virgin olive oil reduces blood pressure in hypertensive elderly subjects

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ORIGINAL ARTICLE

Virgin olive oil reduces blood pressure inhypertensive elderly subjects

Javier S. Peronaa, Julio Ca *nizaresb, Emilio Monteroc, Jos !e M. S!anchez-Dom!ıngueza, Angel Catal!ad, Valentina Ruiz-Guti !erreza,*

aInstituto de la Grasa, Consejo Superior de Investigaciones Cient!ıficas, Avda. Padre Garcia Tejero 4, Sevilla41012, SpainbResidencia Heli!opolis de la Tercera Edad, Junta de Andaluc!ıa, Sevilla 41012, SpaincHospitales Universitarios Virgen del Roc!ıo, Sevilla 41013, SpaindC!atedra de Bioqu!ımica, Facultad de Ciencias Veterinarias, Universidad Nacional de La Plata, La Plata,Argentina

Received 20 December 2003; accepted 14 February 2004

Summary Background & aims: Hypertension is one of the most important risk factorsfor coronary heart disease. Recent studies have pointed out the possibility that virginolive oil (VOO) may lower blood pressure in hypertensive (HT) subjects. However,until the date there is scarce information regarding elderly people. The presentstudy was designed to assess the effect of dietary VOO on blood pressure in medicallytreated hypertensive elderly patients.Methods: 31 medically treated HT elderly patients and 31 normotensive (NT)

elderly volunteers participated in a randomized sequential dietary intervention.Subjects consumed diets enriched in sunflower oil (SO) or VOO for 4 weeks each witha 4-week washout period between them.Results: VOO reduced total and LDL-cholesterol in NT but not in HT (Po0:01) and

the concentrations were lower than in the group consuming SO. In contrast, nosignificant differences were found in the levels of tocopherols among the groupsstudied. Iron-induced oxidation of LDL resulted in a complete loss of monoacylgly-cerols (MG) and diacylglycerols (DG) and a reduction in triacylglycerols (TG) (60–80%), which was found to be greater in HT (Po0:01) with no effect of diet. VOOconsumption normalized systolic pressure in the HT group (136710mmHg)compared to SO (15078mmHg).Conclusion: Dietary VOO proved to be helpful in reducing the systolic pressure of

treated HT elderly subjects. However, a greater resistance to the lowering effect ofVOO of total and LDL-cholesterol and a greater susceptibility to TG oxidation wasdetected in these patients.& 2004 Elsevier Ltd. All rights reserved.

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KEYWORDS

Virgin olive oil;

Elderly;

Hypertension;

Cholesterol;

Tocopherol

*Corresponding author. Tel.: þ 34-5-461-1550; fax: þ 34-5-461-6790.E-mail address: [email protected] (V. Ruiz-Guti!errez).

0261-5614/$ - see front matter & 2004 Elsevier Ltd. All rights reserved.doi:10.1016/j.clnu.2004.02.004

Clinical Nutrition (2004) 23, 1113–1121

Introduction

In elderly people, both isolated systolic hyper-tension and combined systolic/diastolic hyper-tension are considered the most important riskfactors for coronary heart disease morbidity andmortality.1 In fact, hypertension affects morethan one half of the elderly and its prevalenceincreases with age.2 When hypertension is treated,the cardiovascular morbidity and mortality isreduced to a greater extent than could beexpected from the results of trials in middle-agedsubjects.3 However, nutritional supplementationhas acquired an important relevance, partiallybecause many antihypertensive agents elevatelow-density-lipoprotein-cholesterol (LDL) or tria-cylglycerol (TG) concentrations and/or lowerhigh-density-lipoprotein-cholesterol (HDL) concen-trations, paradoxically increasing the cardiovascu-lar risk.4,5

Despite fish oil or n-3 fatty acid supplementationshave been employed as adjuvants in the treat-ment of hypertension, several studies did notfind a reduction in blood pressure of hyperten-sive (HT) patients, when compared with virginolive oil (VOO) supplementation.6,7 We demon-strated that the intake of VOO lowers both systolicand diastolic pressures in normocholesterolemicand hypercholesterolemic HT women when com-pared with a diet enriched in high-oleic sun-flower oil (HOSO).8 In addition, VOO, but notHOSO, also normalized some of the impairedfunctions of the erythrocyte membrane in HT.9

Subsequently, other authors have corroborated ourfindings.10,11

The concentration of antioxidants in VOO hasalso been related to a resistance of LDL tooxidation.12,13 Oxidative modification of LDL hasbeen implicated as an important determinant inthe development of atherosclerosis.14 Susceptibil-ity of plasma LDL to oxidation from differentsubjects ex vivo is highly variable and is related,among other factors, to the TG, polyunsaturatedfatty acids (PUFA) and vitamin E contents.15 In fact,LDL oxidation is increased by adding PUFA to thediet, such as SO, and decreased by adding vitaminE. De Waart et al.,16 reported that supplementationwith vitamin E in the elderly is beneficial forlowering the rate of oxidation of linoleic acid in theLDL of elderly people, whose LDL are moresusceptible to oxidation.17 LDL are also more proneto be oxidized in patients affected by hyperten-sion18 but it that can be prevented adding vitamin Eto the diet since it reduces the susceptibility tooxidative modification of LDL by means of increas-ing oxidation lag time.19

The present work was conducted with the aim ofevaluating the effects of dietary VOO and SO onblood pressure and on the lipid composition of LDLand oxidized LDL (oxLDL) in a group of non-diabeticmedically treated HT elderly people (average age84 yr). In addition, we evaluated the concentrationof a-tocopherol and other vitamins and non-fattyacid constituents of dietary VOO that might berelated to the susceptibility of LDL to oxidation.

Subjects and methods

The study was performed at Residencia Heli !opolis(Junta de Andaluc!ıa, Seville, Spain), a residentialhome for the elderly, where the diet of allparticipants was controlled. 42 women and 20men (31 NT and 31 HT), who were residents atthe beginning of the study, gave written, informedconsent to a protocol approved by the InstitutionalCommittee on Investigation in Humans (HospitalesUniversitarios Virgen del Roc!ıo, Seville, Spain). Allparticipants had been residents of the ResidenciaHeli !opolis for at least 5 years, consequently alltheir habits were completely known. HT volunteershad been suffering from hypertension for at leastthe last 5 years and were medically treated withbeta-blockers and diuretics. None of them wasdiabetic or suffered from glucose intolerance orhypothyroidism. Fasting glucose levels were101.1728.1mg/dl for normotensives (NTs) and forHTs 95.1712.6mg/dl. Cigarette smokers wereexcluded from the study and no case of alcoholabuse was detected among participants.

Diets

The participants were successively fed two dietsenriched in SO or VOO for four weeks each. A 4-week washout period was included between ex-perimental periods, consisting on the habitualdietary fat, comprised of refined oil and a blendof seed oils. Before the study, the health officersrecorded the habitual dietary intake of the parti-cipants during four consecutive weeks, using a 24 hrecall and food frequency questionnaires. Theenergy consumption and nutrient intake werecalculated, approved by a dietician and employedas a basis for the diets of the study. The studieddiets were based on ordinary food and wereplanned for every 4-week period and were revisedevery week. The diet was adjusted to 30% of theenergy as fat, 55% as carbohydrates and 15% asproteins. Oils were added to the diet in a daily doseof 60 g. The fatty acid composition of the oils was

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1114 J.S. Perona et al.

performed by gas chromatography as describedbelow and is shown in Table 1. Three diet sampleswere collected in each experimental period to beanalyzed for their fat content and other nutrients.One investigator was present several times in thekitchen during meal preparation without previousnotification. The energy consumption was approxi-mately 1800 kcal/day. Sodium intake was identicalin both experimental periods.

Blood pressure measurements

Blood pressure measurements were performed inthe morning, after an overnight fast, at the rightbrachial artery in seated participants using amercury-gauge sphyngomanometer. The measure-ments were recorded by the same nurse at theresidential home at the beginning, middle and endof every experimental period. At each visit threeblood pressure measurements were recorded andthe average used to determine eligibility.

Serum lipid and lipoprotein analyses

Venous blood was obtained in fasting status after anovernight period, at the beginning and end of eachperiod of the study. Blood was collected inVacutainers tubes and serum obtained by centri-fugation at 1500 rpm during 30min at 41C. Serumsamples were frozen below �801C until analyzed.Serum total and high-density-lipoprotein (HDL)cholesterol and TG concentrations were measuredby conventional enzymatic methods. Low-density-lipoprotein (LDL) cholesterol concentration wascalculated according to the Friedewald equation.

Isolation and oxidation of low-densitylipoproteins (LDL)

LDL were isolated by density gradient ultracentri-fugation from 4ml of serum (40,000 rpm, 18 h,151C). Ultracentrifugation was performed using aSW 41 Ti rotor in a BECKMAN L8-70M preparativeultracentrifuge (Beckman Instruments, Inc, PaloAlto, USA). Lipid peroxidation was assayed byincubating LDL (1mg of protein) in 0.05M phos-phate buffer, pH 7.4 at 371C, final volume 2ml. Thereaction was started by addition of ascorbate (finalconcentration 0.4mM). Phosphate buffer was con-taminated with sufficient iron to provide thenecessary ferrous or ferric iron for lipid peroxida-tion.

Determination of serum vitamins andsqualene

Squalene was determined by gas chromatographyafter extraction from total lipids using the methoddescribed by Lanzon et al.20 Liposoluble vitaminswere extracted from 500 ml of serum as follows.500 ml of ethanol and 1ml of hexane were addedsequentially. The mixture was centrifuged(3500 rpm, 151C for 10min) and the supernatantcollected. The hexane was evaporated under astream of nitrogen and the vitamins redissolved incholoroform/methanol (2:1, v/v) for injection intothe HPLC system. This system consisted on areversed-phase column (Novapack, 4� 250mm,4 mm) and an elution system composed of metha-nol/acetonitrile (chloroform (9:78:13, v/v/v) thatrun isocratically. A photodiode array detector (PAD996, Waters) was used for a-tocopherol, g-toco-pherol and retinol detection at 290 nm (a-tocopher-ol and g-tocopherol) and 325 nm (retinol),respectively. These compounds were identified byusing commercial standards and quantified bymeans of external standard.

Determination of LDL and oxLDL lipid classes

Total lipids were extracted following a modificationof the method of Rose and Oaklander,21 using 2,6-di-tert-butyl-p-cresol (BHT) as antioxidant. 10 ml oflipids from LDL and oxLDL were dissolved inchloroform/methanol (2:1, v/v) and were injectedin a 2690 Alliance liquid chromatograph (Waters,Milford, USA), controlled by computer (Millenium34 System, Waters, Milford, USA) and provided witha Lichrosphere column (250� 4.6mm, 5 mm particlesize) (Merck, Darmstadt, Germany). The liquidchromatograph was coupled to a light-scattering

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Table 1 Fatty acid composition of the sunflower(SO) and virgin olive oils (VOO) employed in theexperimental diets.

Fatty acid (mg/100mg) SO VOO

16:0 6.470.4 10.971.8n

16:1, n-7 0.170.0 1.170.3n

18:0 1.670.3 2.471.318:1, n-9 t ND 0.370.218:1, n-9 25.171.4 74.670.6n

18:1, n-7 1.670.3 3.570.1n

18:2, n-6 64.571.2 4.570.4n

18:3, n-3 ND 0.670.2n

18:3, n-6 0.970.1 1.170.320:1, n-9 0.470.1 0.270.122:0 ND 0.870.1n

%x7SD: n ¼ 3 ND: not detected.nDifferent from SO Po0.01.

Virgin olive oil reduces blood pressure in elderly 1115

detector (DDL31 Eurosep Ins., Cergy-Pontoise,France). The mobile phase consisted on a ternarysolvent system, starting with 0.8% of 2-propanol inhexane raising the percentage of 2-propanol to3.0% in 8min and then to 10.0% after 17min. Fromminute 17 to minute 22, the percentages of hexaneand 2-propanol were reduced to 0%, whereas thatof methanol was raised to 100%. The flow rate was0.8ml/min. Standard solutions of cholesterol ole-ate, triolein, 1,2-diolein, 2-monoolein, cholesteroland dipalmitoyl phosphatidylethanolamine (Sigma,St. Louis, USA) were used for identification andquantification. For calibration, triplicate runs of sixconcentrations of these standards (0.25 and2.5mg/ml in chloroform/methanol, 2:1) wereinjected. Equations resulting from regressioncurves of these standards were employed forquantification.

Statistical analyses

Values are shown as mean7standard deviation. Thesignificance of the difference among groups wasassessed by analysis of variance (ANOVA) withTukey’s post hoc comparison of the means. Differ-ences were considered significant with a confidenceinterval of 99% (Po0:01). The analyses were donewith Prism v3.0 (GraphPAD Software, San Diego,USA).

Results

During the period of the study, we detected nocardiovascular, nor other metabolic or endocrine

disease among the individuals recruited. Theaverage age of the participants was 84.077.4 yr,and presented an average BMI of 28.875.2 kg/m2

and a whist to hip ratio (WHR) of 0.9170.06. Norelationship was found between the ages, BMI andWHR of the individuals. The content of totalpolyphenols in VOO was 232 ppm and that ofsqualene was 3709 ppm. These compounds werenot detected in SO.

The variations recorded in the blood pressure ofthe elderly people are depicted in Fig. 1. Systolicpressure was normalized in HT by dietary VOO butnot by SO. NT individuals showed values close to139mmHg after the period of SO whereas HTshowed values above to 150mmHg. In contrast,when the subjects consumed the VOO diet both NTand HT presented systolic pressure values close to135mmHg. No significant differences were foundfor diastolic pressure.

The concentrations of serum lipids and lipopro-teins in the group of HT were not significantlymodified after consuming VOO compared to SO(Table 2). In contrast, VOO was responsible for adecrease in total and LDL-cholesterol concentra-tions in NT (Po0:01). However, a concomitantdecrease in HDL-cholesterol and an increase in TGwere also observed (Po0:01). Hypertension did notaffect cholesterol concentrations when patientsconsumed VOO but when consuming SO NT showeda lower TG concentration in serum than HT(Po0:01).

The concentration of g-tocopherol and a-toco-pherol in serum were not modified by either of thediets or affected by hypertension (Table 3). How-ever, the concentration of retinol was significantly

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100

110

120

130

140

150

160

170

SO VOO

Sys

tolic

Pre

ssu

re (

mm

Hg

)

NT HT

0

20

40

60

80

100

SO VOO

Dia

sto

lic P

ress

ure

(m

mH

g)

NT HT

a

b

a a

a

a a a

Figure 1 Systolic and diastolic pressures of NTand HTelderly subjects after consuming sunflower (SO) or virgin olive oildiets (VOO). Mean values within a row sharing the same letter are not significantly different (P40:01).


higher in the elderly after consuming VOO(Po0:01). Unexpectedly, we did not find highersqualene amounts in serum of the subjects afterconsuming VOO than after SO. Indeed, we foundthe highest concentration of this cholesterol pre-cursor in HT after the administration of SO.

Six lipid classes were identified and quantified inthe LDL of the elderly subjects (Table 4), forinstance cholesteryl esters, free cholesterol, TG,diacylglycerols (DG), monoacylglycerols (MG) andphospholipids. The determination of these lipidclasses provided more information about the low-ering in cholesterol observed in the LDL of NT

(Table 2). Indeed, such reduction was due to alower cholesteryl esters concentration and not to adecrease in the amount of free cholesterol. The TGconcentration in LDL was lower in NT after SO(Po0:01), mirroring total TG concentration inserum. In contrast, after VOO, the concentrationof TG and DG was significantly higher in NT(Po0:01). No significant differences were found inthe MG and phospholipid concentrations in LDL.

When LDL underwent iron-induced oxidation, aloss of MG, DG and TG was found (Table 5 andFig. 2). DG and MG could not be detected in oxLDLand TG concentration was reduced in about

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Table 2 Serum lipid levels (mg/dl) of normotensive (NT) and hypertensive (HT) elderly subjects after consumingsunflower (SO) or virgin olive oil diets (VOO).

NT-SO HT-SO NT-VOO HT-VOO

TC 186.2738.1a 184.8740.5a 166.6737.7b 179.2744.2a,b

LDL-C 113.0735.5a 112.0727.9a 99.2732.4b 105.7729.3a,b

HDL-C 57.6717.8a 54.0718.7a 48.1714.9b 51.2717.2a,b

TG 77.6730.0a 94.0733.3b 96.3743.1b 96.6742.6b

Mean values within a row sharing the same letter are not significantly different (P40:01).%x7SD: n ¼ 31:TC: total cholesterol, LDL-C: LDL-cholesterol, HDL-C: HDL-cholesterol, TG: triacylglycerols.

Table 4 Lipid classes composition of LDL (mg/100mg of lipids) of normotensive (NT) and hypertensive (HT)elderly subjects after consuming sunflower (SO) or virgin olive oil diets (VOO).


Cholesteryl esters 41.176.3a 38.875.4a,b 35.77 5.6b 40.174.1a

Free cholesterol 12.771.7a,b 12.070.8a 13.271.3b 13.571.9b

Total cholesterol 53.875.2a 50.875.5b 48.974.5b 53.672.9a

Triacylglycerols 9.371.7a 12.971.9b 15.272.6c 11.872.7b

Diacylglycerols 2.970.3a 2.470.5a 4.870.2b NDMonoacylglycerols 1.870.2a 1.870.1a 2.670.8a 2.270.4a

Phospholipids 32.475.5a 32.075.1a 29.277.5a 32.675.3a

%x7SD: n ¼ 31:Mean values within a row sharing the same letter are not significantly different (P40:01).ND: not detected.

Table 3 Serum liposoluble vitamins and squalene composition (mg/ml) of normotensive (NT) and hypertensive(HT) elderly subjects after consuming sunflower (SO) or virgin olive oil diets (VOO).


g-tocopherol 0.470.1a 0.470.1a 0.470.1a 0.470.1a

a-tocopherol 5.371.1a 5.871.5a 5.570.7a 5.270.9a

Retinol 1.870.3a 2.170.5a 2.670.4b 2.670.5b

Squalene 0.2870.09a 0.3670.12b 0.3370.15a,b 0.2670.09a

%x7SD: n ¼ 31:Mean values within a row sharing the same letter are not significantly different (P40:01).


50–80%. The greatest oxidation of TG occurred inHT (Po0:01) but diet did not affect it. Thereduction in the glyceride fraction occurred con-comitantly to an increase in the cholesterolspecies. The proportion of free and esterifiedcholesterol was increased in LDL after the intakeof either of the dietary oils. Although the choles-teryl ester content found in oxLDL was notsignificantly different among the groups studied,the lowest increase was found in the group of NTafter SO (Po0:01). Oxidation did not affect thephospholipid content of LDL.

Discussion

Newly available data is pointing out that, inaddition to plasma lipids, VOO intake may also

reduce blood pressure in HT and healthy sub-jects.8,10,11 The present work was designed toassess the effects of VOO and SO on serum lipids,the lipid composition of LDL and oxLDL and bloodpressure of medically treated HT elderly people.

Systolic pressure was reduced in HT participantsafter consuming the diet rich in VOO. Unfortu-nately, for the moment there is scarce informationon the effect of dietary oils on blood pressure inaged people. Margolin et al.,4 performed double-blind randomized-controlled studies to comparethe effects of the administration of n-3 (fish oil)and n-6 fatty acids to HT elderly people on bloodpressure, showing a higher reduction of systolic anddiastolic pressures in subjects receiving fish oil.However, some studies failed to find effects of fishoil or n-3 fatty acid supplementation on bloodpressure in treated HTwhen compared to VOO as aplacebo, suggesting that VOO is able to reduceblood pressure to a similar extent. Previously, Ruiz-Gutierrez et al.8 had observed a hipotensive effectof dietary VOO in HT patients compared to anotheroleic acid-rich oil, such as HOSO. VOO, but notHOSO, normalized the altered distribution ofcholesterol and Naþ–Liþ countertransport in theerythrocyte membrane. Although it needs to beelucidated which of the minor constituents of VOOis/are responsible of these effect, on the basis ofthe accumulated data, we suggest that polyphenolsmay play a key role in this regard, since thesecompounds are absent in SO, either the wild type orhigh-oleic. The mechanism of reduction of bloodpressure by polyphenols has been related toendothelium-dependent vasorelaxation via en-hanced nitric oxide.10,22

Classical studies have reported similar effects ofdietary intake of VOO and SO on serum lipidconcentrations of healthy subjects.23,24 However,there is still need of consensus, since recent workshave shown increasing total and LDL-cholesterol

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Table 5 Lipid classes composition of oxidized LDL (mg/100mg of lipids) of normotensive (NT) and hypertensive(HT) elderly subjects after consuming sunflower (SO) or virgin olive oil diets (VOO).


Cholesteryl esters 51.873.8a 52.773.8a 49.175.2a 54.074.3a

Free cholesterol 13.472.2a 12.871.4a,b 13.572.3a 12.071.8b

Total cholesterol 65.272.9a 65.572.4a 62.673.1b 66.073.2a

Triacylglycerols 4.070.5a 2.370.6b 4.670.8a 2.570.2b

Diacylglycerols ND ND ND NDMonoacylglycerols ND ND ND NDPhospholipids 31.372.9a 33.373.4a,b 34.272.6b 33.474.6a,b

ND: not detected.%x7SD: n ¼ 31:Mean values within a row sharing the same letter are not significantly different (P40:01).

Figure 2 Percentage of variation of cholesteryl esters(CE), free cholesterol (FC), total cholesterol (TC) andtriacylglycerols (TG) in LDL due to oxidation in NTand HTelderly subjects after consuming sunflower (SO) or virginolive oil diets (VOO). Mean values within a row sharingthe same letter are not significantly different (P40:01).


concentrations after consuming VOO compared todietary oils rich in n-6 fatty acids25,26 and othershave reported greater cholesterol reductions ofVOO.27,28 These discrepancies may be due todifferences in experimental conditions, includingthe employment of different varieties of olive oil aswe have shown lately.29 In the present study wefound a lower total and LDL-cholesterol concentra-tions in the serum of NT elderly individuals afterconsumption of VOO but not in HT (Table 2),suggesting that these patients would be moreresistant to modifications by diet on serum lipidand lipoproteins concentrations. We previouslyreported a lack of lowering effect of VOO on serumcholesterol in a group of HT postmenopausalwomen compared to HOSO.8 The content ofsqualene, the main hydrocarbon in VOO, has beenconsidered hypercholesterolemic compared withSO.26 We found negligible differences in the serumconcentrations of squalene in NT or HT elderlyindividuals after both diets studied, excluding anyrelationship between squalene concentrations andthe observed variations in serum cholesterol. Veryscarce studies on the influence of VOO on squalenecontent have been carried out and for the momentnone in an elderly population.

To our knowledge this is the first study in which adietary intervention with VOO has been conductedin such an old population of HT individuals. Agingresults in modifications of the risk factors related tocardiovascular disease.30 In the very elderly, bothserum TG and LDL-cholesterol are diminished,31 aswell as antioxidants, due to enhanced of oxidativestress.32 There are a growing number of studiesindicating that antioxidants may be responsible forsome of the protective effects of VOO.33,34 Theconcentrations of a� and g-tocopherol in serum ofelderly people consuming either SO or VOO werenot significantly different. In contrast, the concen-tration of retinol was higher in NT and HT subjectsafter consumption of VOO. Low concentrations ofserum retinol or vitamin A, as well as tocopherols,have been related to the risk of coronary heartdisease35 and hypertension,36 even in elderlysubjects.37 However, the supplementation of thesevitamins in the diet seems to have no relevanteffect on blood pressure at least in HT patientsunder medical treatment,38 unless a very high doseis administrated.39 Additionally, the role of thesupplementation of these compounds on the risk ofCHD is controversial since some interventionalstudies have reported no clear effect.40

Nevertheless, the antioxidant role of thesevitamins on the resistance of LDL to oxidation andthus as determinant of atherosclerosis have beenclearly stated in vitro.14 In order to study the

susceptibility to oxidation of LDL obtained fromelderly people after consumption of VOO or SO, weanalyzed the actual loss of the lipids contained inthose lipoproteins. Very commonly, oxidation in LDLis tested indirectly by measuring espectrophotome-trically the conjugate diene formation or theproduction of lipid hydroperoxides, such as mal-onaldehide (MDA) or thiobarbituric acid reactivesubstances (TBARS).41 The HPLC determination oflipid classes in LDL allows checking the actualmodifications of lipids occurring in LDL due to iron-induced oxidation. We observed a loss of glyceridiclipids (TG, DG and MG), resulting in a proportionateincrease in free and esterified cholesterol. Both DGand MG completely disappeared from LDL in allgroups studied (NT-VO, NT-SO, HT-VO and HT-SO)but the loss of TG was greater in HT, suggesting thathypertension diminishes the protection of LDLagainst iron-induced oxidation in elderly subjects.This is of particular interest since it has beenreported that LDL peroxides and the susceptibilityof LDL to oxidation are increased with aging.17

Frostegard et al.18 have very recently showed thatoxLDL are raised in serum of HT men as determinedby antibody targeting of oxidation epitopes in LDL.In has been stated that an improvement of LDLresistance to oxidation is achieved by bloodpressure reduction42 and vitamin E supplementa-tion.19 However, as no effect of the diet and nodifferences in the tocopherol concentrations werefound, our results support the data raising doubtsabout the antioxidant effect of this vitamin.

The average BMI value of the elderly subjects wasclose to 28 kg/m2, which is usually taken as anindicator of overweight and might bias the resultsof the study. Obesity increases in advancedmaturity, mainly due to changes in the bodycomposition related to age. Such modificationinclude the reduction in height, at a rate of 1–2 cm per year and even quicker after 85 years,resulting in an increase of BMI.43 Heiat et al.44

reviewed data from 444 articles on the associationof BMI and all causes of cardiovascular mortality ingeriatric populations concluding that up to 27 kg/m2 BMI does nor represent a mortality risk in elderlypeople and suggested that the world healthorganization guidelines of BMI may be too re-stricted for this population. Others have evenrecommended that elderly people with BMI valuesbetween 25 and 30 kg/m2 and over 70 years oldshould not be encouraged to lose weight, as it doesnot represent a risk for cardiovascular mortality.45

We conclude that dietary VOO is helpful inreducing the systolic pressure of treated HT elderlysubjects, thus reducing the requirement of anti-hypertensive medication. However, in these

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patients we detected a greater resistance to thelowering effect of VOO in total and LDL-cholesteroland a greater susceptibility to TG oxidationcompared to NT individuals, which was not relatedto tocopherol or squalene concentrations in serum.The differential effects of VOO and SO consumptionon serum squalene content in elderly subjectsshould be further investigated.

Acknowledgements

We are thankful to the director, nurses andassistance personnel of the Residencia de la TerceraEdad Heli!opolis, for their willingness during theperiod of the study. We are also grateful, to GrupoHojiblanca, and in particular to Mr. Mantilla, forsupplying the oils employed and for the analyticalfacilities provided. This work was supported byFEDER funds from the European Community (FEDER1FD97-2288) and from Junta de Andalucia (CAO 01-002).

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virgin olive oil reduces blood pressure in hypertensive elderly subjects

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