Oleic Sunflower Oil Into VLDL Triacylglycerols of Hypertensiv
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European Journal of Clinical Nutrition (1999) 53, 687±693 ß 1999 Stockton Press. All rights reserved 0954±3007/99 $15.00 http://www.stockton-press.co.uk/ejcn Incorporation of dietary triacylglycerols from olive oil and high- oleic sun¯ower oil into VLDL triacylglycerols of hypertensive patients V Ruiz-Gutierrez1*, JS Perona1, YM Pacheco1, FJG Muriana1 and J Villar2 1Instituto de la Grasa, CSIC; and 2Unidad de HipertensioÂn Arterial y LõÂpidos, Servicio de Medicina Interna, Hospital Universitario Virgen del RocõÂo, Seville, Spain Objectives: To establish whether the ingestion of diets enriched with olive oil or high-oleic sun¯ower oil may produce changes in the composition of VLDL triacylglycerols from hypertensive patients. It could be relevant for the uptake and metabolism of triacylglycerol-derived metabolites by extrahepatic tissues. Design: Patients were assigned to the diets in a random-order sequence. Subjects: The participants were 24 hypertensive patients recruited from a religious community. Interventions: The study was conducted over two four week periods with a four week washout period between both MUFA diets. Results: Dietary olive oil kept in balance the content of saturated fatty acids and decreased the content of arachidonic acid in VLDL triacylglycerols. HOSO diet reduced the content of palmitic acid and increased the content of linoleic acid. There was also a decrease in trioleate-glycerol and an increase in tripalmitate-glycerol of VLDL after the MUFA diets, but these effects were more pronounced in the HOSO group. Intake of olive oil decreased the content of disaturated triacylglycerols and increased the content of dioleate-containing triacylgly- cerols. A decrease in palmitate-dioleate-glycerol after dietary HOSO was observed. Olive oil (but not HOSO) promoted the presence of long-chain PUFA of n-3 family at the sn-2 position of VLDL triacylglycerols. Conclusions: Our data indicate that olive oil and HOSO, providing a similar concentration of MUFA (oleic acid), differ in the formation of VLDL triacylglycerols in hypertensive patients. Sponsorship: This study was supported by a grant (ALI96-0456 and OLI96-2126) from the CICYT, Spain. Descriptors: VLDL; oleic acid; triacylglycerols; olive oil; high-oleic sun¯ower oil; hypertension; human Introduction atherogenic index (total cholesterol=HDL cholesterol) and the LDL : HDL cholesterol ratio in the plasma of normo- Recommendations to intake monounsaturated fatty acids cholesterolaemic and hypercholesterolaemic hypertensive (MUFA)-rich oils were one of the emergent strategies in patients (Ruiz-Gutierrez et al, 1998a). However, olive oil the last years for modulating the plasma lipid pro®le in but not HOSO had in¯uence on the normalising of struc- humans (Heyden, 1994; Katan et al, 1994). Accordingly, tural and functional alterations of erythrocyte cell mem- the so-called Mediterranean diet with a high content of brane in patients affected with essential hypertension MUFA is actually associated with a low incidence of (Muriana et al, 1997a, b). This raises the question of coronary heart disease (CHD) (Keys et al, 1986). whether other lipoproteins rather than LDL and HDL Olive oil contains a high amount of MUFA (mainly cholesterol are important in regulating cellular processes oleic acid (18:1 n-9)) and predominates in Mediterranean when blood pressure is higher than normal. dietary patterns. Diets supplemented with olive oil are Indeed, there are increasing evidences that relate pre- reported to have bene®cial effects on plasma lipids and mature CHD and the metabolism of triacylglycerol-rich lipoprotein pro®le in hyperlipidaemic patients (Nydahl et lipoproteins (Ginsberg et al, 1995; Criqui, 1998). Among al, 1994), but the effects on healthy subjects are still this heterogeneous group of large lipoprotein particles, controversial (Truswell & Choudhury, 1998). In addition, VLDL are secreted mainly by the liver and their chief recent studies have shown that not only olive oil but also function is the transport of endogenously synthesised high-oleic sun¯ower oil (HOSO) may reduce the risk for triacylglycerols into extrahepatic tissues (Thompson, CHD, both oils having a similar effect in diminishing the 1994). Formation of remnant particles and conversion of VLDL to LDL are dependent upon removal of triacyl- *Correspondence: Dr V Ruiz-Gutierrez, Instituto de la Grasa (CSIC), glycerol core molecules by lipolytic pathways, such as Apartado 1078, 41012 Seville, Spain. Contributors: VR-G, JSP, YMP and FJGM conducted most laboratory those mediated by hepatic lipase and lipoprotein lipase, analyses and were blinded to the dietary assignments. JV was in charge of targeting cells with fatty acids for either energy or storage the enrolement of the participants, and was present twice a week in the (Deckelbaum et al, 1992). The fatty acid pattern of kitchen during the preparation of the meals and remained blinded along triacylglycerols in VLDL appears to be in¯uenced by the with the subjects to changes in VLDL triacylglycerol composition. fatty acid composition of dietary fats, so that the metabolic Guarantor: Dr V Ruiz-Gutierrez. Received 30 October 1998; revised 24 February 1999; accepted 15 fates of VLDL and the clearance of triacylglycerols may March 1999 be markedly altered (Campos et al, 1995; Montalto & Incorporation of dietary triacylglycerols V Ruiz-Gutierrez et al 688 Bensadoun, 1993). However, the effects of dietary tria- cholesterol intake was maintained during the three diet cylglycerols on the composition of VLDL in hypertensive periods at 280 ± 300 mg=d. Dietary instructions were given patients are unknown. by a dietitian before entry into the study. Each participant Interestingly, olive oil and HOSO may contain similar was told what food items should be eaten for breakfast, amounts of MUFA (oleic acid) but the oils differ in their lunch, dinner, and in-between meals. No other food items triacylglycerol composition (Perez-Jimenez et al, 1995; except mineral water, coffee, and tea were allowed to be Carelli & Cert, 1993). More importantly, olive oil but not consumed during the study periods. Three duplicate food HOSO may reduce the systolic and diastolic blood pres- portions corresponding to each weekday were collected and sures in healthy subjects (Ruiz-Gutierrez et al, 1997) and homogenised to be analysed for their fat content and other hypertensive patients (Ruiz-Gutierrez et al, 1996). These nutrient. Different menus were prepared as previously observations suggest a possible link between dietary tria- described (Perez-Jimenez et al, 1995). Virgin olive oil cylglycerols and the mechanisms involved in the regulation (Olea europaea, Extra, Baena, Spain) or HOSO of blood pressure. In this present study, we focus our (Helianthus annuus, Coreysa, Seville, Spain) was used for investigation on determining the effects of olive oil and cooking and salad dressing and was occasionally spread on HOSO intake on triacylglycerol composition of VLDL bread slices. To avoid any isomerisation, only oils obtained from plasma of patients affected with essential hyperten- after the ®rst frying were used. Fatty acid composition, sion. Total fatty acid composition and sn-2 positional triacylglycerols and fatty acids at sn-2 position of the oils distribution of fatty acids in VLDL triacylglycerols were are depicted in Tables 2 and 3. also evaluated. Blood sampling and biochemical determinations Methods During the last days of each period, blood samples were obtained from fasting (12 h) patients by venous puncture Subjects, experimental design and diets into EDTA-containing (1 g=L) tubes. Plasma was separated Twenty-four hypertensive volunteers aged 55.7 Æ 3.6 y by centrifugation at 15006g at 4C for 30 min. Lipoprotein were recruited for this study (Table 1). The criterion for fractions were isolated from fresh plasma samples by hypertension was a systolic blood pressure 140 mmHg centrifugation at 105 0006g at 4C for 20 h with the use and a diastolic blood pressure 90 mmHg recorded on at of sequential ¯otation (Schumaker & Puppione, 1986). least three different occasions after the subject had rested VLDL were harvested at density 1.006 kg=L (Havel et al, supine for 10 min. Before enrolment, all participants had a comprehensive review of their medical history, as well as physical examination and a clinical chemistry analysis to Table 2 Fatty acid and triacylglycerol compositions of the virgin olive exclude the possibility of any secondary cause of hyperten- oil (VOO) and high-oleic sun¯ower oil (HOSO) sion. None of them had diabetes mellitus, hypothyroidism VOO HOSO or received any antihypertensive drug or another treatment affecting lipid metabolism. No history of alcohol abuse or mol=100 mol cigarette smoking was detected. All subjects gave their Fatty acid informed consent before participating in the study. 16:0 11.79 4.30 The study was conducted over two four week periods, 18:0 2.79 4.72 during which each participant ate olive oil or HOSO diets, 18:1 n-9 n-7 79.22 80.18 18:2 n-6 3.45 9.44 including a washout (four week) period between the two 18:3 n-3 0.60 0.06 MUFA diets. Assignment was in a random order sequence Others 2.24 1.30 and in a crossover design. The washout period was long Saturated 15.67 9.96 enough to ensure the re-establishment of basal conditions. Monounsaturated 80.28 80.54 Polyunsaturated 4.05 9.50 The study included an initial 28 d period during which all Triacylglycerola,b participants consumed a similar diet (baseline) that con- POP PLS 3.12 0.23 tained 30% of energy as fat (11% saturated fatty acids PPoO PLP 0.58 NDc (SFA), 16% MUFA and 3% PUFA), 22% as protein and POS 1.42 0.35 48% as carbohydrate. Olive oil and HOSO diets were POO 29.45 9.63 PLO PoOO 4.33 2.05 characterised by a lower amount of SFA (6%) and a SOO 5.27 10.32 higher amount of MUFA (21%). The consumption of OOO 45.82 63.21 olive oil and HOSO was 50 g=d, indicating that both OLO 6.54 6.71 oils contributed around 75% of total dietary fat.