Effects of total dietary polyphenols on plasma nitric oxide and blood pressure in a high cardiovascular risk cohort. The PREDIMED randomized trial.

BACKGROUND AND AIM: Hypertension is one of the main cardiovascular risk factors in the elderly. The aims of this work were to evaluate if a one-year intervention with two Mediterranean diets (Med-diet) could decrease blood pressure (BP) due to a high polyphenol consumption, and if the decrease in BP was mediated by plasma nitric oxide (NO) production. METHODS AND RESULTS: An intervention substudy of 200 participants at high cardiovascular risk was carried out within the PREDIMED trial. They were randomly assigned to a low-fat control diet or to two Med-diets, one supplemented with extra virgin olive oil (Med-EVOO) and the other with nuts (Med-nuts). Anthropometrics and clinical parameters were measured at baseline and after one year of intervention, as well as BP, plasma NO and total polyphenol excretion (TPE) in urine samples. Systolic and diastolic BP decreased significantly after a one-year dietary intervention with Med-EVOO and Med-nuts. These changes were associated with a significant increase in TPE and plasma NO. Additionally, a significant positive correlation was observed between changes in urinary TPE, a biomarker of TP intake, and in plasma NO (Beta = 4.84; 95% CI: 0.57-9.10). CONCLUSIONS: TPE in spot urine sample was positively correlated with plasma NO in Med-diets supplemented with either EVOO or nuts. The statistically significant increases in plasma NO were associated with a reduction in systolic and diastolic BP levels, adding to the growing evidence that polyphenols might protect the cardiovascular system by improving the endothelial function and enhancing endothelial synthesis of NO.

Mediterranean diet and non enzymatic antioxidant capacity in the PREDIMED study: evidence for a mechanism of antioxidant tuning.

BACKGROUND AND AIMS: The intake of antioxidant-rich foods may increase the blood levels of non enzymatic antioxidant capacity (NEAC). NEAC takes into account all antioxidants from food and synergistic effects between them. We examined the effect of a 1-year intervention with Mediterranean diet on plasma NEAC and assessed whether it was related to baseline NEAC levels. METHODS AND RESULTS: Five hundred sixty-four participants at high cardiovascular risk were randomly selected from the PREDIMED (Prevención con DIeta MEDiterránea) Study, a large 3-arm randomized clinical trial. Blood NEAC levels were measured at baseline and after 1-year of dietary intervention with 1) a Mediterranean diet supplemented with virgin olive oil (MED + VOO); 2) a Mediterranean diet supplemented with nuts (MED + nuts), or 3) a control low-fat diet. Plasma NEAC was analyzed using FRAP (ferric reducing antioxidant potential) and TRAP (total radical-trapping antioxidant parameter) assays. Plasma FRAP levels increased after 1-year of intervention with MED + VOO [72.0 µmol/L (95% CI, 34.2-109.9)] and MED + nuts [48.9 µmol/L (24.3-73.5)], but not after the control low-fat diet [13.9 µmol/L (-11.9 to 39.8)]. Participants in the lowest quartile of plasma FRAP at baseline significantly increased their levels after any intervention, while those in the highest quartile decreased. Similar results occurred with TRAP levels. CONCLUSIONS: This study shows that a 1-year of MED diet intervention increases plasma TAC level in subjects at high risk for cardiovascular disease. Moreover, the effectiveness of dietary supplementation with antioxidants may be related to baseline levels of plasma NEAC.

Dietary intake and major food sources of polyphenols in a Spanish population at high cardiovascular risk: the PREDIMED study.

BACKGROUND AND AIMS: Epidemiological data have shown an inverse association between the consumption of polyphenol-rich foods and the risk of cardiovascular disease or overall mortality. A comprehensive estimation of individual polyphenol intake in nutritional cohorts is needed to gain a better understanding of this association. The aim of this study was to estimate the quantitative intake of polyphenols and the major dietary sources in the PREDIMED (PREvención con DIeta MEDiterránea) cohort using individual food consumption records. METHODS AND RESULTS: The PREDIMED study is a large, parallel-group, multicentre, randomised, controlled 5-year feeding trial aimed at assessing the effects of the Mediterranean diet on the primary prevention of cardiovascular disease. A total of 7200 participants, aged 55-80 years, completed a validated 1-year food frequency questionnaire (FFQ) at baseline. Polyphenol consumption was calculated by matching food consumption data from the FFQ with the recently developed Phenol-Explorer database on polyphenol content in foods. The mean total polyphenol intake was 820 ± 323 mg day⁻¹ (443 ± 218 mg day⁻¹ of flavonoids and 304 ± 156 mg day⁻¹ of phenolic acids). Hydroxycinnamic acids were the phenolic group with the highest consumption and 5-caffeoylquinic acid was the most abundantly ingested individual polyphenol. The consumption of olives and olive oil was a differentiating factor in the phenolic profile of this Spanish population compared with other countries. CONCLUSION: In Mediterranean countries, such as Spain, the main dietary source of polyphenols is coffee and fruits, but the most important differentiating factor with respect to other countries is the consumption of polyphenols from olives and olive oil.

Total polyphenol excretion and blood pressure in subjects at high cardiovascular risk.

BACKGROUND AND AIMS: Dietary factors are critical for the prevention and treatment of hypertension, but data on the effects of specific nutrients on blood pressure (BP) are scarce. The aim of this study was to assess the relationship between total polyphenol excretion (TPE) in urine, as an objective measurement of total polyphenol intake and BP in an elderly population at high cardiovascular risk. METHODS AND RESULTS: Cross-sectional substudy of 589 high-risk participants entering in the PREDIMED trial. BP was measured and TPE was determined in urine by Folin-Ciocalteu assay. A significant positive association was observed between TPE in urine and daily intake of fruit and vegetables (F&V), coffee or wine after adjusting for potential confounders. The intake of 100 g of F&V (Beta=0.150;P<0.001) had a greater contribution to TPE than 100 mL of coffee (Beta=0.141;P=0.001), and the latter two foods contributed more than the consumption of 100 mL of wine (Beta=0.120;P=0.019). An inverse association was observed between urinary TPE and the prevalence of hypertension. Participants in the highest quartile of urinary TPE had a reduced prevalence of hypertension compared to those in the lowest quartile (Odds Ratio=0.64; 95% confidence interval 0.45 to 0.92; P=0.015). Systolic and diastolic BP were inversely associated with urinary TPE after adjustment for potential confounders (P=0.024 and P=0.003, respectively). CONCLUSIONS: Polyphenol intake, assessed via TPE in urine, was negatively associated with BP levels and prevalence of hypertension in an elderly Mediterranean population at high cardiovascular risk. Participants with the highest intake of polyphenol-rich foods showed the lowest BP measurements.

Olive oil and health: summary of the II international conference on olive oil and health consensus report, Jaén and Córdoba (Spain) 2008.

Olive oil (OO) is the most representative food of the traditional Mediterranean Diet (MedDiet). Increasing evidence suggests that monounsaturated fatty acids (MUFA) as a nutrient, OO as a food, and the MedDiet as a food pattern are associated with a decreased risk of cardiovascular disease, obesity, metabolic syndrome, type 2 diabetes and hypertension. A MedDiet rich in OO and OO per se has been shown to improve cardiovascular risk factors, such as lipid profiles, blood pressure, postprandial hyperlipidemia, endothelial dysfunction, oxidative stress, and antithrombotic profiles. Some of these beneficial effects can be attributed to the OO minor components. Therefore, the definition of the MedDiet should include OO. Phenolic compounds in OO have shown antioxidant and anti-inflammatory properties, prevent lipoperoxidation, induce favorable changes of lipid profile, improve endothelial function, and disclose antithrombotic properties. Observational studies from Mediterranean cohorts have suggested that dietary MUFA may be protective against age-related cognitive decline and Alzheimer's disease. Recent studies consistently support the concept that the OO-rich MedDiet is compatible with healthier aging and increased longevity. In countries where the population adheres to the MedDiet, such as Spain, Greece and Italy, and OO is the principal source of fat, rates of cancer incidence are lower than in northern European countries. Experimental and human cellular studies have provided new evidence on the potential protective effect of OO on cancer. Furthermore, results of case-control and cohort studies suggest that MUFA intake including OO is associated with a reduction in cancer risk (mainly breast, colorectal and prostate cancers).

Characterization of human gene expression changes after olive oil ingestion: an exploratory approach.

Olive oil consumption is protective against risk factors for cardiovascular and cancer diseases. A nutrigenomic approach was performed to assess whether changes in gene expression could occur in human peripheral blood mononuclear cells after oli ve oil ingestion at postprandial state. Six healthy male volunteers ingested, at fasting state, 50 ml of olive oil. Prior to intervention a 1-week washout period with a controlled diet and sunflower oil as the only source of fat was followed. During the 3 days before and on the intervention day, a very low-phenolic compound diet was followed. At baseline (0 h) and at post-ingestion (6 h), total RNA was isolated and gene expression (29,082 genes) was evaluated by microarray. From microarray data, nutrient-gene interactions were observed in genes related to metabolism, cellular processes, cancer, and atherosclerosis (e.g. USP48 by 2.16; OGT by 1.68-fold change) and associated processes such as inflammation (e.g. AKAP13 by 2.30; IL-10 by 1.66-fold change) and DNA damage (e.g. DCLRE1C by 1.47; POLK by 1.44- fold change). When results obtained by microarray were verified by qRT-PCR in nine genes, full concordance was achieved only in the case of up-regulated genes. Changes were observed at a real-life dose of olive oil, as it is daily consumed in some Mediterranean areas. Our results support the hypothesis that postprandial protective changes related to olive oil consumption could be mediated through gene expression changes.

Bioactive effects of olive oil phenolic compounds in humans: reduction of heart disease factors and oxidative damage.

Oxidative stress is defined as an imbalance between the oxidant and antioxidant systems of the body, in favour of the oxidants. Oxidative stress produced by free radicals has been linked to the development of several diseases such as cardiovascular, cancer, and neurodegenerative diseases. Olive oil is the main source of fat of the Mediterranean diet which has been shown to be effective against oxidative stress associated diseases and also with the ageing. Besides its richness in monounsaturated fatty acid, the oleic acid, olive oil contains minor components with antioxidant properties. Here, we update the state of the art, and degree of evidence, of the body of knowledge concerning the protective role on lipids and lipid oxidative damage in humans of the olive oil phenolic compounds.

Effect of olive oil consumption on serum resistin concentrations in healthy men.

Resistin has been linked to atherosclerosis and inflammatory processes in humans. Some polyphenols have been shown to downregulate resistin expression in adipocytes. The effects of olive oil phenolics on resistin are not known; therefore, we investigated the impact of olive oil consumption on serum resistin as a function of the olive oils' phenolic content. In a randomized, controlled, cross-over study 38 healthy German men aged 38+/-2 years replaced their usual consumption of raw fat during 3 periods of 3 weeks each by 25 ml of virgin, common and refined olive oil varying in phenolic content. Serum resistin, blood lipids and urine biomarkers of subjects' compliance were analysed at baseline and at the end of each intervention period. The integration of olive oil in the subjects' habitual diet led to a decrease in total cholesterol (p=0.025) and triglycerides (p=0.013) independent of the content of phenolic compounds in the oil. Serum resistin concentrations were not affected by the olive oils' phenolic content. After low phenolic olive oil consumption, a decrease in serum resistin level was observed compared to medium and high phenolic olive oil (-0.4+/-0.1 ng/ml; p=0.040). Our results suggest that olive oil consumption has only marginal beneficial effects on serum resistin levels.

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.

Antioxidant effect of virgin olive oil in patients with stable coronary heart disease: a randomized, crossover, controlled, clinical trial.

The Mediterranean diet, in which olive oil is the main source of fat, has been associated with a reduced incidence of coronary heart disease (CHD) and low blood pressure levels. Virgin olive oil (VOO), besides containing monounsaturated fat, is rich in phenolic compounds (PC) with antioxidant properties. The aim of this study was to examine the antioxidant and anti-hypertensive effect of two similar olive oils, but with differences in their PC (refined: 14.7 mg/kg versus virgin: 161.0 mg/kg), in 40 males with stable CHD. The study was a placebo controlled, crossover, randomized trial. A raw daily dose of 50 mL of VOO and refined olive oil (ROO) were sequentially administered over two periods of 3 weeks, preceded by 2-week washout periods in which ROO was used. Lower plasma oxidized LDL (p < 0.001) and lipid peroxide levels (p = 0.003), together with higher activities of glutathione peroxidase (p = 0.033), were observed after VOO intervention. Systolic blood pressure decreased after intake of VOO (p = 0.001) in hypertensive patients. No changes were observed in diastolic blood pressure, glucose, lipids, and antibodies against oxidized LDL. Consumption of VOO, rich in PC, could provide beneficial effects in CHD patients as an additional and complementary intervention to the pharmacological treatment.

Bioavailability of phenolic compounds from olive oil and oxidative/antioxidant status at postprandial state in healthy humans.

Olive oil phenolic compounds are generally believed to have beneficial antioxidant effects, but little is known about characteristics of their postprandial bioavailability in natural olive oil at real-life doses. The aim of the present study was to determine the concentrations of olive oil phenolic compounds in urine collected over 24 h (24-h urine) after a bolus ingestion of 25 ml of olive oil with different phenolic content, and to demonstrate the effect of this real-life olive oil dose on postprandial levels of blood lipids and oxidative stress biomarkers, as well as to examine the beneficial effects of olive oil phenols. Oral fat loads of 25 ml olive oil with high, moderate, and low phenolic content were administered to 12 healthy male volunteers in a randomized, controlled, crossover trial. Tyrosol and hydroxytyrosol were absorbed in a dose-dependent manner according to the phenolic content of the olive oil administered. The administered dose of 25 ml, which is close to that used daily in Mediterranean countries, did not induce significant postprandial lipemia nor did it promote an increase of in vivo oxidation markers. With regard to plasma antioxidant enzymes, glutathione peroxidase activity decreased postprandially after low phenolic content olive oil ingestion; however this was not observed after intake of moderate and high phenolic content olive oils. The phenolic content of the olive oils administered may account for the protection of the endogenous antioxidant defenses at postprandial state after ingestion of moderate and high phenolic content olive oils.

Tyrosol and hydroxytyrosol are absorbed from moderate and sustained doses of virgin olive oil in humans.

OBJECTIVE: To investigate the absorption of tyrosol and hydroxytyrosol from moderate and sustained doses of virgin olive oil consumption. The study also aimed to investigate whether these phenolic compounds could be used as biomarkers of virgin olive oil intake. DESIGN AND INTERVENTIONS: Ingestion of a single dose of virgin olive oil (50 ml). Thereafter, for a week, participants followed their usual diet which included 25 ml/day of the same virgin olive oil as the source of raw fat. SETTING: Unitat de Recerca en Farmacologia. Institut Municipal d'Investigació Mèdica (IMIM). SUBJECTS: Seven healthy volunteers. RESULTS: An increase in 24 h urine of tyrosol and hydroxytyrosol, after both a single-dose ingestion (50 ml) and short-term consumption (one week, 25 ml/day) of virgin olive oil (P<0.05) was observed. Urinary recoveries for tyrosol were similar after a single dose and after sustained doses of virgin olive oil. Mean recovery values for hydroxytyrosol after sustained doses were 1.5-fold those obtained after a single 50 ml dose. CONCLUSIONS: Tyrosol and hydroxytyrosol are absorbed from realistic doses of virgin olive oil. With regard to the dose-effect relationship, 24 h urinary tyrosol seems to be a better biomarker of sustained and moderate doses of virgin olive oil consumption than hydroxytyrosol.

Bioavailability of tyrosol, an antioxidant phenolic compound present in wine and olive oil, in humans.

Tyrosol is a phenolic compound present in two of the traditional components of the Mediterranean diet: wine and virgin olive oil. The presence of tyrosol has been described in red and white wines. Tyrosol is also present in vermouth and beer. Tyrosol has been shown to be able to exert antioxidant activity in in vitro studies. Oxidation of low-density lipoprotein (LDL) appears to occur predominantly in arterial intima in microdomains sequestered from antioxidants of plasma. The antioxidant content of the LDL particle is critical for its protection. Thus, phenolics, which are able to bind LDL, could be effective in preventing lipid peroxidation and atherosclerotic processes. The ability of tyrosol to bind human LDL has been reported. We have demonstrated the bioavailability of tyrosol in humans from virgin olive oil in its natural form. Urinary tyrosol increased, reaching a peak at 0-4 h after virgin olive oil administration. Men and women showed a different pattern of urinary excretion of tyrosol. Moreover, tyrosol is absorbed in a dose-dependent manner after sustained and moderate doses of virgin olive oil. In summary, our results suggest that tyrosol from wine or virgin olive oil could exert beneficial effects on human health in vivo if its biological properties are confirmed in in vivo studies.

Capillary gas chromatography-mass spectrometry quantitative determination of hydroxytyrosol and tyrosol in human urine after olive oil intake.

Recent in vitro studies have demonstrated antioxidant properties of some virgin olive oil phenolic compounds. One of the prerequisites to extrapolate these data to an in vivo situation is the knowledge of their bioavailability in humans. In the present work we describe an analytical method which enables us to perform hydroxytyrosol and tyrosol quantitative determinations in human urine. This method was successfully used in bioavailability studies of both phenolic compounds after acute olive oil administration. Virgin olive oil was administered to healthy volunteers after a low phenolic diet. The dose administered of both phenolic compounds was estimated in reference to free forms of hydroxytyrosol and tyrosol present in virgin olive oil extracts before and after being submitted to hydrolytic conditions. These conditions mimic those occurring during digestion. Urine samples were collected before and after acute olive oil intake and analyzed by capillary gas chromatography-mass spectrometry. Hydroxytyrosol and tyrosol urinary recovery increased in response to olive oil administration, obtaining maximal values in the first 4 h. Our results further indicate that hydroxytyrosol and tyrosol are mainly excreted in conjugated form, since only 5.9 +/- 1.4% (hydroxytyrosol) and 13.8 +/- 5.4% (tyrosol) of the total amounts excreted in urine were in free form.

[Coronary disease protective factors: antioxidant effect of olive oil]. / Facteurs protecteurs de la maladie coronarienne: effet antioxydant de l'huile d'olive.

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.

[Olive oil and inhibition of low density lipoprotein oxidation. Role of phenolic compounds]. / Aceite de oliva e inhibición de la oxidación de las lipoproteínas de baja densidad. Importancia de los compuestos fenólicos.

BACKGROUND: To investigate the protective effect of several olive oils with different phenolic composition on low density lipoprotein susceptibility to oxidation. PATIENTS AND METHODS: Refined olive oil (phenolic content: 0 mg/l caffeic acid equivalents [CAE]), common olive oil (0.1 and 0.3 mg/l CAE), and virgin olive oil diluted with refined olive oil (0.1 y 0.3 mg/l CAE), were added to isolated low density lipoprotein. Conjugated dienes formation was monitored after copper-mediated low density lipoprotein oxidation. RESULTS: An increase in the lag time of conjugated dienes formation after copper-mediated low density lipoprotein oxidation was observed linked to olive oil phenolic content (p < 0.0001, ANOVA). Multiple regression analysis showed that phenolics were the most significant antioxidants with 0.1 mg/l--increase in phenolic concentration, adjusted for alpha-tocopherol and beta-carotene, was 72 minutes (95% confidence interval [CI] 64 to 80 min) for common olive oil, and 111 min (CI 95%: 100-123 min) for virgin olive oil. In common olive oil alpha-tocopherol levels were significatively associated with the increase in the lag time (p = 0.003), reaching in virgin olive oil a borderline significant (p = 0.084). CONCLUSIONS: Olive oil containing phenolics showed more antioxidant effect on low density lipoprotein oxidation than refined olive in relation to its phenolic content. The nature of the phenolic content influences the antioxidant capacity of an olive oil.

Protective effect of olive oil and its phenolic compounds against low density lipoprotein oxidation.

The protective effect of phenolic compounds from an olive oil extract, and of olive oils with (extra-virgin) and without (refined) phenolic components, on low density lipoprotein (LDL) oxidation was investigated. When added to isolated LDL, phenolics [0.025-0.3 mg/L caffeic acid equivalents (CAE)] increased the lag time of conjugated diene formation after copper-mediated LDL oxidation in a concentration-dependent manner. Concentrations of phenolics greater than 20 mg/L inhibited formation of thiobarbituric-acid reactive substances after AAPH-initiated LDL oxidation. LDL isolated from plasma after preincubation with phenolics (25-160 mg/L CAE) showed a concentration-dependent increase in the lag time of conjugated diene formation after copper-mediated LDL oxidation. Refined olive oil (0 mg/L CAE) and extra-virgin olive oil (0.1 and 0.3 mg/L CAE) added to isolated LDL caused an increase in the lag time of conjugated diene formation after copper-mediated LDL oxidation that was related to olive oil phenolic content. Multiple regression analysis showed that phenolics were significantly associated with the increase in lag time after adjustment for effects of other antioxidants; alpha-tocopherol also achieved a statistically significant effect. These results indicate that olive oil phenolic compounds protect LDL against peroxyl radical-dependent and metal-induced oxidation in vitro and could associate with LDL after their incubation with plasma. Both types of olive oil protect LDL from oxidation. Olive oil containing phenolics, however, shows more antioxidant effect on LDL oxidation than refined olive oil.

Virgin olive oil phenolic compounds: binding to human low density lipoprotein (LDL) and effect on LDL oxidation.

Oxidation of low density lipoproteins (LDL) appears to occur predominantly in arterial intima in microdomains sequestered from antioxidants of plasma. Therefore phenolic compounds which are able to bind LDL are good drug candidates for the effective prevention of lipid peroxidation and atherosclerotic processes. Plasma from healthy volunteers on nonsupplemented diets was incubated with virgin olive oil phenolic extracts (0-200 mg/l, caffeic acid equivalents). Phenolic compounds in LDL were measured by high-performance liquid chromatography-diode array detection (HPLC-DAD). Copper-mediated LDL oxidation was performed, and conjugated dienes formation was monitored. After plasma preincubation with olive oil phenolic compounds (OOPC), an increased OOPC-concentration dependent was observed in the total phenolic content of LDL (p < 0.001, ANOVA) as well as in the lag time before conjugated diene formation (p < 0.001, ANOVA). Rutin and four phenolics with flavonoid-like spectra were found to be bound to the LDL control. These phenolics, together with tyrosol which was not present in the LDL control, significantly increased in LDL (p < 0.05) after plasma incubation with OOPC. These results show the ability of tyrosol to bind LDL in vitro and the capacity of virgin olive oil phenolics to protect other phenolic compounds previously bound to LDL. These results provide further evidence that phenolic compounds bound to LDL are likely to protect LDL from oxidation.