation between starch and olive oil reflected exactly the theoretical expectation, calculated from the ATP regeneration by oxidation of both nutrients. When fish oil was added, the daily heat production was lower than theoretically calculated, which might be interpreted as an effect on the metabolic rate in general rather than especially on the efficiency of ATP formation from fish oil oxidation. In any case, there was no hint of a facultative thermogenesis induced by the oils.

Adenosine Triphosphate↗
PubMed2006

Effects of olive oil and tomato lycopene combination on serum lycopene, lipid profile, and lipid oxidation.

OBJECTIVE: We compared the effect of two diets (a diet high in olive oil and a diet high in carbohydrate and low in olive oil) with high lycopene content and other controlled carotenoids on serum lycopene, lipids, and in vitro oxidation. METHODS: This was a randomized crossover dietary intervention study carried out in Launceston, Tasmania, Australia in healthy free-living individuals. Twenty-one healthy subjects who were 22 to 70 y old were recruited by advertisements in newspapers and a university newsletter. A randomized dietary intervention was done with two diets of 10 d each. One diet was high in olive oil and the other was high in carbohydrate and low in olive oil; the two diets contained the same basic foods and a controlled carotenoid content high in lycopene. RESULTS: Significant increases (P<0.001) in serum lycopene concentration on both diets were to similar final concentrations. Higher serum high-density lipoprotein cholesterol (P<0.01), lower ratio of total cholesterol to high-density lipoprotein (P<0.01), and lower triacylglycerols (P<0.05) occurred after the olive oil diet compared with the high-carbohydrate, low-fat diet. There was no difference in total antioxidant status and susceptibility of serum lipids to oxidation. CONCLUSIONS: Serum lycopene level changes with dietary lycopene intake irrespective of the amount of fat intake. However, a diet high in olive oil and rich in lycopene may decrease the risk of coronary heart disease by improving the serum lipid profile compared with a high-carbohydrate, low-fat, lycopene-rich diet.

Adult↗
PubMed2006

Effect of dietary virgin olive oil on urinary excretion of etheno-DNA adducts.

A significant protective effect against cancer and coronary heart disease has been attributed to the Mediterranean diet, in which olive oil is the main source of fat. Dietary antioxidants, as phenolic compounds from virgin olive oil, are candidates for reducing cancer risk by minimizing oxidatively derived DNA damage. Etheno-DNA adducts are formed as a result of oxidative stress and lipid peroxidation. To evaluate whether phenol-rich virgin olive oil influences urinary excretion of the etheno-DNA adducts epsilonAde, epsilondA, and epsilondC as markers of oxidative stress, a randomized, double-blinded, crossover trial with three intervention periods was conducted in 28 healthy men. Each intervention was of 3 weeks' duration and separated by 2-week washout periods. Twenty-five milliliters of similar olive oils, but with differences in their phenolic content (from 2.7 to 366 mg/kg), were supplied to each subject per day. The urinary excretion of the DNA adducts was assayed by LC-MS/MS in samples before and after consumption of high phenolic content olive oil (virgin). The 24-h excretion rate did not differ significantly between baseline and after virgin olive oil consumption: epsilonAde, 105.5 +/- 40.8 vs 116.4 +/- 53.4 pmol epsilonAde/24 h (p = 0.21); epsilondA, 37.9 +/- 24.8 vs 37.6 17 +/- 24.2 pmol epsilondA/24 h (p = 0.93); and epsilondC, 218.7 +/- 157.2 vs 193.5 +/- 64.7 pmol epsilondC/24 h (p = 0.37). Multiple regression analysis showed a significant association between etheno-DNA adduct excretion rate and the dietary intake of linoleic acid (C18:2, omega-6) in healthy men. Consumption of 25 ml per day of phenol-rich virgin olive oil for 3 weeks did not modify to a significant degree the urinary excretion of etheno-DNA adducts in 28 healthy volunteers.

Adult↗
PubMedDate not supplied

[Coronary disease protective factors: antioxidant effect of olive oil].

Alongside the French paradox, the REGICOR Study (Girona, Spain) has shown another paradox in the Mediterranean area: a high prevalence of cardiovascular risk factors with low incidence of myocardial infarction in the population of Girona, Spain. The antioxidant effects associated with olive oil consumption could explain part of this 'Mediterranean Paradox'. Virgin olive oils processed by two centrifugation phases and with low fruit ripeness have the highest levels of antioxidant content. The total content of phenolic compounds (PC) from virgin olive oil could delay LDL oxidation. The content and nature of olive oil PC have a high influence in the antioxidant capacity of an olive oil. PC from diet could bind human LDL in non-supplemented volunteers. PC from virgin olive oil could bind LDL and tyrosol is bioavailable in humans from ingestion of virgin olive oil in its natural form.

Antioxidants↗
PubMed2003

Effects of dietary extra virgin olive oil on serum lipid resistance to oxidation and fatty acid composition in elderly lipidemic patients.

An inverse relation between high consumption of olive oil and low incidence of coronary heart disease among the people living in Mediterranean countries has been proposed. It has been shown, that an oleic acid-rich diet could increase the resistance of human LDL to in vitro oxidation which is postulated to play an important role in the development of atherosclerotic lesions. The aim of this study was to assess the effect of extra virgin olive oil consumptiom on the resistance of serum lipids to in vitro oxidation and on fatty acid composition in the serum of elderly lipidemic patients. A total of 26 patients (mean age 69 years) with combined hyperlipidemia consumed daily 2 table spoons (approx. 20 g) of extra virgin olive oil for 6 weeks. Plasma lipids, total antioxidant capacity, indices of serum lipid oxidizability (lag time and maximal rate of oxidation) and the content of fatty acids in serum phospholipids were determined before and after dietary supplementation with olive oil. Plasma total cholesterol and LDL cholesterol decreased significantly after 6 weeks of dietary intervention. A significant increase in the lag time of conjugated diene formation (p = 0.026) and the decrease in the rate of lipid oxidation (p = 0.030) were observed after olive oil consumption. The changes in the fatty acid profile were characterized by an increase in oleic acid content (p = 0.005) as well as by a decline in the content of linoleic acid (p = 0.020) and arachidonic acid (p = 0.022). Linear regression analysis revealed some interesting and significant correlations between indices of serum lipid resistance to oxidation and individual fatty acids, suggesting a protective effects of olive oil in lipoprotein oxidation. In conclusion, the daily consumption of extra virgin olive oil in elderly lipidemic patients favourably affected serum lipoprotein spectrum and fatty acid composition that probably contributed to the increased resistance of serum lipids to oxidation. (Tab. 2, Ref. 18).

Aged↗
PubMed2001

Effects of dietary virgin olive oil phenols on low density lipoprotein oxidation in hyperlipidemic patients.

The aim of this study was to assess the effects of the dietary intake of extra virgin olive oil on the oxidative susceptibility of low density lipoproteins (LDL) isolated from the plasma of hyperlipidemic patients. Ten patients with combined hyperlipidemia (mean plasma cholesterol 281 mg/dL, triglycerides 283 mg/dL) consumed a low-fat, low-cholesterol diet, with olive oil (20 g/d) as the only added fat, with no drug or vitamin supplementation for 6 wk. Then they were asked to replace the olive oil they usually consumed with extra virgin olive oil for 4 wk. LDL were isolated at the beginning, and after the 4 wk of dietary treatment. LDL susceptibility to CuSO4-mediated oxidation was evaluated by measuring the extent of lipid peroxidation. We also determined fatty acid composition and vitamin E in plasma and LDL and plasma phenolic content. Extra virgin olive oil intake did not affect fatty acid composition of LDL but significantly reduced the copper-induced formation of LDL hydroperoxides and lipoperoxidation end products as well as the depletion of LDL linoleic and arachidonic acid. A significant increase in the lag phase of conjugated diene formation was observed after dietary treatment. These differences are statistically correlated with the increase in plasma phenolic content observed at the end of the treatment with extra virgin olive oil; they are not correlated with LDL fatty acid composition or vitamin E content, which both remained unmodified after the added fat change. This report suggests that the daily intake of extra virgin olive oil in hyperlipidemic patients could reduce the susceptibility of LDL to oxidation, not only because of its high monounsaturated fatty acid content but probably also because of the antioxidative activity of its phenolic compounds.

Adult↗
PubMed2004

Dietary virgin olive oil enhances secretagogue-evoked calcium signaling in rat pancreatic acinar cells.

OBJECTIVE: We evaluated the long-term effects of a fat-enriched diet (virgin olive oil) on calcium mobilization and amylase secretion induced by cholecystokinin-octapeptide (CCK-8) in rat pancreatic acinar cells. Olive oil is a major component of the Mediterranean diet, and its role in human health is actively being debated. METHODS: Weaning male Wistar rats (21 d old) were assigned to one of two experimental groups and fed for 8 wk with a commercial chow (control group) or an experimental diet (olive group) containing 100 g/kg of virgin olive oil as dietary fat. Intracellular free calcium [Ca(2+)](i) levels were determined by loading the pancreatic cells with the fluorescent ratio-metric calcium indicator Fura-2 on an inverted fluorescent microscope. For measurement of amylase secretion, cells were incubated with the appropriate secretagogue for 30 min, and amylase activities in the supernatant were determined by the Phadebas blue starch method. Analysis of variance was used to test differences between groups. RESULTS: Compared with the control group, the CCK-8-induced increase in [Ca(2+)](i) occurred in cells from rats in the olive group (P < 0.05). This stimulatory effect of dietary virgin olive oil was observed in calcium oscillations and large [Ca(2+)](i) transients induced by low (20 pM/L) and high (10 nM/L) concentrations of CCK-8, respectively. In addition to the effects of dietary virgin olive oil on calcium mobilization, it increased (P < 0.05) amylase secretion in response to CCK-8. Olive oil treatment did not significantly alter resting [Ca(2+)](i) or amylase release values compared with the control group. Similar results were obtained when pancreatic acinar cells were stimulated with a high concentration of acetylcholine (10 microM/L). CONCLUSION: The present results demonstrate that a diet supplemented with virgin olive oil can modify pancreatic cell function as assessed by [Ca(2+)](i) mobilization and amylase release evoked by secretagogues in rat pancreatic acinar cells. A role for fatty acids in calcium signaling is suggested.

Amylases↗
PubMed2002

Identification and quantitation of major carotenoids in selected components of the Mediterranean diet: green leafy vegetables, figs and olive oil.

OBJECTIVE: To characterize the carotenoid content of selected components of the Mediterranean diet commonly eaten by Greek migrants to Melbourne, a population group maintaining a traditional dietary regimen, and who exhibit relatively high circulating carotenoid concentrations and low cardiovascular disease mortality. DESIGN AND SPECIMENS: Opportunistic sampling of wild (sow thistle, amaranth, purslane and dandelion, collected from roadsides and home gardens) and commercially available (chicory, endive) green leafy vegetables and figs in season. Foods were selected on the basis that they are commonly eaten by Greek migrants but not by Anglo-Celtic persons, and had not previously been well-characterized with respect to their carotenoid contents. Extra virgin, cold-pressed olive oil and 'extra light' olive oil were obtained from commercial sources. Specimens were extracted with tetrahydrofuran (or chloroform:methanol for olive oil) and carotenoid contents were quantified using HPLC with UV detection. Two to six specimens of greens and figs were analysed. Dietary intake was assessed by food frequency questionnaire. RESULTS: Wild green vegetables contained high concentrations of lutein (sow thistle>amaranth>purslane>dandelion) and beta-carotene (sow thistle>amaranth>purslane=dandelion). Sow thistle and amaranth contained lutein (15 and 13 mg/100 g, respectively) and beta-carotene (3.3 and 4.0 mg/100 g, respectively) at concentrations greater than that seen in the commercially available species of chicory and endive. Figs contained all major carotenoids appearing in plasma, albeit at low concentrations. Extra virgin cold-pressed olive oil contained substantial quantities of lutein and beta-carotene, but the more-refined 'extra light' olive oil did not. CONCLUSIONS: These components of the traditional Mediterranean diet contribute to the higher circulating concentrations of carotenoids in Greek migrants compared to Anglo-Celtic Australians. SPONSORSHIP: This study largely funded by the National Health and Medical Research Council of Australia (grant no. 974098). Extra virgin olive oil donated by Picuba Foods, Marrickville, NSW, Australia.

Australia↗
PubMed1990

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.

Animals↗
PubMed2005

Potential anti-cancer effects of virgin olive oil phenols on colorectal carcinogenesis models in vitro.

The traditional Mediterranean diet is thought to represent a healthy lifestyle; especially given the incidence of several cancers including colorectal cancer is lower in Mediterranean countries compared to Northern Europe. Olive oil, a central component of the Mediterranean diet, is believed to beneficially affect numerous biological processes. We used phenols extracted from virgin olive oil on a series of in vitro systems that model important stages of colon carcinogenesis. The effect the extract on DNA damage induced by hydrogen peroxide was measured in HT29 cells using single cell microgel-electrophoresis. A significant anti-genotoxic linear trend (p=0.011) was observed when HT29 cells were pre-incubated with olive oil phenols (0, 5, 10, 25, 50, 75, 100 microg/ml) for 24 hr, then challenged with hydrogen peroxide. The olive oil phenols (50, 100 microg/ml) significantly (p=0.004, p=0.002) improved barrier function of CACO2 cells after 48 hr as measured by trans-epithelial resistance. Significant inhibition of HT115 invasion (p<0.01) was observed at olive oil phenols concentrations of 25, 50, 75, 100 microg/ml using the matrigel invasion assay. No effect was observed on HT115 viability over the concentration range 0, 25, 50 75, 100 microg/ml after 24 hr, although 75 and 100 microg/ml olive oil phenols significantly inhibited HT115 cell attachment (p=0.011, p=0.006). Olive oil phenols had no significant effect on metastasis-related gene expression in HT115 cells. We have demonstrated that phenols extracted from virgin olive oil are capable of inhibiting several stages in colon carcinogenesis in vitro.

Anticarcinogenic Agents↗
PubMed2007

Effect of the olive oil phenol hydroxytyrosol on human hepatoma HepG2 cells. Protection against oxidative stress induced by tert-butylhydroperoxide.

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.

Antioxidants↗