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2 Department of Nutrition and Food Science, Centre of Reference in Technology of Food, Faculty of Pharmacy, University of Barcelona, s/n E-08028 Barcelona, Spain; 3 Lipids and Cardiovascular Epidemiology Unit, Institut Municipal d'Investigació Mèdica, 08003 Barcelona, Spain; 4 Oy Jurilab Ltd., Microkato 1, F-70210 Kuopio, Finland; 5 Department Clinical Pharmacology, Rigshospitalet, University Hospital Copenhagen, DK-2200 Copenhagen, Denmark; 6 Atherosclerosis Center CG Descovich, Bologna University, IT-41038, Bologna, Italy; 7 Department Intervention Studies, German Institute of Human Nutrition Potsdam-Rehbruecke, D-14558 Nuthetal, Germany; and 8 Charité-University of Medicine of Berlin, D-10117 Berlin, Germany
* To whom correspondence should be addressed. E-mail: mclopez{at}ub.edu.
| ABSTRACT |
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| Introduction |
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Furthermore, it has also been reported that the adherence to a Mediterranean diet increases the likelihood of controlling arterial blood pressure (BP) (5,6). Although genetic factors seem to be responsible for as much as 2040% of BP variations in the general population (7), epidemiologic data suggest that lifestyle factors, such as dietary habits, are a major contributor to the high prevalence of hypertension (8,9). Olive oil intake, per se, has been inversely associated with both systolic BP (SBP) and diastolic BP (DBP) (5).
Because cardiovascular mortality is much lower in Mediterranean populations than in those from North European and Western countries (10), a shift in the dietary habits of the Northern European population to the traditional Mediterranean pattern likely would be desirable. However, changing well-established dietary patterns is not always easy. There are numerous factors that can markedly influence dietary intake, such as differences in culture, ethnicity, religion, availability of specific foods, and economic development among others (11). Therefore, it may be practical to gradually encourage healthier dietary patterns, beginning with the introduction of small changes.
Our objective was to analyze the effects of a moderate consumption of olive oil in healthy men from non-Mediterranean regions [Northern Europe (Finland and Denmark) and Central Europe (Germany)] and Mediterranean regions [Southern Europe (Italy and Spain)].
| Subjects and Methods |
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The subjects were divided into 3 groups according to the region they were from (North, Central, and South Europe). The protocol was fully explained to all participants. All subjects provided written informed consent. The local institutional Ethic Committees10 approved the protocol.
Study design.
The study was a randomized, cross-over trial with 3 intervention periods of 3 wk and 2 wash-out periods of 2 wk. During the intervention periods, 3 similar olive oils (25 mL/d), differing only in their phenolic concentration (low, 2.7 mg/kg olive oil; medium, 164 mg/kg; and high, 366 mg/kg), were consumed by the men. Daily doses of olive oil were prepared without knowledge of contents in containers delivered to the participants at the beginning of each intervention period. The
-tocopherol concentration for the 3 oils was 111.9 mg/kg. The fatty acid composition was the same for the 3 oils (Table 1). Subjects were examined at baseline and at the end of the study. They recorded their habitual diet for 3 consecutive days at baseline and the end of the study period. Food consumption was converted into corresponding nutrient intake with validated nutrition software from each country (Denmark: DanKost 3000 software, Dankost A/S; Finland: NUTRICA@ version 2.5. software; Germany: PRODI version 4.5. LE 2001; Italy: Dieta ragionata release 3.0. della ESI Stampa Medica SrL; Spain: MediSystem 2000, Conaycyte).
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Plasma total cholesterol (TC), HDL-C, and TG concentrations were measured using enzymatic methods (Roche Diagnostics) (1214). We calculated LDL-C using the Friedewald formula and measured plasma fatty acids by fast GC after transforming them into methyl esters (15).
BP and BMI measurements. BP was measured with a mercury sphygmomanometer after a minimum of 10 min rest in the seated position; the mean of 2 measurements was used for analysis. An easy-calibration precision scale was used to measure body wt (in underwear). Subjects weighed 75.8 ± 9.7 kg, their height was 1.78 ± 0.06 m, and their BMI was 23.8 ± 2.5 kg/m2.
Statistical analysis. Data are presented as means ± SD. A Levene test was performed to check homogeneity of variance. Paired t tests were used for intra-group comparisons and 1-factor ANOVA for inter-group comparisons. Tukey's post hoc tests were performed for multiple comparisons between groups. For performing a more powerful multivariate analysis, general linear models were used to analyze the effect of a moderate consumption of olive oil in the lipid profile and BP values. For each model, the dependent variable was defined as the difference between the endpoint and the baseline values of each of the variables (SBP, DBP, TC, HDL-C, LDL-C, and TG) and the independent variable was the plasma oleic acid level at the end of the study, considered as a biomarker of the olive oil intake. Because age and BMI affect plasma lipid concentrations and BP, they were included in each model as covariates, as were the baseline plasma oleic acid level, the baseline value of each variable under study, the European region the participants were from, the phenolic concentration of the participants' plasma at baseline and at the end of the study, and the sequence in which the men received oil treatments. For all analyses, 2-sided significance was determined at the P < 0.05 level. Analyses were performed using the SPSS statistical software package (version 12.0).
| Results |
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Dietary records. At baseline, energy intake from fat was significantly lower in men from Northern Europe than in those from the other 2 regions (Table 2). While SFA provided the highest percentage of fat in the men from the northern and central regions, in men from the Mediterranean area, around one-half of the energy derived from fat was due to MUFA intake. The amount of cholesterol consumed was significantly higher for men from Central Europe, whereas those from Northern and Southern Europe had intakes that did not differ. Compared with the other 2 groups, baseline vitamin E intake was significantly lower in men from Northern Europe, vitamin A intake was significantly lower in men from Southern Europe, and vitamin B-12 intake was significantly lower in men from Central Europe.
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Plasma fatty acid composition. Baseline plasma oleic acid levels were significantly higher in the Mediterranean men than in the non-Mediterranean volunteers (Table 3). Subjects from Southern Europe had lower plasma palmitic and linoleic acid levels than those from Northern and Central Europe. Men from Northern Europe had lower plasma arachidonic acid levels than men from both other groups.
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| Discussion |
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The daily baseline dietary records showed different dietary habits in Mediterranean and non-Mediterranean countries. A recent study describing the dietary patterns of 10 European countries and their social-demographic determinants, using the comparable inter-country DAFNE (Data Food Networking) data (16), showed that olive oil is the added fat of choice in the Mediterranean region, whereas the Central European and Scandinavian populations have higher intakes of other vegetable oils and animal fats.
It is interesting to note some outcomes of the moderate consumption of olive oil. We expected that plasma oleic acid levels would increase after daily supplementation in all subjects. This increase, however, was not significant in the Italian and Spanish subjects (P = 0.071) due to their habitually high intake of olive oil (10,11), which was clearly reflected in their baseline oleic acid levels. The MUFA to SFA dietary lipid ratio also remained significantly higher in men from Southern Europe than in men from Northern and Central Europe.
Although the participants were allowed to continue their habitual diets, most of the non-Mediterranean volunteers reduced their SFA and PUFA intakes in an attempt to balance their total fat intake. This resulted in a healthier lipid profile at the end of the study. The health benefits of olive oil used to recruit volunteers for the study, together with its ease of use and pleasant incorporation into their habitual meals, could have encouraged the non-Mediterranean subjects to change the quality of their fat intakes.
It has recently been reported that changing the proportions of dietary fat by decreasing SFA and increasing MUFA decreases BP in healthy subjects (17). These results agree with SBP outcomes in the non-Mediterranean participants of this work. In addition, Rasmussen et al. (17) observed that the beneficial effect on BP induced by fat quality was negated by high total fat intake. In our study, the non-Mediterranean participants had high total fat intakes at the beginning of the study and after consuming supplemental olive oil for 9 wk (
34.9% energy). However, despite the high total fat intake, they had lower SBP at the end of the study.
In conclusion, the outcomes of our study suggest that moderate administration of olive oil could be used as an effective tool to reduce SBP of healthy men in those European populations where the Mediterranean diet is not typically consumed. The introduction of olive oil into non-Mediterranean diets should be accompanied by a reduction in saturated fat to improve lipid profiles. Nevertheless, a longer study should be conducted to verify that small changes or modifications in the diet can be made, which would hopefully become habitual.
| ACKNOWLEDGMENTS |
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| FOOTNOTES |
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9 Abbreviations used: BP, blood pressure; CVD, cardiovascular heart disease; DAFNE, Data Food Networking; DBP, diastolic blood pressure; fast-GC, fast gas chromatography; GLM, general linear models; HDL-C, HDL cholesterol; LDL-C, LDL cholesterol; MUFA, monounsaturated fatty acid; SBP, systolic blood pressure; TC, total cholesterol; TG, triglycerides. ![]()
10 University of Kuopio, Finland; Rigshospitalet University Hospital, Copenhagen, Denmark; German Institute of Human Nutrition, Postdam-Rehbruecke, Germany; Charité-University of Medicine of Berlin, Germany; Centro per lo Studio del
Arteriosclerosi e delle Malattie Dismetaboliche "GC Descovich," Policlinico S. Orsola-Malpighi, Bologna, Italy; and the Municipal Institute for Medical Research, Barcelona, Spain. ![]()
Manuscript received 24 July 2006. Initial review completed 22 August 2006. Revision accepted 19 October 2006.
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