Author information1. Centro de Investigación Cardiovascular CSIC-ICCC Hospital de la Santa Creu i Sant Pau - Pavelló del Convent Sant Antoni MariaClaret; Barcelona, 167 08025, Spain2. School of Healthcare Science, John Dalton Building - Manchester Metropolitan University; Manchester, M1 5GD, UK3. Faculty of Health - Edge Hill University; Ormskirk, L39 4QP, UK
AbstractNatural health products (NHP) which include minerals, vitamins and herbal remedies are notgenerally considered by medical practitioners as conventional medicines and as such are notfrequently prescribed by health centre’s as either main-line or supplemental treatments. In the fieldof cardiovascular medicine, studies have shown that typically, less than half of patients sufferingfrom coronary syndromes chose to take any form of NHP supplement and these products are rarelyrecommended by their medical practitioner. Vascular/endothelial cell damage is a key instigatorof coronary arterial plaque development which often culminates in thrombosis and myocardialinfarction (MI). Current treatment for patients known to be at risk of primary or secondary (MI)includes lipid lowering statins, anti-clotting agents (e.g. tissue plasminogen activator; tPA) and drugsfor stabilization of blood pressure such as beta-blockers. However, evidence has been building whichsuggests that components of at least several NHP (e.g. aged garlic extract (AGExt), resveratroland green tea extracts (GTE)) may have significant vascular protective effects through reductionof oxidative stress, lowering of blood pressure, reduction in platelet aggregation, vasodilation andinhibition of abnormal angiogenesis. Therefore, in this review we will discuss in detail the potential ofthese substances (chosen on the basis of their potency and complimentarity) as anti-atheroscleroticagents and the justification for their consideration as main-line additional supplements orprescriptions.Keywords
IntroductionAccording to a World Health Organization Fact Sheet(EURO/03/06) cardiovascular disease (CVD) is thenumber one killer in Europe and world-wide, withheart disease and stroke being the major cause ofdeath in all 53 Member States. It has in fact beendescribed as a true pandemic, with no respect forborders. Figures show that 34,421 (23% of all non-communicable diseases) of Europeans died fromCVD in 2005. The report also highlighted the factthat there is approximately a 10-fold difference inpremature CVD mortality between Western Europeand countries in Central and Eastern Europe (i.e.
there is a higher occurrence of CVD amongst thepoor and vulnerable). The problem for the EuropeanUnion is that there is a direct correlation betweenthe premature death rate and the viability ofcountries’ economies. Although improvements inunderstanding have helped to reduce the numberof Western European dying from CVD and relateddiseases further advances will require a clearerunderstanding of the pathobiological mechanismsresponsible for the development of atherosclerosisand myocardial infarction. Approximately 75% ofacute coronary events are associated withdisruption of atherosclerotic plaques, development
of which takes place over several decades of life,(early vessel damage beginning during child-hood)and whose susceptibility to instability andthrombosis is largely dependent on a number of
known risk-factors (dyslipidemia, arterialhypertension, hyperglycaemia and diabetes) [1].
Key features of coronaryatherosclerotic plaquedevelopmentIn the early stages of vessel damage prior to plaqueformation, chronic minimal injury caused by sheerstress particularly at arterial bi-furcations,narrowing or directional changes leads tointraluminal endothelial damage and dysfunction.Concomitantly, pro-inflammatory intracellularsignalling pathways are recruited which lead totranscriptional up regulation of expression ofgrowth factors (e.g. vascular endothelial cell growthfactor, platelet-derived growth factor and fibroblastgrowth factor-2) cytokines (e.g. tumour necrosisfactor-alpha and MCP-1), adhesion molecules (e.g.intracellular adhesion molecule-1 and vascularendothelial cell adhesion molecule) andchemoattractant proteins [2]. Endothelial celldamage, activation and up-regulation of adhesionmolecules encourage the attraction of platelets, T-cells, and macrophages which engulf excesscholesterol transform into foam cells and help toproduce fatty streaks-some of the earliestpathological sign of plaque development [3].Endothelial dysfunction is known to impair theproduction and bioavailability of nitric oxide(protective against atherosclerosis) and thereforeprotection of these cells against damage and/orincreasing the circulating nitric oxide levels usingpharmacological agents could have clinical benefitfor high risk candidates [4, 5].As more platelets and immune cells aggregate at adamaged region, the increased cytokine productionleads to local cellular proliferation, and transmissionof activating signals to the adventitial vasa vasorumwhich become activated and migrate through thelayers of the artery to help feed the now growingplaque [6, 7].Actively growing plaques often remain stable withthick fibrous caps and contain a high proportionof smooth muscle cells. In these cases, arterialremodelling eventually results in a gradualnarrowing of the lumen resulting in, patientsymptoms such as angina. The mechanismsresponsible for determination of the developmentof vulnerable unstable plaques rather than stableones is still unknown although there is evidencefor the involvement of a number of key factors,namely, oxidative stress and formation of oxidizedlow density lipoproteins, diabetes, high orfluctuating blood sugar levels and formation ofadvanced glycation end-products (AGEs), theprocess of inflammation and tumour-likeangiogenesis.
The importance of plaquevascularisationPlaque angiogenesis is now accepted to have afundamental role in the pathophysiologicaldevelopment of atherosclerosis, providing nutrientsto the developing and expanding intima and alsopotentially creating an unstable haemorrhagicenvironment prone to rupture. The expression ofintimal neovessels is directly related to the stage ofplaque development, the presence of symptomaticdisease and the risk of plaque rupture. Inatherosclerosis, intimal neovascularization arisesmost frequently from the dense network of vesselsin the adventitia, adjacent to a plaque, rather thanfrom the main artery lumen. The irregular nature ofblood vessel formation has been likened to tumourangiogenesis, and hence the factors responsible fortheir growth may be different from those seenduring normal wound healing. Our previous studiesand those of others have suggested thathaemorrhagic, leaky blood vessels from unstablecarotid plaques proliferate abnormally. Theserelatively large caliber but immature neovessels arepoorly invested with smooth muscle cells andpossess structural weaknesses which maycontribute to instability of the plaque by facilitationof inflammatory cell infiltration and haemorrhagiccomplications Therefore; inhibition of angiogenesismight be an important target for prevention ofdevelopment of active, unstable plaque lesions [7].
Oxidative stressThe process of oxidative stress starts early indeveloping lesions, when inflammatory cells and/or dysfunctional mitochondra caught in the arterialwall begin to secrete reactive oxygen species (ROS)[8]. ROS are able to stimulate cellular apoptosisdirectly, and also to oxidize low-density lipoproteins(LDLs) [9]. Oxidised LDLs (oxLDLs) promote smoothmuscle cell and macrophage gelatinase productionas well as stimulating pro-inflammatory signallingpathways through tissue factor (TF), interferonregulatory factor-1 (IRF-1) and Toll-like receptor-2(TLR2), thereby contributing significantly to plaqueinstability and thrombosis [10]. Similarly,particularly in diabetic patients, a combination ofchronic hyperglycaemia and enhanced oxidativestress results in production and deposition ofadvanced glycation end-products (AGEs) in thecoronary arteries, which activate intracellularprocesses through their receptor receptor for AGEs)(RAGE) inducing further oxidative stress, promotinginflammation via NFkappaB, and increasing ECMaccumulation [11]. Reduction of plaqueinflammation and oxidative stress could help toprevent plaque erosion and ultimately thrombosis.
Current preventative and treatment strategies for CAD
Throughout Europe and the EU, patients recognizedby general practitioners and within hospitals to beat risk of developing coronary artery disease (CAD)(genetic profiles, risk factor analysis, presence ofsymptomatic disease etc.) or with a known historyof CAD, may be offered a variety of prescriptionsdesigned to reduce the risk of first or subsequentMI. Aspirin and other anti-platelet medicines suchas clopidogrel help to prevent blood clots, whilstnew anti-platelet agents including prasugrel andticagrelor have shown reduced iscaemic efficacyand greater safety for patients with acute coronarysyndromes (ACS) [12]. Statins (inhibitors of HMG-CoA) are commonly prescribed to patientspresenting with high total cholesterol levels or highHDL/LDL ratios when one or more related riskfactors are also present. Rosuvastatin, one of themore recently distributed statins appears to haveseveral other beneficial, preventative actions(greater than other statins) besides its lipid-lowering ability for patients with CAD. Rosuvastatinhas been shown to preserve coenzyme Q10,ubiquinol and concomitantly increase HDL-C levels[13] significantly induce plaque regression byreducing plaque volume [14], and reduced vascularendothelial cell growth factor (VEGF) levelsfollowing myocardial revascularization potentiallyreducing plaque neovascularisation [15]. Beta(adrenoceptor antagonists)-blockers and calcium-
channel blockers, reduce chronic resting heart-rate(an independent predictor of CAD mortality) andreduce blood pressure/hypertension, possibly themost important single factor associated with CAD[16], whilst angiotensin-converting enzyme (ACE)inhibitors and angiotensin II receptor blockers alsoreduce blood pressure and may also have aprotective effect against development ofatherosclerosis by ameliorating endothelialdysfunction [17].
Limitations of current treatmentsLimitations of the current treatments are clear, side-effects and long-term complications apart, theknown effects of these medications show onlymarginal interactions with some of the majorprocesses known to be responsible for creation ofunstable plaques i.e. oxidative stress combinedwith inflammation and angiogenesis (with thepossible exception of some types of statin which isthe subject of ongoing research). As well as this, asignificant amount of evidence exists that patientswith none-acute cardiac disease are markedly moreunlikely to receive guideline-recommended therapy[18]. Hence, the majority of at-risk individualscurrently only start medication after the onset ofsymptoms at which time plaque development andarterial remodelling is evident or has alreadyoccurred.
Current use of NHP in clinicalpracticeDiet has long been known to be a modifiable riskfactor for CHD with Mediterranean diets andconsumption of fish, fruit and whole grain all havingbeneficial effects [19]. People with diets containinghigh levels of substances, with anti-oxidantproperties, such as vitamins E and C, and beta-carotene, tend to live longer and more healthily.A search through PubMed using the terms “naturalhealth products” and “CAD” reveals only 21 hits,one of the most recent by Shukla et al. [20],describing profound cardiovascular protective
effects of nutritional supplements such asflavonoids, olive oil, lycopene, resveratrol and soyin epidemiological and clinical studies. A far moreinteresting picture is seen when examiningindividual substances by literature analysis (seebelow). Most importantly, a recent study byAlherbish et al. [21] who conducted a survey onpatients admitted with acute vascular disease,discovered that a wide variety of NHPs are usedby patients including vitamins and minerals (73%),herbal products (20%) and amino acids/essentialfatty acids etc. (35%), however, the healthprofessionals themselves rarely included NHPs aspart of their medication profile.
Evidence for the protectiveproperties of AGExt, Resveratroland GTE in CVDVery few studies have analyzed in detail orretrospectively compiled data by systematicanalysis, on the effects of dietary supplements onarterial disease. One such study examined 38published studies (clinical trials) examining theeffects of NHPs on arterial stiffness measured bypulse-wave velocity [22]. The results showed thatin a majority of trials, omega-3 supplementation,isoflavones, and flavonoids produced significantreductions in arterial stiffness. There wasinsufficient data no make conclusions in respect ofother substances including herbal medicines, andgarlic. Here we will focus on analysis of the dataconcerning three key substances to provide
evidence of their potential cardio-vascularprotective effects.
Evidence for the protective propertiesof AGExtIn vitro studies have demonstrated that AGExt andin particular its most active components, the water-soluble cysteinyl moieties S-allylcysteine and S-allylmercaptocysteine are exceptionally powerfulanti-oxidant phytochemicals, protective againstoxidative stress (by scavenging reactive oxygenspecies and increasing superoxide dismutaselevels) and inhibition of subsequent cellulardamage [23, 24]. AGExt was shown to suppressCD36 scavenger receptor expression onmacrophages, decrease binding of nuclear proteinsto a PPARγ pathway, and inhibit Dil-labelled OXLDLuptake [25]. Similarly, black AGExt demonstrated
anti-inflammatory properties when administered tohuman umbilical vein endothelial cells (HUVEC) bypreventing tumour necrosis factor-alpha (TNFα)-induced expression of adhesion molecules (VCAM-1and ICAM-1) and inhibiting NF-κB transcriptionfactor expression as well as reducing monocyteadhesion and ROS generation [26, 27]. Hence invitro studies demonstrate a potential use for AGExt(which has no specific side-effects and can be takenin high potentially pharmacologically effectivedoses) in reducing oxidative stress, inflammation,and providing endothelial protection against sheerstress damage. Can these effects prove translatablein vitro? Very few studies have investigatedinteractions between AGExt and pharmacologicallyactive substances used to treat patients with CVD,although there are not thought to be any particularnegative synergistic effects [28]. In 2009, Budoffet al. [29] conducted a randomized clinical trial toassess if AGExt could retard the progression of sub-clinical atherosclerosis. 65 patients were treated forone year with AGExt (250 mg) together with vitaminsupplements daily. After one year, patientsreceiving the AGExt showed reduced coronaryartery calcium and increased vascular reactivity(measured by temperature rebound). Totalcholesterol, homocysteine, MDL-LDL auto-
antibodies and apoB-immune complexes weredecreased whilst HDL, apoB and Lp (a) were allsignificantly increased. In conclusion, this is the firststudy to demonstrate improvement in oxidativemarkers, vascular function and a significantreduction in the progression of atherosclerosis inassociation with dietary AGExt supplementation inhumans.AGExt also reduced blood pressure (960 mg/day;systolic BP reduced by 10.2 mmHg; p = 0.03) [30],and inhibited production of AGEs and glycation-induced cross-linking in vitro [31] Figure 1. AGEs,produced by chronic exposure of proteins to highsugar levels are particularly prevalent in patientswith diabetes. When they bind to the receptor forAGEs (RAGE), they activate cellular signallingpathways associated with inflammation, generationof oxidative stress and ROS and are associated withpremature development of atherosclerotic diabeticlesions, rich in leukocyte infiltrates [32, 33].Components of AGExt (N-acetylcysteine) and AGExtitself have been shown to reduce expression ofRAGE, endothelial cell adhesion molecules, NF-κB,MDA, ROS generation and matrixmetalloproteinases culminating in plaquestabilization in apoE-deficient mice [34].
Resveratrol has strong anti-oxidativeand anti-inflammatory propertiesTrans -resveratrol, a polyphenol, and the majorgrapevine phytoalexin (3,5,4´-trihydroxystilbene;Figure 2) has attracted a lot of attention in the
last couple of years due to its extremely potentanti-oxidative and anti-inflammatory capacity andits potential use in the treatment of vasculardisease and prevention or attenuation ofatherosclerosis [35]. This group of anti-oxidants isthought to be responsible for the ‘French paradox’
Figure 1
Figure 1 captionA, AGExt (0–56 mg/ml) inhibition of dimer and trimer production in BSA exposed to high glucose(0.5 M; a-b, controls) in vitro for 21 days (c-h; 0, 7, 14, 28, 42, 56 mg/ml).B, Lysozyme incubatedin the absence (lane a) or presence of 0.5 M glucose (b–i) for 35 days and the effect of 0, 7, 14,28, 42, 56, 70 and 84 mg/ml of AGExt on dimerization. Arrows indicate a significant reduction indimmer and trimer formation in the presence of AGExt.
where a low mortality rate for CAD exists in thepopulation despite their diet of high fat andsmoking [36]. In vitro and in vivo studies haveidentified a multitude of potentially protectiveeffects of this compound. For example, Balestrieriet al., [37], demonstrated that resveratrol or indeedred wine alone could significantly prevent TNF-α-induced reduction in endothelial cell progenitor(EPC) cell number at physiological concentrationswhich could positively impact on re-endothelizationof damaged vessels. Resveratrol was also shown toblock Ca2+ influx in thrombin-stimulated platelets
and to block ADP, collagen and thrombin inducedplatelet aggregation through a pathway which mayinvolve inhibition of thromboxane A2 [38]. Similarly,resveratrol was shown to inhibit human plateletaggregation stimulated by collagen andconcomitantly induce platelet apoptosis throughactivation of caspases-9, 3, and 8 as well as gelsolinand actin cleavage [39]. Prevention of aggregationcoupled with apoptosis may represent an importantmechanism for reduction in thrombotic events.
Resveratrol also inhibited both endothelial cellmigration and MCP-1-induced monocyte cellchemotaxis, which could potentially reduceneointimal vascularisation and monocyterecruitment into a growing plaque [40]. Regarding
inflammation, roscovitine is a potent inhibitor of NF-κB activation, other inflammatory gene expression(e.g. IL-6, IL-8), endothelial cell adhesion moleculeexpression including ICAM-1 and monocyteadhesiveness to endothelial cells (and recruitment
Figure 2
Figure 2 captionSchematic showing the structure of resveratrol and some of its most potent effects on intracellularsignalling associated with prevention of EC activation and unstable plaque development. Itspotent anti-oxidant, anti-inflammatory and EC protective effects are included here and are thoughtto be the main reason for its cardio-protective effects and ability to inhibit plaque de-stabilization.
into the artery wall) in an Akt-dependent manner[35, 41]. Resveratrol also inhibits cyclooxygenaseand hydroperoxidase functions thereby reducinginflammation even more potently [42]. Using anapoE knockout mouse model, Norata et al. [43]showed that animals fed with a supplementcontaining cathechin, caffeic acid and resveratrol,had significantly smaller plaques after 8 weeks(36–40%) in the aortic sinus and ascending aortamainly due to a reduction in inflammatoryinfiltration and expression of MCO-1, MIP-1α,MIP-1β, CCR1, CCR2 and ET1 in the vascular wall.Similarly, Kim et al. [44] showed that oraladministration of resveratrol suppressed intimalhyperplasia in a wire-injured femoral artery mousemodel. Their further examination of culturedsmooth muscle cells revealed inhibition of PDGF-induced ROS and cell proliferation as well asincreased expression of Nrf2 and anti-oxidantresponse element reporter activity associated withHO-1 induction. This data was in agreement withwork performed by Brito et al., [45], who showedthat resveratrol could inhibit oxLDL-induced smoothmuscle cell proliferation via inhibition of the PI3K/Akt/mTOR/p70S6K pathway.Endothelial cell function is known to be improvedin the presence of resveratrol through potentiationof endothelial NO synthase (eNOS) via activationof PPARα and SIRT1 in vascular endothelial cellsand diabetic rats in vivo [38, 46]. In monocytesfrom diabetic patients resveratrol, counteracted thepro-atherosclerotic effects of high glucose levels byreducing super-oxide production through activationof mitochondrial signalling pathways involvingSIRT1-FOXO. E-selectin was also down-regulated[47]. Studies with type-1 diabetic rats have shownthat treatment with resveratrol (10 mg/kg)prevented impairment in eNOS and nNOS-dependent vasodilation in cerebral blood vessels.eNOS and nNOS were also increased whilst super-oxide dismutase was reduced suggesting arestorative function for vascular tissue andoxidative stress [48]. Nitric oxide regulates vasculartone, causes endothelium-dependent vasodilation,and decreases platelet aggregation. In addition itacts as an anti-oxidant, anti-proliferative and anti-inflammatory molecule giving it a key role in theinhibition/prevention of atherosclerosis [49]. Amultitude of studies have also shown a significantreduction in oxidative stress in a variety of
cardiovascular-implicated cells including bloodmononuclear cells (decreased malondialdehydeconcentration), human platelets (reduction inperoxynitrite-induced oxidation), super-oxidescavenging in damaged rat myocardial tissue andinhibition of LDL oxidation ([50] for a review).Other studies show the enormous potential clinicalapplications of this compound from demonstrationsof its complete lack of toxicity in humans even athigh doses, to its lipid lowering capability inmammalian models and general ‘reduction inmodifiable risk factors’ [51, 52] and protection ofcardiomyocytes against apoptosis [53].
Flavanols and other compounds in greenand black tea extractsGreen and black tea and green and black teaextracts are a potent source of flavanols(catechins), phenolic acids and flavonoids, with thecatechin (−)-epigallocatechin-3-gallate (EGCG;Figure 3) perhaps being the most abundant [54].Studies have shown that these substancesdelivered as an extract from de-caffeinated tea(455 mg/day) could reduce hemodialysis-inducedROS generation and pro-inflammatory cytokineexpression in patients [55]. Cross-sectional,randomized controlled and prospective populationstudies have shown that tea intake and/or increaseddietary tea flavonoids reduced the risk ofcardiovascular disease, with consistent datademonstrating enhancement of NO production andconcomitant improvement of endothelial functionas well as reduction in total cholesterol levels andLDL cholesterol [56]. In one particular population-based prospective cohort study, (the Ohsaki study),40,530 persons from Northern Japan were enrolled,and data demonstrated an inverse relationshipbetween CVD mortality and tea consumption [57].Ras et al. [58] showed by meta-analysis of ninestudies that tea consumption was directlyassociated with increased (40%) flow-mediateddilation of the brachial artery (a measurement ofendothelial function), and Tinahones et al., [59]using the same methodology also showedconcomitant reduction in oxLDL levels in patientstaking green tea extract supplementsdemonstrating potential protection against CVD.
These polyphenols were also shown to significantlyreduce serum glucose and lipid peroxidation levelsin alloxan diabetic rats [60]. In vivo studies haveshown that these green tea extracts appear to haveinsulin-like activities, with EGCG inhibiting intestinalglucose uptake via the sodium-dependent glucose
transporter SGLT1 [61]. In vitro, tea extracts wereshown to inhibit endothelial cell plasminogenactivator inhibitor-1 (PAI-1; inhibits fibrinolysis andincreases the risk of thrombolysis) through apathway involving PI-3 K/Akt, again, suggestingthey may contribute to cardiovascular protection
Figure 3
Figure 3 captionRepresentative diagrams showing the interaction between EGCG and important signallingpathways associated with nuclear response gene activation and subsequent inflammation andoxidative stress. Key: EGFR, Endothelial Growth Factor Receptor; ROS, Reactive Oxygen Species;IGF-1R, Insulin Growth Factor-1 Receptor; PAI-1, Plasminogen Activator Inhibitor-1; NF-κB, NuclearFactor-kappa-B; FAK, Focal Adhesion Kinase.
[62]. Other studies have demonstrated that greentea extracts reduced plasma triglycerides, insulinresistance and oxidative stress in insulin-resistantWistar rats which suggests a potential protective
role against diabetes-associated prematuredevelopment of CVD in patients [63].
Should NHP be prescribed asmain-line drugs and/orsupplements for patients at riskof MI?A substantial amount of data including thatprovided above strongly suggests that either aloneor possibly in combination (in the form of a superpill), substances derived from natural healthproducts such as EGCG, resveratrol and s-allylcysteine, may have important cardiovascularhealth benefits. Although much of the data is basedon work carried out in vitro (mostly to determinemechanisms of action) and using animal models, asignificant amount of recently reported data fromclinical trials now suggests these productsprescribed alone or in combination may prove tobe important alternative or additional main-lineprescription drugs. Many of these bioactivephytochemicals have synergistic effects makingmulti-extract combinations more efficient fortargeting more than one target and also meaningthat lower oral doses can be used. For example,Baile et al. [64] demonstrated that a mixtureincluding resveratrol and quercetin was able toreduce adipogenesis in ovariectomized rats, anda number of studies have showed increased anti-tumour activity of polyphenolic mixtures. However,so far, there are very few studies examining thepotential benefits of these mixtures in protectionagainst or amelioration of CAD and secondarycomplications.Hollman et al., [65] recently concluded that whilstin vitro studies, in vivo models of disease andretrospective studies strongly suggest thatpolyphenol-rich products could have beneficialeffects, and that circulating markers of CVD such asoxLDL, total anti-oxidant capacity, F2-isoprostanesand ox-LDL) are often reduced, prospective studiesare lacking, and causal relationships have not yetbeen reliably found. The authors go on to suggestthat a direct effect of these bioactive compoundsis highly unlikely as metabolism during ingestionwould result in lower serum circulating levels than
those of other existing anti-oxidants. Furthermore,much more detailed work needs to be applied tounderstanding fully the mechanisms of action ofthese substances and how each interacts with themost important factors (inflammation, oxidativestress, angiogenesis, diabetes and hypertension)associated with early-medium levels of arterialdamage, plaque development and ultimatelysymptomatic CAD. Smoliga et al., [66] describesusing resveratrol as an example the lack ofunderstanding of pharmokinetics of this compoundin human metabolism, long-term toxicity studiesand drug-drug interactions, all of which must beestablished prior to consideration or justification ofits use in routine clinical practice. The situationwould become even more complex in the designof a super pill composed of several ingredientstargeting more than one anti-atheroscleroticpathway. In vitro studies demonstrated that higherdoses of EGCG were toxic to rat hepatocytes(100–500 μg/ml) and caused pancreatic β-celldamage in streptozotocin-induced diabetic rats(5 mg/kg/day) [67, 68], confirming the importanceof further studies.Nevertheless, the striking potential benefits of thethree substances we have reviewed as well asothers originating from for example soy, olive oiland cocoa should be continued to be investigated,with justification, as the world of vascular biologyand in particular the devastating disease ofatherosclerosis is desperately in need ofidentification and approval of novel therapeutics.Therefore, at the present time this group of naturalproduct-derived substances may represent the bestnew pharmacological preventative/protectivetreatment strategy. So far, the numbers of in vivostudies examining the active ingredients of thesesubstances are still limited, the major activemolecules remain to be identified and synergisticeffects studied in detail before we are ready tocontemplate realistic clinical trials in associationwith detailed comparisons with existingpharmacological agents used for treatment of themajor CAD/cerebrovascular risk factors.
Author’s contributionsMS and GM drafted the manuscript; LB, NA and QW
edited and provided additional sections. All authorsread and approved the final manuscript.
AcknowledgementsWe would like to thank the Fundacion BBVA and PIVfor their generous support of Professor Mark Slevinthrough their award of Chair in Clinical Biomedicineat the ICCC, St Pau Hospital, Barcelona.This workwas also supported by the Spanish Ministry of
Science (SAF2006-10091 to L.B.), Instituto de SaludCarlosIII (CIBEROBN-CB06/03 to L.B.), and RyC(RyC2007-01466 to M.B.-P.). We also acknowledgesupport from the Nutricia Foundation.
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