1

Dietary intake of fruit and vegetables and risk of diabetes mellitus and cardiovascular diseases Lydia A. Bazzano, MD, PhD, Department of Medicine, Beth srael Deaconess Hospital, Boston, Massachusetts, USA 2 WHO Library Cataloguing-in-Publication Data Bazzano, Lydia A. Dietary intake oI Iruit and vegetables and risk oI diabetes mellitus and cardiovascular diseases |electronic resource| / Lydia A. Bazzano. Background paper Ior the Joint FAO/WHO Workshop on Fruit and Vegetables Ior Health, 1-3 September 2004, Kobe, Japan. 1.Fruit2.Vegetables3.Diet4.Diabetes mellitus - epidemiology5.Cardiovascular diseases - epidemiology6.Review literatureI.Title. ISBN92 4 159285 0 (NLM ClassiIication: WB 430) Copyright World Health Organization (WHO), 2005. All Rights Reserved. The inIormation in the various pages oI the WHO web site is issued by the World Health Organization Ior general distribution. The inIormation presented is protected under the Berne Convention Ior the Protection oI Literature and Artistic works, under other international conventions and under national laws on copyright and neighboring rights. Extracts oI the inIormation in the web site may be reviewed, reproduced or translated Ior research or private study but not Ior sale or Ior use in conjunction with commercial purposes. Any use oI inIormation in the web site should be accompanied by an acknowledgment oI WHO as the source, citing the uniIorm resource locator (URL) oI the article. Reproduction or translation oI substantial portions oI the web site, or any use other than Ior educational or other non-commercial purposes, require explicit, prior authorization in writing. Applications and enquiries should be addressed to the programme responsible Ior the page used. The designations employed and the presentation oI the inIormation in this web site do not imply the expression oI any opinion whatsoever on the part oI the Secretariat oI the World Health Organization concerning the legal status oI any country, territory, city or area or oI its authorities, or concerning the delimitation oI its Irontiers or boundaries. The mention oI speciIic companies or oI certain manuIacturers' products does not imply that they are endorsed or recommended by the World Health Organization in preIerence to others oI a similar nature that are not mentioned. Errors and omissions excepted, the names oI proprietary products are distinguished by initial capital letters. The World Health Organization does not warrant that the inIormation contained in the web site is complete and correct and shall not be liable whatsoever Ior any damages incurred as a result oI its use. The named author alone is responsible Ior the views expressed in this publication. Electronic publication only 3 Dietary intake of fruit and vegetables and risk of diabetes mellitus and cardiovascular diseasesLydia A. Bazzano, MD, PhD, Department of Medicine, Beth srael Deaconess Hospital, Boston, Massachusetts, USA 1.|ntroduct|on Despiterecentadvancesinpreventionandtreatment,cardiovasculardisease(CVD) remains a major public health problem in both developed and developingcountries.Once consideredadiseaseoItheindustrializedworld,itisnowapparentthatCVDisapublic healthmenaceworldwide.TwiceasmanydeathsIromCVDsnowoccurindeveloping countriesasindevelopedcountries(1).CurrentlyCVDsaccountIor10.3oItheglobal burdenoIdiseaseand30.9oImortality(2).Worldwide,approximately200million people suIIer Irom CVDs, and diabetes, heart disease and stroke are responsible Ior nearly 17milliondeathseachyear,comparedtoadeathrateIromHIV/AIDSoI3million(2-4).Furthermore,IiveoIthetop10riskIactorsIornoncommunicablediseaseworldwideare elevatedbloodpressure,tobaccouse,alcoholconsumption,cholesterol,andobesity(1).WiththeexceptionoImoderatealcoholconsumption,theseIactorsallacttoincreasethe risk oI CVDs.TheworldwideburdenoIdiabetesmellitushasalsobeenincreasingrapidlyalong withincreasesinobesityandCVDs.In1985,itwasestimatedthatapproximately30 millionpeopleworldwidehaddiabetes(5);adecadelaterthisestimatehadrisento135 million (6).In 2000, the global burden oI diabetes was estimated to be 171 million and this is projected to increase to at least 366 million by the year 2030 (7).A large proportion oI this increase is expected to occur in developing countries due to population growth, ageing, lackoIphysicalactivity,andobesity.TheimpactisexpectedtobegreatestinChinaand India.Inaddition,ratesoItype2diabetes,associatedwithinsulinresistanceand accountingIormorethan90oIallcases,areincreasinginyoungerage-groups.Given theincreaseindiabetesindevelopingcountriesandtheyoungerageoIincidence,itis predictedthatby2030,themajorityoIpersonswithdiabetesindevelopingcountrieswill be aged 45-64 years, hence losing some oI their most productive years to disease, disability 4 ordeath(6).TheIeasibilityoIpreventionoIdiabetesbyliIestyleinterventionshasbeen demonstratedbystudiesinChina,Canada,theUSA,andseveralEuropeancountriesin recentyears (8-10).Given the prevalence oI diabetes and CVDs, preventingevena small proportionoIcaseswouldsavehundredsoIthousandsoIlivesandyearsoIlost productivity, and avoid vast amounts oI health-care expenditure. DiethaslongbeenlinkedtothedevelopmentoIobesity,diabetes,andCVDs,and dietarymodiIicationisoneoIthecornerstonesoIchronicdiseaseprevention.Thehealth beneIitsoIadietrichinIruit,vegetables,andlegumes(e.g.beans,peasandlentils,also commonlycalledpulsesandsometimesincludedasvegetables)havebeenrecognizedIor sometime.ThereisasubstantialamountoIevidencethatnutrientscontainedinIruitand vegetables such as dietary Iibre, Iolate, antioxidant vitamins, and potassium, are associated with lower risk oI CVDs.However, the precise mechanisms responsible Ior the eIIects oI theseindividualnutrientsremainpoorlyunderstood.Moreover,theexaminationoIsingle nutrientsinrelationtoCVD-riskmayignorethebiochemicalcomplexityoIwholeIoods. GiventhatdietaryadviceiseasiertounderstandandimplementiIprovidedintermsoI wholeIoods,itisimportanttoexaminethedirectrelationshipbetweenwholeIoodintake and the development CVDs and diabetes (11).Research is beginning in this direction with intriguing results which are summarized in this review. 2.|ssues re|ated to ana|ys|s of fru|t and vegetab|e |ntake 2.1 0|etary assessment of fru|t and vegetab|e |ntake Several diIIerent approaches to measuring an individual`s dietary intake have been used in prospectiveepidemiologicstudies.Eachapproachhasitsadvantagesandlimitations. MethodsoIdietaryassessmentgenerallyinvolveobtainingobservationsoIaparticipant`s Ioodintake,aswiththe24-hdietaryrecallorIoodrecordmethods,orattemptstogetat average or usual Iood intake by inquiring about the Irequency oI consumption oI diIIerent Ioods(12).ManycohortstudieshaveadoptedtheIoodIrequencyquestionnaire(FFQ)to minimizeday-to-dayvariationbyassessingaveragelong-termdietaryintakeand,most importantly,todiscriminateindividuals'dietarypatternsandrankthemaccordingly(13).5 The validityand reliability oIFFQs have beenassessed using detailed dietaryrecords and suitablebiochemicalmarkersandhavebeenreportedtobehighincohortsoIcooperative participants (13, 14). However, the construction oI the Iood list is a critical element oI this methodandmayaIIectthevalidityoIresultsobtained(15).Foodlistsmustbeculture-speciIic in order to provide useIul inIormation (16).While the 24-h dietary recall and FFQ areamongthemostcommonly-usedmethodsoIdietaryassessmentinlarge-scale epidemiologicstudies,othersincludetheIoodrecordanddiethistorymethods.TheIood record method involves participants recording a detailed description oI all Ioods consumed withinaspeciIiedperiodoItime,usuallyseveraldays.Thediethistorymethodinvolves collectingthreeIormsoIdietaryinIormation:adetailedinterviewtoassessparticipants` usual consumption oI speciIic Ioods, a cross-check Iood Irequency list, and a 3-day dietary record.These methods are described in greater detail on page. 2.2 6|ass|f|cat|on of fru|t and vegetab|es ThedeIinitionsoI'Iruitand'vegetablesarenotuniversallyagreedupon,butgenerally includetheediblepartsoIplants.DiIIerenttypesoIIruitandvegetablesdiIIerwidelyin theirnutrientcontentand,inrecognitionoIthis,nationalandinternationalagencies recommendIruitandvegetableconsumptionIromdiversegroups,Irequentlybasedon nutrientcontentandIorm.Inaddition,preparationIrying,peeling,usingbakingsodain cookingwater,andstorageconditionsheat,air,light,andhumidity,aIIectthenutrient content oI Iruit and vegetables. These issues are considered in greater detail on page.Fruit and vegetables diIIer in their nutrient content as groups, the manner in which theyarepreparedandeaten,andtheamountsinwhichtheyareeatendaily.Such diIIerenceshaveimportantimplicationsIoranalysisoIIruitandvegetableintakeand chronicdiseaserisks.Forexample,intheEuropeanProspectiveInvestigationintoCancer andNutrition(EPIC)studyoIIruitandvegetableintakeandcancerrisk,Iruitand vegetableswereanalysedseparately.ItwasIoundthatIruitappearedtohavemore protective associations than vegetables in casecontrol and cohort studies Ior several types oI cancers. It is possible that the amount and manner in which Iruits were consumed across Europe, in contrast to vegetables, mayhave impacted these results.These aspectsoI Iruit 6 and vegetable consumption areimportant considerations in anyanalysis or review oI their eIIects on chronic disease.Inthisreview,Iruitsandvegetablesaretreatedasacombinedentity.ManyoIthe studieswhichprovidethebasisoIthisreviewhavecombinedthesetwogroupsoIIood, althoughseveralalsoprovideseparateanalysesIoreach.Forexample,intheir investigationoIIruitandvegetableintakeandglycosylatedhaemoglobinlevelsinthe population,SargeantandcolleaguesincludedweeklyintakeoIspeciIictypesoIIresh Iruitapples, oranges, pears, and green leaIy vegetablescabbage and broccoli, and other vegetablespeas,carrots,beans,andtomatoes(17).Theatherosclerosisriskin communities(ARIC)studyincludedlegumessuchasbeans,peasandlentils,aswellas potatoes (but not Iried potatoes) in their vegetable category (18). Similarly, Gillman et al. includedlegumes,potatoes,andpotatochips(Iries;Irites)intheirclassiIicationoI vegetables (19).Potato diIIers Irom all other commonly-consumed vegetables in its energy density(muchhigher),nutrientdensity(muchlowerasaratiotototalenergy),glycaemic index and load (much higher), and the likelihood oI its presence in Iast Iood (Iries or chips). Inaddition,energyconsumedintheIormoIpotatoprobablyexceedsthatIromallother vegetables in some developed countries. For these reasons, the above studies may seriously underestimate the protective eIIect oI Iruit and vegetables, as the potato was not examined separately. 7 2.3 The ro|e of ju|ces WhilejuicesareIrequentlyincludedaspartoItheclassiIicationoIIruitandvegetables, they are clearly diIIerent in Iorm and lack much oI the Iibre oI the whole Iruit or vegetable.In addition, they are oIten sweetened with a variety oI substances which contribute to their energydensity but not to any protective role in the development oI chronic diseases. The roleoIIruitorvegetablejuicesasdistinctIromthatoIthewholeIruitandvegetableshas notbeenwellstudied.However,thebeneIicialhealtheIIectsoIconsumingIruitand vegetables are attributed, at leastin part, to their antioxidantactivity which is alsopresent inmanyIruitjuices(20).Forexample,severalstudiespointtopomegranatejuiceasa source oI protective antioxidant compounds (21).With citrus juices, the vitamin C content haslongbeenconsideredtoprotectagainstoxidativestressandatheroscleroticprocesses.Other polyphenolic compounds in citrus juices are also being investigated Ior their potential roles in the prevention oI lipid peroxidation and atherosclerosis (22). A recent intervention study supplemented 38 healthy human volunteers with a powdered Iruit and vegetable juice concentrateandtestedtheirvasomotorresponsesaIterahigh-Iatmeal.AIterconsumption oI juice concentrate daily Ior Iour weeks prior to testing, the detrimental eIIect oI the high-Iat meal was blunted whereas there was no eIIect oI placebo (23). In addition, many juices are rich in potassium which has been shown to reduce blood pressure and may be related a lowerriskoIstroke.Hence,whilejuiceconsumptionislessidealthanwholeIood consumptionIorthepreventionoIchronicdiseasesandobesity,therearemanybeneIicial eIIects which must also be considered. 2.4 8tat|st|ca| ana|ys|s of nutr|t|ona| data Day-to-day variation in an individual`s dietary intake about their true mean intake is termed intra-individualvariation.VariationbetweenthetruemeanintakesoIindividualswithina populationistermedinter-individualvariation(24).Intra-individualvariationindiethas importantconsequencesIorthestatisticalanalysisoInutritionaldata.Using24-hdietary recallandIoodrecordmethods,Liuandcolleaguesdemonstratedthatreductionsinthe magnitudeoIcorrelationcoeIIicientsmayoccurduetolargeintra-individualvariationsin 8 nutrientintake,whichinturnreducesthestatisticalpoweroIastudytotesthypotheses whenmeasurementerrorduetointra-individualvariationisconsiderable(24).Semposet al.demonstratedthatseveraldaysoIdietarymeasurementaregenerallyrequiredtoavoid majordilutionoIthecorrelationcoeIIicienti.e.,biasingthecorrelationcoeIIicient describingtherelationshipbetweenaIoodornutrientoIinterestandanoutcomeoInull value (25). Because oI thisinherentdiIIicultywithdietary data, the usualcriteria Iorcausality mustbeadjustedinstudiesoInutritionalepidemiology.ThemagnitudeoIassociations betweendietanddiseaseisoItensmallcomparedtoassociationsinotherepidemiologic Iields,perhapsbecauseeveryoneisexposedtoIoodIrombirthandaccuratemeasurement oI the exposure is extremely diIIicult.It is Iar more common to Iind risk estimates oI 0.8 to 1.2ratherthantwoIoldorgreater.Verystrongriskestimatesaresouncommonthatthey maybeconsideredsuspicious,butweakassociationsarealsooItenviewedwithcaution because they may be explained by bias.However, in nutritional studies, weak associations mayhaveimportantpublichealthimplicationsbecauseexposurestodietaryIactorsareso common.There is a considerable range oIopinionconcerning aguideline Ior judging the strength oI association in nutritional studies.Potischman and Weed suggest a statistically-signiIicant risk estimate oI at least 20 higher or lower risk to be a positive Iinding, while a risk estimate oI 40-50 higher or lower may be considered a strong Iinding (26). 2.5 6onfound|ng by corre|ated ||festy|es and hea|th hab|ts PersonswhoconsumelargeamountsoIIruit,vegetables,legumes,andnutrientssuchas Iolateandpotassium(muchoIwhichisprovidedbytheseIooditems),mayhaveother liIestyleIactorswhichcouldreducetheirriskoICVDs.Forinstance,personswithhigh intakesoItheseIoodsandnutrientsmaybemorephysicallyactive,educated,andless likely to smoke or consume high levels oI saturated Iat, than theircounterparts with lower intakes(13,27).MoststudiesoInutritionalexposuresanddiseaseoutcomesadjustIor potential conIounders such as age, race, sex, level oI education, physical activity, cigarette smoking,regularalcoholconsumption,andtotalenergyintake.Manystudiesalsoadjust Ior other components oIdiet,given that otherIoodsornutrientsmay alsobe conIounding 9 Iactors.ForexampleintheDietandNutritionalSurveyoIBritishAdults,aprincipal componentsanalysisrevealedthatpeoplewhoatewhole-mealbreadweremorelikelyto drinklow-IatmilkandeatmoreIruitandvegetables,whereasthosewhoatemorewhite bread were more likely to drink more whole-Iat milk and eat more Iried Ioods and less Iruit and vegetables (28, 29). Despite these adjustments, as in all observational studies, imperIect measurementoIconIoundingvariablesandunmeasuredpotentialconIoundersmaystill bias study Iindings. 2. |ntake of nutr|ents versus who|e foods While all dietary assessment methods collect inIormation in terms oI Ioods, Ior a variety oI reasons this inIormation is oIten converted into data on nutrients.The main reason is that theuseoIdataonnutrientsrelatesdirectlytobiological,chemicalandmetabolicstudies (30).In addition, iIa particular nutrient is related to disease, as Iorexample, dietary Iatty acidcompositiontocoronarydisease,analysisoIasingleIoodorIoodgroupwhich contributesonlymodestlytototaldietaryintakeoIcholesterolmaynotdemonstratea relationship to disease (31). One drawback oI using nutrients to represent dietary exposure isthatthedemonstrationoIalackoIassociationIoraparticularnutrientmayleadtothe incorrectassumptionthatdietdoesnotcontributetotheetiologyoIaparticulardisease.AnotherlimitationoItheuseoInutrientdatainanalysisisthatIoodsmaynotbe completely represented by their nutrient content values (32).RepresentingdietaryintakeintermsoIIoodshasitsownadvantagesand limitations.UsingIoodsastheexposureoIinterestismostdirectlyrelatedtodietary recommendations.BecauseindividualsmanipulatetheirdietthroughIoodchoices,dietary advicephrasedintermsoIIoodsiseasierIorthelaypublictounderstandthanthesame advice phrased in terms oI nutrient intake (11). In addition, recommendations may be made concerningtheconsumptionoIparticularIoodsevenwhenthespeciIicbeneIicial componentchemicalsremainunknown,asinthecaseoIIruitandvegetableconsumption andlungcancer.EpidemiologicstudieshaveshownthatahighintakeoIcarotenoids, primarily Irom yellow-range Iruit and green leaIy vegetables, is associated with lower rates oIlungcancer(33-37).Ontheotherhand,todate,randomizedclinicaltrialsoIcarotene 10 supplementationhaveshowneithernoeIIectorslightlyincreasedratesoIcancer(38-40).DietaryrecommendationsIromgovernmentbodiestoincreaseIruitandvegetable consumption are based primarily on observational evidence regarding Iood intake (30, 41). Foodsareextremelybiochemicallycomplexandcontaincompoundswhichmay interact with one another.Thus although a Iood or Iood group contains large amounts oI a certainnutrient,thepresenceoIothercompoundsmaydecreasethebioavailabilityoIthat nutrient.For example, legumes, and in particular dry beans, contain high concentrations oI minerals such as iron, but the bioavailability oI iron Irom legumes is poor (42). ThereIore, theeIIectoIaparticularIoodinthehumanbodycannotbecompletelydescribedbythe eIIectsoInutrientssingly.AlthoughtwoIoods,suchasyogurtandmilk,mayhavevery similar nutrient values, they can produce diIIerent physiological eIIects (32).Thus ideally, epidemiologic studies oI both Ioods and nutrients should be conducted.NationalandinternationalhealthagencieshavedevelopedIood-basednutritional guidelines(FBDGs)IormanyoIthereasonsnotedabove.ThereportoIarecentWorld Health Organization meeting Ior the purposes oI developing dietary guidelines summarizes this reasoning,stating,'There areanumberoIreasons Ior developingFBDGs.First, diets aremadeoIIoodswhicharemorethanmerecollectionsoInutrients.Unlikenutrients, Ioodsanddietshavecultural,ethnic,socialandIamilymeanings,whichcanbe incorporatedintotheFBDG.Second,allthebiologicalIunctionsoIIoodcomponentsand their health eIIects have not been identiIied. II the Iocus is on a single nutrient, the beneIits oItheconsumingthesecompoundsinIoodsmaynotberealized.Third,thecombinations oI nutrients in various Ioods can have diIIerent metabolic eIIects. Fourth, methods oI Iood processingandpreparationalsoinIluencethenutritionalvalueoIIoods.Finally,thereis goodevidenceIromanimal,clinicalandepidemiologicalstudieswhichindicatesthat speciIicdietarypatternsareassociatedwithreducedriskoIspeciIicdiseasesandFBDGs can encourage such practices (43). 3.Potent|a| mechan|sms by wh|ch fru|t and vegetab|es may protect aga|nst 6V0s and d|abetes 11 ManyconstituentsandIunctionalaspectsoIIruitsandvegetablesmayberesponsibleIor theirapparentprotectiveeIIectsonthedevelopmentoIdiabetesandCVDs.Amongthese, theIibre,potassium,Iolate,andantioxidantcontentoIIruitsandvegetables,alongwith their low glycaemic load and potential to aid in weight management, are likely to contribute mosttotheireIIectsonriskoIdiabetesandCVDs.OthercomponentsoIIruitand vegetables, such as minerals and phytochemicals, may also play a role in the prevention oI chronic diseases. Themechanisms bywhich these constituents maycontribute to reducing the risk oI CVDs and diabetes are reviewed in this section. 3.1 F|bre Fruit, vegetables, and cereals are the major sources oI dietary Iibre. Dietary Iibre has been showntodelaytheabsorptionoIcarbohydratesaIteramealandtherebydecreasethe insulinemicresponsetodietarycarbohydrates(44).InonemulticentrestudyoI2909 healthyyoungadultsaged1830years,aIteradjustmentIorconIoundingIactors,dietary Iibreintakewasstronglyandinverselyassociatedwithbodyweight,waist-to-hipratio, Iastinginsulinlevels,and2-hpost-glucoseinsulinlevels(45).Inaddition,severallarge prospectivecohortstudieshaveshowninverseassociationsbetweendietaryIibreandrisk oI developing type 2 diabetes (46-51).Data Irom the Health ProIessionals Follow-up Study and Irom the Nurses Health Study support an inverse association between dietary Iibre and thedevelopmentoIdiabetes(46,47).Inthesetwostudies,investigatorsIoundastronger associationIorcerealIibrethanIorIibreIromIruitandvegetables.Meyeretal.Iounda similarinverseassociationintheIowaWomen`sHealthStudy(50).Inthisprospective cohortstudyoI35988olderwomeninIowa,USA,initiallyIreeoIdiabetes,whowere Iollowed Ior six years, multivariate-adjusted relative risks (RR) oI diabetes were 1.0, 1.09, 1.00, 0.94, and 0.78 across quintiles oI total dietary Iibre intake (p-value Ior trend 0.01).Stronger associations Ior cereal Iibre as compared to Iruit and vegetable Iibre sources were also Iound. More recently,two largeprospectivecohort studies havealso reported inverse associations between dietary cereal Iibre intake and risk oI developing type 2 diabetes (51, 52).UsingdataIromtheAtherosclerosisRiskinCommunitiesstudy,Stevensand colleagues Iailed to Iind an association between Iibre Irom Iruit and vegetable sources and 12 diabetesriskamong12251Americanadultsaged45-64years;onlyIibreIromcereal grainswasassociatedwithlowerriskoIdiabetes(51).ResearchersinFinlandIoundan associationbetweenintakeoIdietaryIibreIromcerealgrainsanddevelopmentoItype2 diabetes among 2286 men and 2030 women Iollowed Ior 10 years but they did not examine the relationship oI dietary Iibe Irom Iruit or vegetable sources and type 2 diabetes (52). It is important to note that most iI not all oI these studies adjusted Ior the eIIects oI body mass index (BMI) and other Iactors which might have obscured an independent eIIect oI dietary Iibre on thedevelopment oI type2 diabetes.Nevertheless, Iibre increases satiety, reduces hunger, and decreases energy intake and hence contributes to weight control and avoidance oIobesity(53).GiventhatobesityisarguablythemostpotentriskIactorinthe developmentoItype2diabetes,theeIIectsoIdietaryIibreduetoitsroleinweight management were overlooked in most iI not all oI these investigations. Several prospective studies have identiIied a signiIicant inverse association between dietaryIibreintakeandriskoIcoronaryheartdisease(54-59).Asmentionedabove, dietaryIibrebluntsthebody`sinsulinemicresponsetocarbohydrates(44).Experimental studieshavealsoshownthathigherlevelsoIinsulinmaypromotedyslipidemia, hypertension, abnormalities in blood-clotting Iactors, and atherosclerosis (60).In addition, water-solubledietaryIibrehasbeenshowntodecreasebothtotalandlow-density lipoprotein(LDL)cholesterolwhilenotaIIectinglevelsoIhigh-densitylipoprotein cholesterol (61).While the cholesterol-lowering eIIects oI dietary Iibre are usually thought tobemodest,theymayplayaroleintheinverseassociationbetweenintakeoIIibreand riskoICVDs.Moreover,recentstudieshavesuggestedinverseassociationsbetween dietary Iibre and other CVD riskIactors suchasblood pressure,waist-to-hipratio, Iasting blood insulin concentration, 2-h post-glucose blood insulin concentration, concentrations oI triglyceridesandoIIibrinogen(45).DietaryIibreisalsoassociatedwithlowerblood pressureinobservationalstudies(62).Inrandomizedcontrolledtrials,dietaryIibre supplementation has been shown to reduce blood pressure by small but signiIicant amounts (63). 3.2 C|ycaem|c Load 13 AnotherimportantIunctionalaspectoIwholeIruitsandvegetablesistheirlowglycaemic index and glycaemic load (64). The glycaemic index oI a Iood compares the glucose-raising potentialoIequalamountsoIcarbohydratebutitdoesnotcapturethequantityoI carbohydrateinaIoodserving.Theglycaemicload,theproductoItheglycaemicindex value oI a Ioodand its total carbohydrate content, captures both aspectsoI theglucogenic potential oI a Iood (65). Since the introduction oIthe glycaemic index in 1981, the role oI carbohydrates in the development oI type 2 diabetes has been thought to depend less on the size and structure oI the molecules and more on the body`s glycaemic response to diIIerent carbohydrates(66).Forexample,whilethecarbohydrateincarrotshasahighglycaemic index, a carrot contains a relatively small amount oI carbohydrate, so the Iood as a whole, has a moderate glycaemic load. AdietwithalowglycaemicindexhasbeenassociatedwithlowerrisksoItype2 diabetesandcoronaryheartdiseaseinprospectivestudies(65,67).InIeedingtrialsoI humans,alowglycaemicindexdiethasalsobeenassociatedwithprolongedsatiety responses(68,69)whichmayIurtheraidinweightcontrol.ArecentreviewidentiIiedat least15studiesdemonstratingincreasedsatiety,delayedreturnoIhunger,ordecreased Iood intake aIter consumption oI Ioods with a low, rather than high, glycaemic index (68).TherichIibrecontentoIwholeIruitsandvegetablesmaybepartlyresponsibleIorthis response, but other Iactorssuch as the physical structure oI Iruits andvegetables and their content oI enzyme inhibitors may also play an important role. FewepidemiologicstudieshaveexamineddirectlytheroleoItypeandamountoI carbohydrateinrelationshiptothedevelopmentoIhyperglycaemiaortype2diabetes. Thosewhichhave,generallyIoundlittleassociationbetweentotalcarbohydrateintakeor intakeoIsimplesugarsandthedevelopmentoIdiabetes(46,50,70-73).Oneexception, the Iowa Women`s Health Study, Iound that intake oI glucose or Iructose was signiIicantly and positively related to the risk oI developing type 2 diabetes (50).Severallargeprospectivecohortstudieshaveexaminedtherelationshipbetween glycaemicindexorloadandriskoIdevelopingtype2diabetes(46,47,50,74).Onthe whole, people with diets in the highest range oI glycaemic index or load were signiIicantly morelikelytodeveloptype2diabetesthanthosewithdietsinthelowestranges.For example,inthe NursesHealthStudy(47), the RR oIdeveloping type 2diabeteswas1.47 14 (95 conIidence interval (CI), 1.161.86) comparing the highest and the lowest quintile oI dietaryglycaemicload.Similarly,intheHealthProIessionalsFollow-upStudy(46),the RRoIdevelopingtype2diabeteswas1.37(95CI,1.021.83)comparingtheextreme quintilesoIdietaryglycaemicload.However,twolargeprospectivestudiesIoundno relationship between dietary glycaemic index or glycaemic load and risk oI developing type 2 diabetes (50, 51).This lack oI association mayhave been related to the methods oI diet assessmentused.Onthewhole,theevidencesuggeststhatthereplacementoIhigh glycaemicindexIoodsinthedietbyIruitandvegetablesmayhaveawiderangeoI beneIicialpublichealthconsequences,includingreducedrisksoIobesity,coronaryheart disease and development oI type 2 diabetes. 3.3 Fructose FructoseisunlikelytobeoneoIthenutrientsinIruitandvegetablesthatcontributes signiIicantly to their protective eIIects; however it does bear discussion given recent studies oI its relationship to chronic disease. In the 1970s Iructose, particularly in the Iorm oI high-Iructose syrup manuIactured Irom starch, began to be used as a replacement Ior sucrose in beveragesandbakedgoods.TodaythemajorityoIIructoseconsumedisintheIormoI high-Iructose corn syrup (75).Sorbitol and mannitol are used in a variety oI Iood products becausetheyhaveIewercaloriespergramthandoeithersucroseorIructose;intheliver theyarereadilyconvertedtoIructose.FructosebypassesthephosphoIructokinase regulatorystepoIglycolysis,inwhichglucosecanbeconvertedtoglycogenratherthan enteringtheglycolytic pathway. Asaresult, Iructoseincreases hepaticpyruvate and lactic acid production, activates pyruvate dehydrogenase, and shiIts the balance Irom oxidation to esteriIication oI Iatty acids, which can increase very-low-density lipoprotein synthesis (76). In addition, Iructose stimulates less insulin secretion Irom pancreatic beta cells and causes a lesserriseinpostprandialinsulinconcentrationsthanglucose-containingcarbohydrates. Leptinisregulatedbyinsulinresponsestomeals,henceloweringcirculatingleptinand insulininindividualswhoconsumehighIructosedietscouldincreasethelikelihoodoI weightgainanditsassociatedmetabolicsequelae(77).InIeedingstudies,theeIIectsoI Iructose on plasma triglyceride levels have been Iound to be inconsistent. This may be due 15 toIactorssuchastheamountoIIructoseconsumed,energybalance,andbaseline triglyceride,insulin,andglucoselevels(78).Thepostprandialriseintriglyceridelevels aIterIatintakemaybeaugmentedwiththeadditionoIIructosetoatestmeal(79). However, a study in individuals with type 2 diabetes showed a lack oI signiIicant variation inglucose,lipid,andinsulinresponsestothree28-dayisocaloricIeedingperiodswhen 20 oI calories were either Iructose, sucrose, or starch (80). Fructose in Iruit and vegetables is unlikely to cause any oI the disturbances in lipid orbloodglucosedescribedabove.ThisisbecauseaccompanyingnutrientssuchasIibre, phytochemicals and antioxidants are delivered in conjunction with Iructose in the Iorm oI a wholeIruitorvegetable.FormostindividualsconsumingIructoseinwholeIruitsand vegetables rather than Iructose-sweetened baked goods and beverages, postprandial rises in glucosemaybeblunted,andinsulinlevelsmayremainmoreconstantthanaIter consumption oI other sugars. 3.4 Fo|ate FolicacidandvitaminB12areimportantIorthemetabolismoIhomocysteine.Dietary intakeoIIolatehasbeenshowntobeinverselyassociatedwithplasmaconcentrationsoI homocysteine(81)andelevatedhomocysteineconcentrationshavebeenrelatedtoan increasedCVDrisk(82,83).Moreover,IolateitselImayhavevasculo-protectiveeIIects (84). In a randomized trial, supplementation oI the diet with Iolic acid and vitamin B6 was showntoreducemarkersoIendothelialdysIunctionandtheprogressionoIsubclinical atherosclerosis(85).BothdietaryandserumIolateconcentrationshavebeeninversely associatedwithmortalityIromCVD(86-89).Morerecently,aninverseassociation betweendietaryIolateintakeandstrokeincidencewasdemonstratedinarepresentative sample oI the adult population in the USA (90). Thus, increased Iolic acid intake may be an importantaspectoItheapparentprotectiveeIIectagainstCVDsoIahighintakeoIIruits and vegetables. 3.5 Ant|ox|dants 16 AntioxidantsaresubstancesthatinactivatereactiveoxygenspeciesandthereIore signiIicantlydelayorpreventoxidativedamage.Atherosclerosisisthoughttoproceedin partduetotheoxidationoIlipidsinplaqueIormation.Fruits,includingberries,and vegetablesarerichsourcesoIantioxidantssuchasvitaminE,vitaminC,polyphenols, Ilavonoids,andcarotenoidswhichmayhelppreventatherosclerosisandsubsequent ischaemic heart diseases.However, dietary supplements oI speciIic antioxidants, including vitamins C, E, and beta-carotene, when tested in randomized controlled trials did not on the whole show signiIicant beneIit in secondary prevention oI CVDs (91). Recently,otherantioxidantcompoundssuchaslycopeneandIlavonoidshave receivedIurtherattention(21,92,93).Dietarylycopene,whichisderivedinlargepart Iromtomatoproducts,wassigniIicantlyandinverselyassociatedwithRRoICVDsina cohortoI39876middle-agedwomen(94).FlavonoidintakewasmeasuredbyYochum and colleagues in 34 492 postmenopausal women in Iowa, USA.AIter 10 years oI Iollow-up, participants in the highest quintile oI Ilavonoid intake had the lowest risk oI death Irom ischaemic heart disease (93). Berriesareparticularlyrichinphenoliccompounds,andplayanimportantrolein Iruitconsumptioninmanycountries.PolyphenoliccompoundsIrompomegranatejuice havebeenshowntoinhibitLDLcholesterolperoxidation,andadditionoIpomegranate juicetothedietIedtoatheroscleroticmicehasbeenshowntoinhibitsignIicantlythe development oI plaques and streaks in these animals (21).Some research suggests that antioxidants may protect against diabetes mellitus (95-99). Vitamin C intake has been inversely related to the incidence oI diabetes and impaired glucosetoleranceinacohortstudy(100).OnestudyshowedthatintakeoIvitaminE, commonlyIoundinvegetableandseedoils,wasinverselyrelatedtotheincidenceoI diabetesmellitus(101)butanotherstudyIailedtoIindasigniIicantassociationaIter adjustment Ior various risk Iactors (102). Antioxidants ingested in whole Ioods such as Iruit andvegetablesandinjuicesmayactincombinationwitheachotherand/orother phytochemicals within the Ioods to provide their protective eIIects. 3. Potass|um 17 Potassium may play an important role in the eIIect that Iruit and vegetable consumption has on the incidence oI, and mortality Irom, CVDs.Epidemiological studies have identiIied an inverseassociationbetweendietaryintakeoIpotassiumandbloodpressurewithinand acrosspopulations(103).Inaddition,randomizedcontrolledtrialshaveshownthat potassiumsupplementationlowersbloodpressureinbothhypertensiveandnormotensive persons(104).Conversely,alowdietarypotassiumintakehasbeenassociatedwith elevatedbloodpressure.Inarandomized,cross-overtrialoIpotassiumdepletionin10 normotensivemen,thoseIedalowpotassiumdiet(10mmol/day)hadsigniIicantly increasedmeanarterialbloodpressure(4mmHgincrease,p0.05)(105).Inasecond randomized,cross-overtrialoIdietarypotassiumdepletion(potassiumconsumptionIrom 96mmol/dayto16mmol/day)in12hypertensivesubjects,thesameresearchgroup reported signiIicant increases in blood pressure, both systolic (7 mmHg increase, p 0.01) anddiastolic(6mmHgincrease,p0.04),aIterthelowpotassiumdiet(106).Such evidence suggests that a diet rich in Iruit and vegetables and hence high in potassium may protect against increased risk oI stroke through lowering blood pressure.Severalstudieshavereportedaninverserelationshipbetweenpotassiumintakein thedietandriskoIstrokeorCVDs.Xieandcolleaguesconductedanecologicanalysis whichindicatedaninverserelationshipbetween24-hurinaryexcretionoIpotassiumand strokemortalityamong27populationgroups(107).InapopulationoI859maleand IemaleretireesinsouthernCaliIornia,USA,KhawandBarrett-ConneridentiIiedastrong inverseassociationbetweenpotassiumintakeandstrokemortality(108).Ascherioand colleaguesalsodocumentedaninverserelationshipbetweentheriskoIstrokeanddietary potassiumintakeinacohortoI43738malehealthproIessionals(109).IntheNational HealthandNutritionExaminationSurveyEpidemiologicFollow-upStudy(NHEFS), dietarypotassiumwasinverselyassociatedwithriskoIstrokeaIteradjustmentIor established CVD risk Iactors (110). 3.7 Hagnes|um Fruit and vegetables are also rich in micronutrients and minerals such as magnesium, which may lower the risk oI developing diabetes mellitus (46, 71). Magnesium plays an important 18 roleininsulinaction,andhypomagnesaemiaiswellrecognizedinpersonswithdiabetes (111).Hypomagnesaemiamayimpairinsulinsecretionandpromoteinsulinresistancein thediabeticpatient(112).Inaddition,magnesiumintakeandbloodconcentrationsoI magnesium have been Iound to be inversely related to insulin concentrations in population-based studies (50, 113, 114). 19 3.8 8ummary of potent|a| mechan|sms In summary, while each oI the components described in the sections above may play a role in protecting against CVDs, it is their combined eIIects that are seen in a diet rich in whole Iruitsandvegetables.ThebiochemicalcomplexityoIIruitandvegetablesasdelivery systemsIorprotectivenutrientsandIunctionalcomponentsshouldnotbeunderestimated.Hence, in any dietary recommendation to prevent CVDs and type 2 diabetes it is important to emphasize the consumption oI whole Iruits and vegetables rather than speciIic nutrients or supplements. 4.Effects of fru|t and vegetab|e |ntake on r|sk factors for 6V0 and d|abetes 4.1 0bes|ty The potential role oI Iruit and vegetables in the management oI obesity has been reviewed brieIlyaboveandmorethoroughlyinacompanionmanuscript.Obesityhasincreasedto epidemicproportionsworldwidewithmorethan1billionadultsclassiIiedasoverweight, andatleast300millionoItheseobeseasdeIinedbyaBMIscoreoI30ormore(115). ObesityisoneoIthemostprevalentriskIactorsIorchronicdiseasessuchasCVDs (includingbothstrokeandischaemicheartdisease)anddiabetes,andhaslongbeen recognized as one oI the strongest risk Iactors Ior the development oI type 2 diabetes. It has been estimated to account Ior 60 to 90 oI the variance (116, 117). SeveralprospectivestudiesinwidelydiIIerentpopulationshavedemonstrateda strongly positive association between BMI, weight gain and the subsequent development oI type2diabetes(118).ColditzandcolleaguesIoundthattheriskoItype2diabeteswas increased nearly 90-Iold among Iemale nurses who were morbidly obese (BMI35) at 30 to 55 years oI age but oI normal weight (BMI 22) at 18 years oI age(118). In addition, manystudieshavedemonstratedthatweightlossimprovesglycaemiccontrolindiabetic individuals and can lead to aremissionoIdiabetes in a Iew (119-121).Studies examining the eIIects oI energy-restricted diets in people with type 2 diabetes have shown that Iasting 20 hyperglycaemia declines rapidly within the Iirst week and is accompanied by reductions in hepaticglucoseproduction,evenbeIoresigniIicantweightlossoccurs(122,123). Anderson and colleagues combined the results oI 10 studies oI obese type 2 diabetics who weretreatedIorIourtosixweekswithverylow-energydiets(121).OverthecourseoI these studies, subjects lost approximately 10 oI their body weight and their Iasting plasma glucosevaluesdecreasedbyabouthalIaItertwoweeksandremainedthereIorthe remainderoItheobservationperiod.However,weightlossonthesedietswasoItennot sustained and the quality oI glycaemic control decreased as weight was regained.More recent prospective studies oI sustained weight loss and development oI type 2 diabetessuggestthatevenmodestweightlossisassociatedwithasigniIicantlyreduced diabetesrisk(124,125).ThistypeoIevidencesuggeststhatobesityandexcessenergy consumptionare perhaps themost importantcontributing Iactors to the risk oI developing type 2 diabetes. Thus, evenminor weight reductions may havemajor beneIicialeIIectson subsequent diabetes risk in overweight individuals. 4.2L|p|ds Fruit,vegetables,andlegumeshavebeenshowntodecreaseLDLcholesterol concentrations in humans. In the Dietary Approaches to Stop Hypertension (DASH) trial, a diethighinIruitandvegetableswasassociatedwithareductioninLDLcholesterol comparedtoacontroldiet.HowevertheassociationdidnotreachstandardlevelsoI statisticalsigniIicance(126).IntheIndianDietHeartStudy,Iruitandvegetable consumptiondecreasedLDLcholesterolconcentrationsbyapproximately7(127).Ina randomized trial among persons who had suIIered acute myocardial inIarction, a reduction in LDL cholesterol was shown to occur aIter 12 weeks oI Iruit and vegetable intake (128). More recently, in the US National Heart, Lung, and Blood Institute Family Heart study, the consumptionoIIruitsandvegetableswasinverselyrelatedtoLDLcholesterol concentrationsinmenandwomen(129).Beans,peas,andotherlegumeshavealsobeen showntolowercholesterollevels.Inameta-analysisoI29clinicaltrials(130)soybean proteinhasbeenshowntoreducetotalandLDLcholesterolconcentrationsinserum.Legumeintakeotherthansoybeanhasalsobeenassociatedwithareductioninserum 21 cholesterol in clinical studies (131-136).A meta-analysis oI 11 clinical trials examining the eIIects oI legumes other than soybeans demonstrated a 7.2 reduction in total cholesterol, 6.2 reduction in LDL cholesterol, and a 16.6 reduction in triglycerides with no eIIect on HDLcholesterol(137).LegumesareasigniIicantsourceoIsolubleIibrewhichmaybe partiallyresponsibleIortheircholesterol-loweringeIIects.OnehalIcupoIcookedbeans containsonaverage6gtotalIibreand2gsolubleIibre,whichisthesameamountoI solubleIibre and more total Iibre than that containedin one third oIa cup oI dry oat bran (138).OtherconstituentsoIlegumesincludingoligosaccharides,isoIlavones, phospholipids, saponins, and known and unknown phytochemicals may also be part oI the cholesterol-lowering eIIects oI these Ioods (137). 4.3 hypertens|on DietarymodiIicationhaslongbeenknowntoaidinthecontroloIhypertension,andIruit and vegetable intake in particular hasbeen shown to reduce blood pressure in a variety oI settings,includingrandomizedcontrolledtrials(139-141).Severaldecadesago,itwas noted that people on vegetarian diets had consistently lower blood pressure than those with omnivorousdiets(142).In trialsoIvegetariandiets,replacinganimalproductswith vegetable productsreducedbloodpressureinnormotensiveandhypertensive adults(139, 141). However, Iewerinvestigations have speciIicallyexaminedwhole Iruit and vegetable intake and hypertension. A recentreport oI 1710 men, aged 4157yearsand IollowedIor 40 years, demonstrated that intake oI Iruit and vegetables was inversely associated with an age-related rise in blood pressure over the course oI the study (143). The recent randomized controlled DASH trial showed that a diet supplemented with Iruit and vegetables lowered blood pressure in a multiethnic population.In the study, 459 adults with systolic blood pressure 160 mmHg and diastolic blood pressure 8095 mmHg were randomly assigned to receive the control diet, a diet rich in Iruit and vegetables, or a combination diet rich in Iruit, vegetables, and low-Iat dairy products with reduced saturated andtotalIat,Ioreightweeks(140).Sodiumintakeandbodyweightweremaintainedat constant levels. The Iruit and vegetable diet reduced systolic blood pressure by 2.8 mmHg (p 0.001) and diastolic blood pressure by 1.1mmHg (p 0.07) compared tothe control 22 diet.Thecombinationdietresultedinevengreaterreductionsinsystolicanddiastolic blood pressures. Singh and colleagues conducted a randomized controlled trial examining the eIIects oI supplementingguavaIruitinthedietoI72participants(144).TheyIoundasigniIicant decrease in mean systolic and diastolic pressures (7.5/8.5 mmHg net decrease, respectively) amongparticipantsontheguava-supplementeddiet.Severalstudieshavecombined increases in Iruit and vegetables with other dietary interventions, weight loss, and increases inphysicalactivity,thusobscuringthespeciIiceIIectsoIIruitandvegetableintakeon blood pressure (145). 5.Fru|t and vegetab|e |ntake and r|sk of 6V0 - rev|ew of prospect|ve stud|es 5.1 8earch strategy and |nc|us|on cr|ter|a for ||terature rev|ew ThisreviewIocusesonprospectiveevidenceincludingthosecohortstudiesreviewed previously. Data Irom prospective cohort studies have the advantage oI temporality in long periodsoIIollow-up,andsuIIerlessIrominIormationbiasthanthatoIcasecontrol studies.Thisreviewsetouttoincludeallindividuallevel,prospectivestudieswherethe primaryoutcomewasdocumentedCVDs(speciIically,ischaemicheartdiseaseorstroke) andexposurewasaIruitorvegetableintakeasawholeIoodorIoodgroupratherthana biomarker or nutrient. Studies oI total mortality or mortality due to CVD other than stroke or ischaemic heart disease were not included. Studies oI adults oI both sexes were included. ChildrenwereexcludedasdocumentedCVDIromatheroscleroticmechanismsisrarein this population except in those with genetic deIects oI metabolism.InordertoidentiIyprospectivestudiesoIIruitandvegetableintakeandCVD,a MEDLINEsearchwasconductedusingtheMeSHterms'vegetablesand'Iruitto identiIystudiesthatmappedtoeitheroIthesesubjectheadingswithexplodedIocus,and combined these with the term 'cardiovascular diseases also with exploded Iocus to include allsubheadings.ThesearcheswerelimitedtohumanstudiespublishedinEnglish.This strategy yielded 296 reIerences which were then evaluated Ior inclusion. 23 StudieswereincludediItheywereprospectiveandreportedameasureoI association(standardizedmortalityratio,RR,oddsratio(OR),orhazardratio)between wholeIoodintake(ratherthanbiomarkerornutrientintake)andCVD.Whenstudies meetingthesecriteriawereidentiIied,theirbibliographieswerealsosearched,andother articles which appeared appropriate Ior this review were obtained.Table 1 summarizes the availableprospectivestudieswhichexaminetherelationshipbetweenIruitandvegetable consumptionaswholeIoodsandriskoIischaemicheartdisease.Table2summarizesthe available prospective studies oI Iruit and vegetable consumption in relation to stroke. 5.2 Prev|ous rev|ews Onthewhole,ecologicandcasecontrolstudiesIocusingonIruitandvegetable consumptioninrelationtoCVDriskinnon-vegetarianpopulationshaveconsistently showninverseassociations(146-155).TheevidenceregardingIruitandvegetableintake andCVDhasbeenreviewedpreviouslybyNessandPowlesin1997(155),andthat regarding Iruitand vegetable intake and stroke was reviewed by the same authors in 1999 (156).Subsequently,severallargeprospectivecohortstudieshavealsoidentiIiedan inverseassociationbetweenintakeoIIruitandvegetablesandCVD.In1997,Nessand Powles (155) identiIied only Iive prospective studies (19, 157-161) that examined Iruit and vegetableintakeaswholeIoodsratherthannutrients(e.g.IibreIromIruitorvegetable sources, vitamin C) or phytochemicals (e.g. carotenoids, Ilavonoids) in relation to CVD. OI those,threeshowedsigniIicantinverseassociations(19,157-159),whiletheothertwo (160, 161) showed no signiIicant association. Small samplesizesand low event rates may partially explain these inconsistent Iindings. 5.3 Prospect|ve ev|dence SincethereviewbyNessandPowles(155),nineprospectivecohortstudieshavebeen conducted relating intake oI Iruit and vegetables to ischaemic heart disease.OI those, Iour IoundsigniIicantinverseassociations(162-165),whileIiveIoundinverseassociations which tended toward, but did not reach, statistical signiIicance aIter appropriate adjustment 24 (18,93,166-168).EightprospectivecohortstudiesevaluatingintakeoIIruitand vegetablesandriskoIstrokehavebeenconductedsincethereviewbyNessandPowles (156), and oI these, Iive Iound signiIicant inverse relationships between Iruit and vegetable consumptionandriskoIstroke(162,169-172),andthreehadinverseIindingsthattended toward signiIicance (18, 173, 174). InastudyoI4336maleand6435IemaleparticipantsintheUnitedKingdom recruitedthroughhealthIoodshops,vegetariansocietiesandmagazines,Keyand colleagues Iound that the daily consumption oI Iresh Iruit was associated with signiIicantly reduced mortality Irom ischaemic heart disease (RR, 0.76; 95 CI, 0.600.97), stoke (RR, 0.68;95CI,0.470.98),andIorcausescombined(RR,0.79;95CI,0.700.90),aIter adjustment Ior smoking (175).Participants in this study were Iollowed Ior an average oI 17 years and 43 were vegetarian.ResultsIromtheNursesHealthStudyandHealthProIessionalsFollow-upStudy showed a 31 lower risk (RR, 0.69; 95 CI, 0.520.92) oI ischaemic stroke Ior persons in the highest quintile oI Iruit and vegetable intake (median 9.2 servings per day among men, 10.2servingsperdayamongwomen)comparedtothoseinthelowestquintileoIintake (median2.6servingsperdayamongmen,2.9servingsperdayamongwomen)aIter adjustmentIorage,smoking,alcohol,IamilyhistoryoImyocardialinIarction,BMI, supplementuse, physical activity,hypertension, hypercholesterolemia, total energyintake, and among women, postmenopausal hormone use (169).A signiIicant inverse relationship was also Iound Ior coronary heart disease, with a 20 lower risk (RR, 0.80;95 CI, 0.690.93)IorcoronaryheartdiseaseseenamongpersonsinthehighestquintileoIIruitand vegetableintakeascomparedwiththoseinthelowest(165).Thiswasawell-designed studywithaverylargesamplesizeandrepeatedmeasuresoIvalidated,semi-quantitative dietaryassessment.Inaddition,participantsgenerallyconsumedalargenumberoI servings oI Iruit and vegetables per day and there was a wide range in their dietary habits.In a study oI 730 men born in 1913 and Iollowed in later liIe Ior 16 years, Irequent Iruit,butnotvegetable,consumption(67timesperweek)wasassociatedwith signiIicantlylowerriskoItotalmortality(RR,0.87;95CI,0.760.96)thaninIrequent Iruitconsumption(01timeperweek)aIteradjustmentIorsmoking,hypertension,and serumcholesterolconcentrations(176).CVDmortalitywaslowerinthegroupwithmore 25 IrequentconsumptionoIIruitandvegetablesinunivariateanalyses;howeverthe relationshipwasnotstatisticallysigniIicantaItermultivariateadjustment.Itshouldbe notedthatIoodhabitswereassessedwithaFFQatbaselineandwerenotupdatedduring the study. Also, the very small sample size may have limited the power oI the study. AstudyoI9608maleandIemaleparticipantsintheNFEHSIollowedIoran averageoI19yearsIoundanindependentinverseassociationbetweenIrequencyoIIruit and vegetable intake and risk oI CVDs (162).Fruit and vegetable intake at least three times perdaycomparedwithlessthanonceperdaywasassociatedwitha27lowerriskoI stroke(RR,0.73;95CI,0.570.95;p-valueIortrend0.01),a42lowerstroke mortality (RR, 0.58; 95 CI, 0.331.02; p-value Ior trend 0.05), a 24 lower ischaemic heartdiseasemortality(RR,0.76;95CI,0.561.03;p-valueIortrend0.07),a27 lower CVD mortality (RR, 0.73; 95 CI, 0.580.92; p-value Ior trend 0.008), and a 15 lowerall-causemortality(RR,0.85;95CI,0.721.00;p-valueIortrend0.02),aIter adjustmentIorestablishedCVDriskIactorsincludingage,sex,ethnicity,education, smoking status, regular alcohol intake, physical activity, diabetes, hypertension, and serum cholesterollevels.Howeverthisstudyusedasingle24-hrecallwhichislesslikelytobe representative oI usual Iruit and vegetable intake, and lacked portion size inIormation.IntheWomen`sHealthStudyoI39876IemalehealthproIessionals,inwomenin thehighestquintileoIIruitandvegetableintake(medianservings/day10.2)theRRoI CVD was 0.68 (95 CI, 0.510.92; p-value Ior trend 0.01), and oI myocardial inIarction was0.47(95CI,0.280.79;p-valueIortrend0.004),aIteradjustmentIorage, smoking,andrandomizedtreatmentstatus(167).TherewasasigniIicantlineartrend acrossquintilesindicatingadoseresponserelationshipIorincreasingIruitandvegetable intake.However,IurtheradjustmentIorknownCVDriskIactorsincludingdiabetes, hypertension, and serum cholesterol among others, attenuated the statistical signiIicance oI the RR estimates. AmongacohortoI15220menenrolledinthePhysiciansHealthStudy,a randomizedcontrolledtrialoIaspirinandbeta-caroteneinthepreventionoICVD, participants who consumed at least 2.5 servings per day oI vegetables (mainly green leaIy) had a 23lower risk oI coronary heart disease(RR,0.77; 95CI, 0.600.98) thanthose consuminglessthanoneservingperday,aIteradjustmentIorage,randomizedtreatment, 26 BMI,tobaccouse,alcoholintake,physicalactivity,diabetes,hypertension, hypercholesterolaemia,anduseoImultivitamins(164).DesignlimitationsoIthestudy prevented the examination oI Iruit intake and CVD in this cohort. AnexaminationoItheseasonalconsumptionoIsaladvegetablesandIreshIruitin relationtothedevelopmentoICVDin1489menand1900womenaged3575years IollowedIorsixyearsintheUnitedKingdomIoundaprotectiveroleIorIrequentsalad vegetableconsumptionatanyseasonamongwomen(ORwinter0.76,95CI0.650.89; OR summer 0.76, 95 CI 0.650.89) and Irequent Iruit consumption in women (OR winter 0.84,95CI0.740.94;ORsummer0.85,95CI0.740.97)(163).Amongmen, Irequent winter salad vegetable consumption was more closely protective than summer (OR winter0.85,95CI0.721.00;ORsummer0.95,95CI0.821.10).Therewasno protectiveassociationIorIruitconsumptioninmen.Thismaybeduetothesmaller amounts oI Iruit consumed by men than women.RissanenandcolleaguesevaluatedtherelationshipbetweenIruitandvegetable intake and CVDs among 2641 men in Finland aged 4260 years who were Iollowed Ior an average oI 13 years (168). AIter adjustment Ior major CVD risk Iactors, the RR oI all-cause mortalityandCVD-relatedmortalityIorparticipantsinthehighestquintileoIIruit,berry andvegetableintakewas0.66(95CI,0.500.88)and0.59(95CI,0.331.06) respectively, compared with men in the lowest quintile. UsingdataIromtheARICstudyoI15792menandwomenintheUSAIollowed Ior11years,SteIIenandcolleaguesIoundastronginverseassociationbetweenIruitand vegetableintakeandall-causemortality(18).RRs(95CI)oImortalityIorquintilesoI Iruitandvegetableintakewere1.08(0.881.33),0.94(0.751.17),0.87(0.681.10),and 0.78 (0.611.01), respectively; p Ior trend 0.02.An inverse association between Iruit and vegetable intake and CVD was observed amongAIricanAmericans but not among whites (p-value 0.01). In this study, the risk oI ischaemic stroke was not signiIicantly related to Iruitandvegetableconsumption.Onaverage,intakeoIIruitandvegetableswashigher amongnurses,malehealthproIessionalsandmenintheFraminghamstudies(19),alloI whichshowedinverseassociationswithischaemicstroke,thanamongparticipantsinthe ARIC study. In addition, potato was included as a vegetable in the ARIC study. 27 5.4 Potent|a| |mpact of |ncreased fru|t and vegetab|e |ntake on 6V0 r|sk Takenasa whole, thesedata support the hypothesisthat Iruitand vegetables may playan important role in dietary strategies Ior the prevention oI ischaemic heart disease and stroke. RecentestimatesoIthepotentialcontributionoIincreasedIruitandvegetableintaketo health gain in various countries have ranged Irom 8000 CVD deaths prevented annually in thepopulationoItheNetherlands(177)to26000deathsbeIoretheageoI65years annuallyintheEuropeanUnionasawhole(in2001)(178).Acrossstudies,theriskoI ischaemicheart disease is about 15 lower at the 90th thanthe10thpercentile oI Iruit and vegetable consumption (179).Figure 1 shows a summary measure oI the recent studies oI IruitandvegetableintakeandriskoIischaemicheartdisease.Figure2showsasummary measure oI studies examining the association between Iruit and vegetable intake and risk oI stroke.28 .Fru|tandvegetab|e|ntakeandr|skofd|abetesme|||tus-rev|ewof ep|dem|o|og|ca| stud|es .1 8earch strategy and |nc|us|on cr|ter|a The same search criteria describedIor identiIicationoIstudies relating Iruit and vegetable intakeandCVDswereadaptedIoruseinidentiIyingstudiesrelatingtodiabetes.No emphasis was placed on identiIying prospective studies regarding diabetes; the aim was to includeallindividuallevelstudies(cross-sectional,casecontrol,prospectivecohort studies)wheretheprimaryoutcomewasdiabetesmellitus,glycosylatedhaemoglobinor bloodglucose,andexposurewasIruitorvegetableintakeasawholeIoodorIoodgroup rather than biomarker or nutrient.In order to identiIy studies oI Iruit and vegetable intake anddiabetesmellitus,aMEDLINEsearchwasconductedusingtheMeSHterms 'vegetables and 'Iruit to identiIy studies that mapped to either oI these subject headings withexplodedIocus,andcombinedthesewiththeterm'diabetesmellitusalsowith explodedIocustoincludeallsubheadings.Thesearcheswerelimitedtohumanstudies publishedinEnglish.Thisstrategyyielded62reIerenceswhichwerethenevaluatedIor inclusion. StudieswereincludediItheyreportedameasureoIassociation(standardized mortality ratio, RR, OR, beta coeIIicient) between whole Iood intake, rather than biomarker ornutrientintake,anddiabetesmellitus,glycosylatedhaemoglobin,orbloodglucose. StudiesoIchildrenwereexcluded.WhenstudiesmeetingthesecriteriawereidentiIied, their bibliographies were also searched, and other articles which appeared appropriate were obtained Ior this review. 29 .2 Ep|dem|o|og|ca| ev|dence A small but growing body oI evidence links a diet rich in Iruit and vegetables with a lower riskoIdevelopingtype2diabetesmellitus.ThislinkwasIirstnotedamongvegetarians. SnowdonandcolleaguesexamineddietinrelationtodiabetesamongapopulationoI25 698adultSeventh-dayAdventists.Inthispopulation,vegetarianswerehalIaslikelyas omnivorestodevelopdiabetesoverthecourseoI21years`Iollow-up(180).Fruitand vegetable intake was subsequently associated with lower risks oI diabetes in non-vegetarian populations as well. Table 3 lists the studies oI this association identiIied and discussed in this literature review.Severalcross-sectionalstudieshavesuggestedthatahigherintakeoIIruitand vegetablesprotectsagainstdevelopmentoIdiabetes.Apopulation-basedstudyinthe United Kingdom examined the association between Iruit and vegetable intake and abnormal glucose tolerance in 1122 middle-aged men and women without known diabetes (181). All participantsunderwentaglucosetolerancetestandhadtheirIoodconsumptionassessed usingaFFQ.Non-obeseparticipantswhoreportedIrequentintakeoIsaladandraw vegetablesthroughouttheyearhadsigniIicantlylowerprevalenceoItype2diabetesand abnormalglucosetolerancetestresultsthanthosewhoreportedinIrequentconsumption (OR,0.18;95CI,0.040.81)aIteradjustmentIorage,sex,andIamilyhistory. Associations with Iruit consumption were not signiIicant in this study. However in another cross-sectionalstudyoI5996middle-agedparticipantsnotknowntohavediabetes, Sargeantetal.observedadirectassociationbetweenIruitandvegetableconsumptionand concentrationsoIglycosylatedhaemoglobin(17).ParticipantswhoreportedIrequent consumptionoIIruitandgreenleaIyvegetableshadsigniIicantlylowermeanpercent glycosylatedhaemoglobinconcentrations(5.34;standarderror(se),0.01)thantheir counterpartswhoreportedseldomorneverconsumingtheseIoods(5.41;se,0.03;p 0.046)aIteradjustmentIorage,sex,BMI,waisthipratio,energyintake,Iamilyhistory, tobaccouse,alcoholintake,education,physicalactivity,supplementuse,andvegetarian diet.TherelationshipremainedsigniIicantaIterIurtheradjustmentIordietaryintakeand plasmaconcentrationoIvitaminC,saturatedIatintake,andIibreintake.Similarresults were Iound among patients with type 1 diabetes.30 Fewer prospective studies have directly related intake oI Iruit and vegetables to risk oItype2diabetes.InacohortoI338EuropeanmenIollowedIor30years,higher consumptionoIvegetablesandlegumeswasinverselyassociatedwithimpairedglucose tolerance,assubstantiatedby2-hbloodglucoseconcentration(100).Howevertheresults wereobtainedusingmultivariatelinearregressiontopredict2-hpost-loadglucoserather than a RR oI diabetes.Hence these results are less readily comparable to other studies. ResultsIromtheNursesHealthStudyshowedaninverserelationshipbetween intake oI vegetables and development oI diabetes, but no association with Iruit (71).Non-obesewomen(BMI_29)inthehighestquintileoIvegetableintake(2.9servingsper day)hada24lowerrisk(RR,0.76;95CI,0.501.16)oIdevelopingtype2diabetes whencomparedwiththoseconsuming1.2servingsperday.Thisstudyhasthelargest sample size oI the available studies and used a validated FFQ with repeated measurements.AsigniIicantinverserelationbetweenintakeoIIruitandvegetablesanddiabetes riskwasobservedinwomenenrolledinNHEFSintheUSA(182).Amongthe5791 women participants, those consuming Iive or more servings oI Iruit and vegetables per day hadasigniIicantlylowerrisk(RR,0.61;95CI,0.420.88)oIdevelopingdiabetesthan thoseconsumingnone.However,associationsoIIruitandvegetableintakewithdiabetes incidence were not signiIicant among men in this study (RR, 1.14; 95 CI, 0.671.93).A singledietaryrecallwasusedasthemeasureoIdietaryassessmentinthisstudy;the limitationsoIsingle24-hdietaryrecallsarewell-knownandincludesigniIicant misclassiIicationoIusualintakes.Inaddition,totalenergyintakewasnotincludedinthe adjustment scheme and is likely to have aIIected results. TheresultsIromtheseprospectiveinvestigationsregardingIruitandvegetable intake and risk oI diabetes are not entirely consistent.For instance, evidence Irom the Iowa Women`sHealthStudydidnotshowanassociationbetweenIruitandvegetable consumptionandtheincidenceoIdiabetesoversixyearsoIIollow-up(50).However,in thisstudy,onlyasingledietaryassessmentwasobtained.Questionnairesanddeath certiIicates were used to identiIy end-points rather than oral glucose tolerance tests or blood glucoseconcentrationsusedinotherstudies.Inaddition,BMIandwaisthipratiowere bothincludedintheabovemodelswhichmayleadtoover-adjustmentIorobesity.Ina randomizedtrialoIthreestrategiesIordiabetespreventioninChinainvolving577 31 participantswithimpairedglucosetolerance,thoseassignedtoadietwithemphasison higher intake oI Iruit and vegetables experienced a 24 lower incidence oI type 2 diabetes than the control group during six years oI study Iollow-up (8). In summary, results oI the available studies support a role Ior Iruit and vegetables in the prevention oI type 2 diabetes independently oI other dietary and liIestyle Iactors. Large randomized controlled trials which speciIically evaluate the eIIicacy oI Iruit and vegetables independentoIotherIactorsinthepreventionoItype2diabetesmaynotbeIeasibleat present. ThereIore, additional larger and high-quality prospective cohort studies are needed to evaluate the eIIectiveness oI intake oI general and speciIic types oI Iruit and vegetables in the prevention oI type 2 diabetes. 7.6onc|us|ons 7.1 8ummary of ev|dence Since the reviews by Ness and Powles (155, 156) which identiIied Iive prospective studies inwhichintakewasmeasuredintermsoIwholeIruitandvegetables,nineprospective cohortstudiesrelatingintaketoischaemicheartdiseaseandeightprospectivecohort studiesevaluatingintakeandriskoIstrokehavebeenconducted.Fiveprospectivecohort studiesoItherelationshipbetweenIruitandvegetableintakeandthedevelopmentoI diabetestype2wereidentiIied.ThesestudiesareonthewholestronglysuggestiveoIa causal role Ior Iruit and vegetable intake in the primary prevention oI CVDs and diabetes. Random-eIIectmodelswereusedtocombinemeasuresoIassociationIrom14 prospectivestudiesproducingasummaryRRoI0.85Iorischaemicheartdisease,witha 95 CI oI 0.800.90, (p 0.001) Ior persons in the highest quantile oI Iruit and vegetable intake compared with those in the lowest.For stroke, data Irom 11 studies demonstrated a summaryRRoI0.80,and95CIoI0.670.94,(p0.005)Iorpersonsinthehighest quantile oI Iruit and vegetable intake compared with those in the lowest.FewprospectivedatawereavailablerelatingIruitandvegetableintaketoriskoI diabetesmellitus.Onthewhole,studieswerediIIiculttocompareduetotheir methodologicaldiIIerencesandtheabovesummaryRRmeasuresshouldbeinterpreted 32 withcaution.DuetotheseimportantdiIIerences,NessandPowlesdeclinedtocreatea summarymeasureintheirreview.Theissuesinvolvedinpreparingsuchasummary measureIorIruitandvegetableintakehavealsobeenreviewedbyNess,Eggers,and Powles (183). 7.2 Rev|ew of causa||ty Nutritional recommendations are oIten made in the absence oI randomized controlled trials, becauselittlesuchevidenceexists.Thegeneralcriteriausedtosupportcausalityinclude consistency, strength oI association, dose response, biological plausibility, and temporality (184). The inverse relationship between the consumption oI Iruit and vegetables and CVDs (ischaemicheartdiseaseandstroke)issupportedbyevidenceIromecologic,cross-sectional,casecontrol,andprospectivestudies(155).Theinverserelationshipbetween Iruitandvegetableintakeanddiabetesissupportedbycross-sectional,casecontrol,and prospectivestudies.Todate,themajorityoIthesestudiesalsoreportedsigniIicantdoseresponse relationships between intake oI Iruit and vegetables and risk oI both diabetes and CVDs. OItenbiologicalplausibilitycannotbedemandedoIahypothesisbecausethe current state oI knowledge is inadequate to explain observations.However in terms oI the Iindingspresentedhere,experimentalandphysiologicalevidencesupportstherolesoI nutrients abundant in Iruit and vegetables such as Iibre, potassium, Ilavonoids, carotenoids, Iolicacidandvegetableproteins,andtheirlowglycaemicindex,inreducingriskoI ischaemic heart disease, stroke and diabetes.Since dietary data were collected at baseline andpersonswithCVDordiabetesatbaselinewereexcludedinalloIthecohortstudies reportedIortheseoutcomes,respectively,exposureprecededtheclinicaloutcomeoI interest and the criterion oI a temporal relationship is IulIilled.Taken together, the totality oI the evidencestronglysupports the notion that Iruit and vegetable intake reduces risk oI ischaemic heart disease, stroke and diabetes, independently oI other health habits. 7.3 8tud|es |n deve|op|ng countr|es 33 EcologicstudiesoIIruitandvegetableintakeandCVDshavebeenconductedacross countriesincludingthosethataredevelopingandinepidemiologictransition(155).However,individualleveldietarydataandoutcomemeasuresareneededtoexamine prospectivelytheassociationsbetweenIruitandvegetableintakeandCVDs.BecauseoI thediIIicultiesinherentinaccuratelymeasuringdietaryintake,andthelargesamplesizes andlongIollow-upoItenneededtoprovideadequatepowerinstudiesoInutritional exposuresandchronicdisease,thecostoIconductingcohortstudiestoexamineIruitand vegetable intake in relation to diabetes and CVD is high.The study populations included in thereviewoIprospectiveevidenceregardingIruitandvegetableintakewereinEurope (Denmark, Finland, Netherlands, United Kingdom), Japan, and USA. The literature search described above did not identiIy prospective studies oI Iruit and vegetable intake and CVD ordiabetesincidenceIromdevelopingcountries.AsaIirststep,evidenceIromIood balancesheetsmaybehelpIultoestimatetheimpactoIinadequateIruitandvegetable intake on health in developing countries. 7.4 Future research needs CVD takes a long time to develop. This Iact together with the diIIiculty oI managing long-term dietary interventions or controlled Ieeding trials, and the large sample size required to obtainan appropriate level oI statistical power,means thatrandomized controlled trials oI Iruitandvegetable-enricheddietstopreventCVDsarenotIeasibleatthistime.Itis thereIoreparticularlyimportantthatadditionallargerandhigh-qualityprospectivecohort studies are conducted to evaluate the eIIectiveness oI intake oI general and speciIic types oI IruitandvegetablesIorthepreventionoICVDsanddiabetes.Lowpowerduetosmall eventratescansigniIicantlyaIIectstudiesoIIruitandvegetableintakeandCVDbecause the inherent diIIiculty in measuring diet. EIIect sizes in nutritional epidemiologyare oIten smallbutimportant.Largestudiesthatarewell-conductedandhavehighpowertodetect such associations are needed.StudiestoevaluatewhichparticularIruitandvegetablesaremosteIIectiveinthe prevention oI diabetes and CVDs would be helpIul. For example, diIIerences in the nutrient contentoIdiIIerentgroupsoIIruitsandvegetables(e.g.cruciIerousversusleaIy 34 vegetables)mayhaveanimpactontheirprotectiveeIIects.TheassociationsoIglycaemic index and glycaemic load should be investigated in relation to ischaemic heart disease and stroke,particularlyregardingtherolesoIstarchyvegetablessuchaspotatoandyam.The physiological aspects oI Ioods change with heat and pressure, such that their preparation is particularly important in relation to their eIIects in the body.Hence regional diIIerences in IoodpreparationcanhaveimportantramiIicationsontheriskIorCVDsanddiabetesand deserve evaluation. Moreover, types oI Iruit and vegetables diIIer in diIIerent regions oI the world. Thus studies in developing countries may help to evaluate the importance oI speciIic Iruits and vegetables which are not yet widely consumed. $ 1.The World Health Report. Shaping the Future. Geneva, World Health Organization, 2003. 2.YusuISetal.GlobalburdenoIcardiovasculardiseases:partI:general considerations,theepidemiologictransition,riskIactors,andimpactoI urbanization. Circulation, 2001, 104:27462753. 3.Mathers CD et al. Global Burden of Disease 2000. Jersion 2. methods and results. Geneva, World Health Organization, 2002. 4.TheWorldHealthReport2002.ReducingRisksandPromotingHealthvLife. Geneva, World Health Organization, 2002. 5.InternationalDiabetesFederationTaskForceonDiabetesHealthEconomic. Diabetesheatheconomics.facts,figures,andforecasts.Brussels,International Diabetes Federation, 1997. 6.KingH,AubertRE,HermanWH.GlobalburdenoIdiabetes,19952025: prevalence, numerical estimates, and projections. Diabetes Care, 1998, 21(9):141431. 7.Global Burden oI Disease, DiabetesMellitus. Geneva,World Health Organization, 2003. 35 8.PanXRetal.EIIectsoIdietandexerciseinpreventingNIDDMinpeoplewith impairedglucosetolerance.TheDaQingIGTandDiabetesStudy.DiabetesCare, 1997, 20(4):53744. 9.TuomilehtoJetal.PreventionoItype2diabetesmellitusbychangesinliIestyle among subjects with impaired glucose tolerance. New England Journal of Medicine, 2001, 344(18):134350. 10.ErikssonKF,LindgardeF.PreventionoItype2(non-insulin-dependent)diabetes mellitusbydietandphysicalexercise.The6-yearMalmoIeasibilitystudy. Diabetologia, 1991, 34(12):8918. 11.SouthgateDA.Dietaryadvice:Ioodsornutrients.ProcNutrSoc,1992.51(1):4753. 12.NelsonM,BinghamSA.AssessmentoIIoodconsumptionandnutrientintake.In: MargettsBMandNelsonM,eds.DesignConceptsinNutritionalEpidemiologv. New York, NY, OxIord University Press, 1997. 13.WillettWC. Nutritionalepidemiology.In:RothmanKJ, GreenlandS, eds. Modern Epidemiologv. Philadephia, Lippincott-Raven, 1998. 14.LiuSetal.DietaryglycaemicloadassessedbyIoodIrequencyquestionnairein relationtoplasmahigh-densitylipoproteincholesterolandIastingtriglycerides amongpostmenopausalwomen.AmericanJournalofClinicalNutrition,2001. 73:56066. 15.Krebs-SmithSMetal.UsingIoodIrequencyquestionnairestoestimateIruitand vegetableintake:associationbetweenthenumberoIquestionsandtotalintakes.J Nutr Educ, 1995, 27:8085. 16.CassidyCM.Walkamileinmyshoes:culturallysensitiveIood-habitresearch. American Journal of Clinical Nutrition, 1994, 59(1 Suppl):190S197S. 17.SargeantLAetal.Fruitandvegetableintakeandpopulationglycosylated haemoglobinlevels:theEPIC-NorIolkStudy.EuropeanJournalofClinical Nutrition, 2001, 55(5):3428. 18.SteIIen LM et al. Associations oI whole-grain, reIined-grain, and Iruit and vegetable consumptionwithrisksoIall-causemortalityandincidentcoronaryarterydisease 36 andischaemicstroke:theAtherosclerosisRiskinCommunities(ARIC)Study. American Journal of Clinical Nutrition, 2003, 78(3):38390. 19.GillmanMWetal.ProtectiveeIIectoIIruitsandvegetablesondevelopmentoI strokeinmen.JournaloftheAmericanMedicalAssociation,1995,273:11131117. 20.Kris-EthertonPM et al.Bioactive compoundsinIoods: their role in the prevention oIcardiovasculardiseaseandcancer.AmericanJournalofMedicine,2002,113 Suppl 9B:71S88S. 21.AviramMetal.PomegranatejuiceIlavonoidsinhibitlow-densitylipoprotein oxidationandcardiovasculardiseases:studiesinatheroscleroticmiceandin humans. Drugs Exp Clin Res, 2002, 28(2-3):4962. 22.Vinson JA et al. Polyphenol antioxidants in citrus juices: in vitro and in vivo studies relevant to heart disease. Adv Exp Med Biol, 2002, 505:11322. 23.Plotnick GD et al. EIIect oI supplemental phytonutrients on impairment oI the Ilow-mediatedbrachialarteryvasoactivityaIterasinglehigh-Iatmeal.JAmColl Cardiol, 2003, 41(10):17449. 24.LiuKetal.StatisticalmethodstoassessandminimizetheroleoIintra-individual variabilityinobscuringtherelationshipbetweendietarylipidsandserum cholesterol. J Chronic Dis, 1978, 31(67):399418. 25.Sempos CT et al. EIIects oI intraindividual and interindividual variation in repeated dietary records. American Journal ofEpidemiologv, 1985, 121(1):12030. 26.PotischmanN,WeedDL.Causalcriteriainnutritionalepidemiology.American Journal ofClinicalNutrition, 1999. 69(6):1309S1314S. 27.SerdulaMKetal.TheassociationbetweenIruitandvegetableintakeandchronic disease risk Iactors. Epidemiologv, 1996, 7(2):1615. 28.GregoryJetal.ThedietarvandnutritionalsurvevofBritishadults.London,Her Majesty's Stationery OIIice,1990. 29.MargettsBM,NelsonM,OverviewoItheprinciplesoInutritionalepidemiology. In:MargettsBM,NelsonM,eds.DesignConceptsinNutritionalEpidemiologv. New York, NY, OxIord University Press, 1997. 37 30.Willett WC, Buzzard IM. Nature oI variation in diet. In: Willett WC, ed. Nutritional Epidemiologv, New York, NY, OxIord University Press, 1998. 31.Hu FB et al. Dietary Iat and coronary heart disease: a comparison oI approaches Ior adjustingIortotalenergyintakeandmodelingrepeateddietarymeasurements. American Journal of Epidemiologv, 1999, 149(6):53140. 32.Mertz W. Foods and nutrients. J Am Diet Assoc, 1984, 84(7):76970. 33.MayneSTetal.DietarybetacaroteneandlungcancerriskinU.S.nonsmokers.J Natl Cancer Inst, 1994, 86(1):338. 34.Mettlin C, Graham S, Swanson M. Vitamin A and lung cancer. J Natl Cancer Inst, 1979, 62(6):14358. 35.ZieglerRGetal.ImportanceoIalpha-carotene,beta-carotene,andother phytochemicals in the etiology oI lung cancer. J Natl Cancer Inst, 1996, 88(9):612615. 36.ZieglerRGetal.DietarycaroteneandvitaminAandriskoIlungcanceramong white men in New Jersey. J Natl Cancer Inst, 1984, 73(6):142935. 37.KvaleG,BjelkeE,GartJJ.Dietaryhabitsandlungcancerrisk.International Journal of Cancer, 1983, 31(4):397405. 38.TheAlpha-Tocopherol,BetaCaroteneCancerPreventionStudyGroup.TheeIIect oI vitamin E and beta carotene on the incidence oI lung cancer and other cancers in male smokers. New England Journal of Medicine, 1994, 330(15):102935. 39.OmennGSetal.EIIectsoIacombinationoIbetacaroteneandvitaminAonlung cancerandcardiovasculardisease.NewEnglandJournalofMedicine,1996, 334(18):11501155. 40.HennekensCHetal.LackoIeIIectoIlong-termsupplementationwithbeta carotene on theincidenceoI malignant neoplasms and cardiovascular disease. New England Journal of Medicine, 1996, 334(18):11459. 41.CommitteeonDiet,Nutrition,andCancer,AssemblyoILiIeSciences,National ResearchCouncil.Diet,Nutrition,andCancer.Washington,DC,National Academy Press, 1982. 42.LynchSRetal.IronabsorptionIromlegumesinhumans.AmericanJournalof Clinical Nutrition, 1984, 40(1):427. 38 43.Preparation and use of food-based dietarv guidelines. Report oI a joint FAO/WHO consultation. Nicosia, Cyprus, World Health Organization and Food and Agriculture Organization oI the United Nations, 1996. 44.AndersonJWetal.Postprandialserumglucose,insulin,andlipoproteinresponses to high- and low-Iiber diets. Metabolism, 1995, 44(7):84854. 45.Ludwig DS et al. Dietary Iiber, weight gain, and cardiovascular disease risk Iactors in young adults. Journal of the American Medical Association, 1999, 282(16):153946. 46.SalmeronJetal.DietaryIiber,glycaemicload,andriskoINIDDMinmen. Diabetes Care, 1997, 20(4):54550. 47.SalmeronJetal.DietaryIiber,glycaemicload,andriskoInon-insulin-dependent diabetesmellitusinwomen.JournaloftheAmericanMedicalAssociation,1997, 277(6):4727. 48.MarshallJA,HammanRF.HighsaturatedIatandlowstarchandIibreare associatedwithhyperinsulinaemiainanon-diabeticpopulation:TheSanLuis Valley Diabetes Study. Diabetologia, 1997, 40:430438. 49.FeskensEJ,KromhoutD.DietandphysicalactivityasdeterminantsoI hyperinsulinemia:theZutphenElderlyStudy.AmericanJournalofEpidemiologv, 1994, 140:350360. 50.MeyerKAet al. Carbohydrates, dietary Iiber, and incident type 2 diabetes in older women. American Journal of Clinical Nutrition, 2000, 71(4):92130. 51.Stevens J et al. Dietary Iiber intake andglycaemic index and incidence oIdiabetes inAIrican-Americanandwhiteadults:theARICstudy.DiabetesCare,2002, 25(10):171521. 52.Montonen J et al. Whole-grain and Iiber intake and the incidence oI type 2 diabetes. American Journal of Clinical Nutrition, 2003, 77(3):622629. 53.Burton-Freeman B. Dietary Iiber and energy regulation. Journal of Nutrition, 2000, 130(2S Suppl):272S275S. 54.Bazzano LA et al. Dietary Iiber intake and reduced risk oI coronary heart disease in USmenandwomen:theNationalHealthandNutritionExaminationSurveyI 39 EpidemiologicFollow-upStudy.ArchivesofInternalMedicine,2003, 163(16):1897904. 55.LiuSetal.AprospectivestudyoIdietaryIiberintakeandriskoIcardiovascular disease among women. J Am Coll Card, 2002, 39:4956. 56.MozaIIarianDetal.Cereal,Iruit,andvegetableIiberintakeandtheriskoI cardiovasculardiseaseinelderlyindividuals.JournaloftheAmericanMedical Association, 2003, 289(13):165966. 57.Pietinen P et al. Intake oI Dietary Iiber and risk oI coronary heart disease in a cohort oIFinnishmen:TheAlpha-tocopherol,Beta-caroteneCancerPreventionStudy. Circulation, 1996, 94:27202727. 58.Pereira MA et al. Dietary Iiber and risk oI coronary heart disease: a pooled analysis oI cohort studies. Archives of Internal Medicine, 2004, 164(4):3706. 59.RimmEBetal.Vegetable,Iruit,andcerealIiberintakeandriskoIcoronaryheart disease among men. Journal of the American Medical Association, 1996, 275:447451. 60.ReavenGM.PathophysiologyoIinsulinresistanceinhumandisease.PhvsiolRev, 1995, 75(3):47386. 61.RipsinCMetal.Oatproductsandlipidlowering.Ameta-analysis.Journalofthe American Medical Association, 1992, 267(24):331725. 62.HeJ,WheltonPK.EIIectoIdietaryIiberandproteinintakeonbloodpressure:a review oI epidemiologic evidence. Clin Exp Hvpertens, 1999, 21(5-6):78596. 63.HeJetal.EIIectoIdietaryIiberintakeonbloodpressure:arandomized,double-blind, placebo-controlled trial. J Hvpertens, 2004, 22(1):7380. 64.LiuS,MansonJ.Dietarycarbohydrates,physicalinactivity,obesity,andthe 'metabolicsyndrome'aspredictorsoIcoronaryheartdisease.CurrentOpinionin Lipidologv, 2001, 12:395404. 65.Liu S et al. A prospective study oI dietary glycaemic load, carbohydrate intake, and riskoIcoronaryheartdiseaseinUSwomen.AmericanJournalofClinical Nutrition, 2000, 71(6):145561. 66.JenkinsDJetal.GlycaemicindexoIIoods:aphysiologicbasisIorcarbohydrate exchange. American Journal of Clinical Nutrition, 1981, 34:362366. 40 67.WillettW,MansonJ,LiuS.Glycaemicindex,glycaemicload,andriskoItype2 diabetes. American Journal of Clinical Nutrition, 2002. 76(1):274S80S. 68.LudwigDS.Dietaryglycaemicindexandobesity.JournalofNutrition,2000, 130(2S Suppl):280S283S. 69.BallSDetal.ProlongationoIsatietyaIterlowversusmoderatelyhighglycaemic index meals in obese adolescents. Pediatrics, 2003, 111(3):48894. 70.FeskensEJetal.CardiovascularriskIactorsandthe25-yearincidenceoIdiabetes mellitusinmiddle-agedmen.TheZutphenStudy.AmericanJournalof Epidemiologv, 1989, 130:11011108. 71.Colditz GA et al. Diet and risk oI clinical diabetes in women. American Journal of Clinical Nutrition, 1992, 55(5):101823. 72.FeskensEJ,KromhoutD.Carbohydrateintakeandbodymassindexinrelationto theriskoIglucoseintoleranceinanelderlypopulation.AmericanJournalof Clinical Nutrition, 1991, 54:136140. 73.JanketSJetal.AprospectivestudyoIsugarintakeandriskoItype2diabetesin women. Diabetes Care, 2003, 26(4):100815. 74.HuFBetal.Diet,LiIestyle,andtheRiskoIType2DiabetesMellitusinWomen. New England Journal of Medicine, 2001, 345(11):790797. 75.ParkYK,YetleyEA.IntakesandIoodsourcesoIIructoseintheUnitedStates. American Journal of Clinical Nutrition, 1993. 58(5 Suppl):737S747S. 76.MayesPA.IntermediarymetabolismoIIructose.AmericanJournalofClinical Nutrition, 1993, 58(5 Suppl):754S765S. 77.ElliottSSetal.Fructose,weightgain,andtheinsulinresistancesyndrome. American Journal of Clinical Nutrition, 2002, 76(5):91122. 78.HollenbeckCB.DietaryIructoseeIIectsonlipoproteinmetabolismandriskIor coronaryarterydisease.AmericanJournalofClinicalNutrition,1993,58(5 Suppl):800S809S. 79.JeppesenJetal.PostprandialtriglycerideandretinylesterresponsestooralIat: eIIects oI Iructose. American Journal of Clinical Nutrition, 1995, 61(4):78791. 80.MalerbiDAetal.MetaboliceIIectsoIdietarysucroseandIructoseintypeII diabetic subjects. Diabetes Care, 1996, 19(11):124956. 41 81.SelhubJetal.VitaminstatusandintakeasprimarydeterminantsoI homocysteinemiainanelderlypopulation.JournaloftheAmericanMedical Association, 1993, 270(22):26938. 82.StampIerMJetal.AprospectivestudyoIplasmahomocyst(e)ineandriskoI myocardialinIarctioninUSphysicians.JournaloftheAmericanMedcial Association, 1992, 268:877881. 83.SelhubJetal.Associationbetweenplasmahomocysteineconcentrationsand extracranialcarotid-arterystenosis.NewEnglandJournalofMedicine,1995, 332(5):28691. 84.Wilmink HWet al. InIluence oI Iolic acid on postprandial endothelial dysIunction. Arterioscler Thromb Jasc Biol, 2000, 20(1):1858. 85.Vermeulen EG et al. EIIect oI homocysteine-lowering treatment with Iolic acid plus vitaminB6onprogressionoIsubclinicalatherosclerosis:arandomised,placebo-controlled trial. Lancet, 2000, 355:51722. 86.GilesWHetal.SerumIolateandriskIorcoronaryheartdisease:resultsIroma cohort oI US adults. Annals of Epidemiologv, 1998, 8(8):4906. 87.Boushey CJ et al. A quantitative assessment oI plasma homocysteine as a risk Iactor Iorvasculardisease.ProbablebeneIitsoIincreasingIolicacidintakes.Journalof the American Medical Association, 1995, 274(13):104957. 88.Morrison HI et al.Serum Iolate and risk oI Iatal coronary heart disease. Journal of the American Medical Association, 1996, 275:18931896. 89.Rimm EB et al. Folate and vitamin B6 Irom diet and supplements in relation to risk oIcoronaryheartdiseaseamongwomen.JournaloftheAmericanMedical Association, 1998, 279(5):35964. 90.Bazzano LA et al. Dietary intake oI Iolate and risk oI stroke in US men and women: NHANESIEpidemiologicFollow-upStudy.NationalHealthandNutrition Examination Survey. Stroke, 2002, 33(5):11838. 91.BloomOJ,McDiarmidT,ScovilleC.Doantioxidants(vitaminsC,E)improve outcomes in patients with coronary artery disease? J Fam Pract, 2002, 51(11):978. 92.AgarwalS,RaoAV.Tomatolycopeneanditsroleinhumanhealthandchronic diseases. Canadian Medical Association Journal, 2000, 163(6):73944. 42 93.YochumLetal.DietaryIlavonoidintakeandriskoIcardiovasculardiseasein postmenopausal women. American Journal of Epidemiologv, 1999, 149(10):9439. 94.SessoHDetal.Dietarylycopene,tomato-basedIoodproductsandcardiovascular disease in women. Journal of Nutrition, 2003, 133(7):233641. 95.Paolisso G et al. Evidence Ior a relationship between Iree radicals and insulin action in the elderly. Metabolism, 1993, 42(5):65963. 96.PaolissoGetal.PharmacologicdosesoIvitaminEimproveinsulinactionin healthysubjectsandnon-insulin-dependentdiabeticpatients.AmericanJournalof Clinical Nutrition, 1993, 57(5):6506. 97.Oberley LW. Free radicals and diabetes. Free Radic Biol Med, 1988, 5(2):11324. 98.WolIISP.DiabetesmellitusandIreeradicals.Freeradicals,transitionmetalsand oxidativestressintheaetiologyoIdiabetesmellitusandcomplications.British Medical Bulletin, 1993, 49(3):64252. 99.FordESetal.Diabetesmellitusandserumcarotenoids:IindingsIromtheThird NationalHealthandNutritionExaminationSurvey.AmericanJournalof Epidemiologv, 1999. 149(2):16876. 100.FeskensEJetal.DietaryIactorsdeterminingdiabetesandimpairedglucose tolerance.A20-yearIollow-upoItheFinnishandDutchcohortsoItheSeven Countries Study. Diabetes Care, 1995, 18(8):110412. 101.SalonenJTetal.IncreasedriskoInon-insulindependentdiabetesmellitusatlow plasmavitaminEconcentrations:aIouryearIollowupstudyinmen.British Medical Journal, 1995, 311(7013):11247. 102.ReunanenAetal.SerumantioxidantsandriskoInon-insulindependentdiabetes mellitus. European Journal of Clinical Nutrition, 1998, 52(2):8993. 103.HeJ,WheltonPK.Potassium,bloodpressure,andcardiovasculardisease:an epidemiologic perspective. Cardiologv in Review, 1997, 5:255260. 104.WheltonPKetal.EIIectsoIoralpotassiumonbloodpressure.Meta-analysisoI randomized controlled clinical trials. Journal of the American Medical Association, 1997, 277(20):162432. 43 105.KrishnaGG,MillerE,KapoorS.Increasedbloodpressureduringpotassium depletioninnormotensivemen.NewEnglandJournalofMedicine,1989, 320(18):117782. 106.KrishnaGG,KapoorSC.Potassiumdepletionexacerbatesessentialhypertension. Annals of Internal Medicine, 1991, 115(2):7783. 107.XieJXetal.TherelationshipbetweenurinarycationsobtainedIromthe INTERSALTstudyandcerebrovascularmortality.JHumHvpertens,1992,6:1721. 108.KhawKT, Barrett-Connor E.Dietary potassium and stroke-associatedmortality. A 12-yearprospectivepopulationstudy.NewEnglandJournalofMedicine,1987, 316:235240. 109.AscherioAetal.IntakeoIpotassium,magnesium,calcium,andIiberandriskoI stroke among US men. Circulation, 1998, 98(12):1198204. 110.BazzanoLAetal.DietarypotassiumintakeandriskoIstrokeinUSmenand women: National Health and Nutrition Examination Survey I epidemiologic Iollow-up study. Stroke, 2001, 32(7):147380. 111.PaolissoGetal.Magnesiumandglucosehomeostasis.Diabetologia,1990, 33(9):5114. 112.SheehanJP.MagnesiumdeIiciencyanddiabetesmellitus.MagnesTraceElem, 1991, 10(2-4):2159. 113.MaJetal.AssociationsoIserumanddietarymagnesiumwithcardiovascular disease,hypertension,diabetes,insulin,andcarotidarterialwallthickness:the ARICstudy.AtherosclerosisRiskinCommunitiesStudy.JournalofClinical Epidemiologv, 1995, 48(7):92740. 114.Manolio TA et al. Correlates oI Iasting insulin levels in young adults: the CARDIA study. Journal of Clinical Epidemiologv, 1991, 44(6):5718. 115.World Health Organization Global Strategy on Diet, Physical Activity, and Health: Fact Sheet Obesitv and Overweight. Geneva, World Health Organization, 2003. 116.WolIAM,ColditzGA.CurrentestimatesoItheeconomiccostoIobesityinthe United States. Obesitv Research, 1998. 6(2):97106. 44 117.Colditz GA et al.Weight as a risk Iactor Iorclinical diabetesinwomen. American Journal of Epidemiologv, 1990, 132(3):50113. 118.ColditzGAetal.WeightgainasariskIactorIorclinicaldiabetesmellitusin women. Annals of Internal Medicine, 1995, 122(7):4816. 119.SjostromCDetal.ReductioninincidenceoIdiabetes,hypertensionandlipid disturbancesaIterintentionalweightlossinducedbybariatricsurgery:theSOS Intervention Study. Obesitv Research, 1999, 7(5):47784. 120.PoriesWJetal.SurgicaltreatmentoIobesityanditseIIectondiabetes:10-y Iollow-up. American Journal of Clinical Nutrition, 1992, 55(2 Suppl):582S585S. 121.AndersonJW,KendallCWC,JenkinsDJA.ImportanceoIWeightManagementin Type2Diabetes:ReviewwithMeta-analysisoIClinicalStudies.JAmCollNutr, 2003, 22(5):331339. 122.Henry RR Gumbiner B. BeneIits and limitations oI very-low-calorie diet therapy in obese NIDDM. Diabetes Care, 1991, 14(9):80223. 123.Wing RRet al. Caloricrestriction per se isa signiIicant Iactor in improvements in glycaemiccontrolandinsulinsensitivityduringweightlossinobeseNIDDM patients. Diabetes Care, 1994, 17(1):306. 124.ResnickHEetal.RelationoIweightgainandweightlossonsubsequentdiabetes risk in overweight adults. J Epidemiol Communitv Health, 2000, 54(8):596602. 125.Moore LL et al. Can sustained weight loss in overweight individuals reduce the risk oI diabetes mellitus? Epidemiologv, 2000, 11(3):26973. 126.ObarzanekEetal.EIIectsonbloodlipidsoIabloodpressure-loweringdiet:the DietaryApproachestoStopHypertension(DASH)Trial.AmericanJournalof Clinical Nutrition, 2001, 74(1):809. 127.SinghRBetal.EIIectoIIat-modiIiedandIruit-andvegetable-enricheddietson blood lipids in the Indian Diet Heart Study. American Journal of Cardiologv, 1992, 70(9):86974. 128.SinghRB,GhoshS,SinghR.EIIectsonserumlipidsoIaddingIruitsand vegetablestoprudentdietintheIndianExperimentoIInIarctSurvival(IEIS). Cardiologv, 1992, 80(3-4):28393. 45 129.Djousse L et al. Fruit and vegetable consumption and LDL cholesterol: the National Heart, Lung, and Blood Institute Family Heart Study. American Journal of Clinical Nutrition, 2004, 79(2):2137. 130.Anderson JW, Johnstone BM, Cook-Newell ME. Meta-analysis oI the eIIects oI soy proteinintakeonserumlipids.NewEnglandJournalofMedicine,1995, 333(5):27682. 131.AndersonJW,SmithBM,WashnockCS.CardiovascularandrenalbeneIitsoIdry beanandsoybeanintake.AmericanJournalofClinicalNutrition,1999,70(3 Suppl):464S474S. 132.JenkinsDJetal.LeguminousseedsinthedietarymanagementoIhyperlipidemia. American Journal of Clinical Nutrition, 1983, 38(4):56773. 133.Lin BW et al. EIIects oI bean meal on serum cholesterol and triglycerides. Chinese Medical Journal (Engl), 1981, 94(7):4558. 134.Anderson JW, GustaIson NJ. Hypocholesterolemic eIIects oI oat and bean products. American Journal of Clinical Nutrition, 1988, 48(3 Suppl):74953. 135.AndersonJWetal.HypocholesterolemiceIIectsoIoat-branorbeanintakeIor hypercholesterolemicmen.AmericanJournalofClinicalNutrition,1984, 40(6):114655. 136.Mathur KS, Khan MA, Sharma RD. Hypocholesterolaemic eIIect oI Bengal gram: a long-term study in man. British Medical Journal, 1968, 1(583):3031. 137.AndersonJW,MajorAW.Pulsesandlipaemia,short-andlong-termeIIect: potentialinthepreventionoIcardiovasculardisease.BritishJournalofNutrition, 2002, 88 Suppl 3:S26371. 138.VanHornL.Fiber,lipids,andcoronaryheartdisease.AstatementIorhealthcare proIessionalsIromtheNutritionCommittee,AmericanHeartAssociation. Circulation, 1997, 95(12):27014. 139.RouseIL etal. Blood-pressure-lowering eIIectoI a vegetarian diet: controlled trial in normotensive subjects. Lancet, 1983, 1(8314-5):510. 140.AppelLJetal.AclinicaltrialoItheeIIectsoIdietarypatternsonbloodpressure. DASHCollaborativeResearchGroup.NewEnglandJournalofMedicine,1997, 336(16):111724. 46 141.MargettsBMetal.Vegetariandietinmildhypertension:arandomisedcontrolled trial.BritishMedicalJournal(ClinicalResearchEdition),1986,293(6560):146871. 142.Sacks FM, Rosner B, Kass EH. Blood pressure in vegetarians. American Journal of Epidemiologv, 1974, 100(5):3908. 143.Miura K et al. Relation oI vegetable, Iruit, and meat intake to 7-year blood pressure change in middle-aged men: the Chicago Western Electric Study. American Journal of Epidemiologv, 2004, 159(6):57280. 144.Singh RBet al. Can guava Iruitintake decreaseblood pressureand blood lipids? J Hum Hvpertens, 1993, 7(1):338. 145.MillerER3rdetal.ResultsoItheDiet,Exercise,andWeightLossIntervention Trial (DEW-IT). Hvpertension, 2002, 40(5):6128. 146.ArmstrongBKetal.Commodityconsumptionandischaemicheartdisease mortality,withspecialreIerencetodietarypractices.JChronicDis,1975, 28(9):45569. 147.CriquiMH,RingelBL.DoesdietoralcoholexplaintheFrenchparadox?Lancet, 1994. 344(8939-8940):171923. 148.ByingtonR,DyerA,GarsideD.RecenttrendsoImajorcoronaryriskIactorsand CHDmortalityintheUnitedStatesandotherindustrializedcountries.In: Procedings of the Conference on the Decline of Coronarv Heart Disease Mortalitv. Washington, DC, US Dept oI Health, NIH publication No 79-1610, 1979. 149.CrombieIKet al. Geographical clustering oI riskIactors and liIestyle Iorcoronary heart disease in the Scottish Heart Health Study. British Heart Journal, 1990, 64(3): 199203. 150.BellizziMCetal.VitaminEandcoronaryheartdisease:theEuropeanparadox. European Journal of Clinical Nutrition, 1994, 48(11):82231. 151.GramenziAetal.AssociationbetweencertainIoodsandriskoIacutemyocardial inIarction in women. British Medical Journal, 1990, 300(6727):7713. 152.Knox EG. Foods and diseases. Br J Prev Soc Med, 1977, 31(2):7180. 153.SinhaDP.FoodandnutritionsurveillanceintheEnglish-speakingCaribbean. Bulletin of the Pan American Health Organi:ation, 1989, 23(4):45760. 47 154.Verlangieri AJ et al. Fruit and vegetable consumption and cardiovascular mortality. Medical Hvpotheses, 1985, 16(1):715. 155.NessAR,PowlesJW.Fruitandvegetables,andcardiovasculardisease:areview. International Journal of Epidemiologv, 1997, 26(1):113. 156.Ness AR, Powles JW. The role oI diet, Iruit and vegetablesand antioxidants in t