味精安全问题课件

Umami/MSG:SafetyIssues

味精的安全问题JohnD.Fernstrom,Ph.D.Professor-UniversityofPittsburghSchoolofMedicine匹兹堡大学医学院教授ScientificAdvisor-IGTCIGTC科学顾问Outline内容纲要Briefreviewoforiginalissuesleadingtoexpressionofconcerninearly1970s

简要回顾上世纪70年代初引起关注的安全问题Briefsummaryofsafetyviewsnow

简单总结当前关于味精安全的观点Examinationoftwogeneralissues两大类问题Neurotoxicity神经毒性GeneralAdverseEffects(e.g.,MSGSymptomComplex)所有不良反应（如味精综合症）Conclusions

结论KwokRHM

Chinese-RestaurantSyndrome中国餐馆综合症

NewEnglJMed

278:796,1968(letter)

1968年新英格兰医学杂志（通讯）FirstreportofadversesymptomsinhumansassociatedwiththeingestionofChinesefoodthatsuggestedapossiblelinktoMSG(aswellasmanyotheringredients).首例报道人体摄入中国食品后出现不适症状可能与所添加的味精有关（也可能是其他添加成分）Ananecdotalcase-report.单例报告（缺乏足够科学依据）SchaumbergHHetal.

MonosodiumL-Glutamate:ItsPharmacology&RoleintheChineseRestaurantSyndrome

Science163:826-828,1969

谷氨酸单钠的药理学及其在中国餐馆并发症中的角色

《科学》163期，826-828页，1969DefinedMSG"SymptomTriad“味精“三种并发症状”表现为Burning灼烧感FacialPressure面部紧张ChestPain胸痛Skeletalstunting骨萎缩Markedobesity明显肥胖Sterility不育Hypothalamiclesions下丘脑损伤MSGINJECTED注射味精后OlneyJW.

BrainLesions,ObesityandOtherDisturbancesinMiceTreatedwithMonosodiumGlutamate.

SCIENCE164:719-721,1969.

小白鼠注射味精后出现大脑损伤，肥胖以及其他系统紊乱

1969年科学杂志ConventionalToxicologicdatabaseforreviewbyJECFAwasveryextensive,includingacute,subchronic&chronictoxicitystudiesinrats,mice&dogs,togetherwithstudiesonreproductivetoxicityandteratology供食品添加剂联合专家委员会审查的常规毒性数据资料非常完整，包括大白鼠、小白鼠和狗的急性，亚慢性，慢性毒性研究以及遗传性毒性和畸形学研究。TheSafetyEvaluationofMonosodiumGlutamateWalkerR,LupienJRJournalofNutrition130:1049S-1052S,2000.味精的安全评估2000年营养学杂志Neurotoxicity神经毒性研究DietaryMSG食用味精

Plasma(GLU)血浆（谷氨酸）上升

Brain(GLU)大脑（谷氨酸）上升

Neuronalexcitation&death神经兴奋和死亡BarrierstoNeurotoxicity

GastrointestinalTractefficientlyusesingestedGLU(MSG)asE-source(95+%).胃肠道能有效地吸收95%以上的谷氨酸钠作为能源GutisthusabarriertoGLUentryintoblood.肠道因此能阻止谷氨酸进入血液中Blood-BrainBarrierpreventsGLUpenetrationintobrain.血脑屏障阻止谷氨酸渗透到大脑OnlyveryhighoraldosesofMSGbygavagecanraiseplasmaGLUenoughtogetGLUintobrain只有灌喂大剂量的味精，才会致血浆中的谷氨酸含量升高，而进入到大脑MSGinfood

doesnothavethiseffect.食物中添加的味精不会有这种效果FernstromJDetal.JClinEndocrinolMetab

81:184-191,1996.1996年，临床内分泌代谢杂志Adultmales(80kg)quicklyingestedMSG,12.7g(150mg/kg)

insolution.成年男子（体重约80公斤）能很快吸收溶液中12.7g（约150毫克每公斤）的味精TsaiP-J,HuangP-CMetabolism48:1455-1460,1999.Arrows=mealorsnack箭头代表摄取的食物或点心Meals:0745,1215,1800h饮食时间：0745，1215，1800DailyMSGdose=100mg/kg:每日摄入味精量：100mg/kgBreakfast:15mg/kg早餐：15mg/kgLunch:40mg/kg午餐:40mg/kgDinner45mg/kg晚餐：45mg/kgDataaremeans±sem(n=10)数据：均值±标准差Blackcircle:noMSG黑圈表示不含味精Whitecircle:MSG.白圈表示含有味精

GLUinjectionipstimulatesPRLsecretioninratsDoesGLU(MSG)ingestionstimulatePRLsecretioninhumans?腹腔注射谷氨酸钠会刺激小白鼠催乳素的分泌，它会对人体产生同样的作用吗？12.7goralloadofMSGinmalesubjects雄性研究对象12.7克口服PlasmaPRLinratsinjectedwithMSG(1000mg/kgip).From:TerryLCetal.BrainResearch217:129-142,1981.RatsHumansPlacentalBarriertoMaternalGlutamate胎盘屏障母体中的谷氨酸钠SteginkLDetalAmJObstetGynecol122:70-78(1975)Monkeystudy.猴子实验Highestdose(400mg/kgiv,opencircles)producedplasmaGLU70-timesnormal.BattagliaFC.JNutrition

130:974S-977S(2000)EffectoforalMSGloadingonbreastmilkfreeGLUconcentrationsinlactatingwomen哺乳妇女食用味精后母乳不会有谷氨酸钠Lactatingwomeningested100mg/kgMSGincapsuleswithwater,andmilksamplesweretakenattheindicatedtimesthereafter.ThisdoseraisedplasmaGLUfrom45nmol/mltopeakvaluesofabout300nmol/mlin30-45min.From:BakerGLetal.,Factorsinfluencingdicarboxylicaminoacidcontentofhumanmilk.In:GlutamicAcid:AdvancesinBiochemistry&Physiology,FilerLJetal.,ed.NewYork,RavenPress,1979,pp.111-123.哺乳期女性加水摄入100mg/kg的胶囊，对其后特定时间的母乳样品进行检验表明：这一剂量使得血液谷氨酸浓度在30-45分钟内从45nmol/ml提高到峰值约300nmol/ml。From:BakerGLetal.,Factorsinfluencingdicarboxylicaminoacidcontentofhumanmilk.In:GlutamicAcid:AdvancesinBiochemistry&Physiology,FilerLJetal.,ed.NewYork,RavenPress,1979,pp.111-123.影响人体母乳二氨基酸浓度的因素谷氨酸：生物化学和生理学进展BrainIssues大脑问题

RelevancetohumanMSGingestion:有关人体摄入味精TheplacentablocksGLUtransferfrommaternalintofetalblood:FETALbrainissafe.胎盘会阻止谷氨酸从母体传递给胎儿：胎儿大脑不会受到影响Breastmilk(GLU)doesnotrisewhenmotheringestshigh-doseMSG:NEWBORN/INFANTbrainissafe.当母体摄入大剂量的味精母乳中的谷氨酸含量不会上升：新生儿的脑发育是安全的InfantmetabolizesGLUatsamerateasadult(Steginketal.,PediatricRes20:53-58,1986).婴幼儿具有和成年人同样的谷氨酸代谢的能力BrainIssues大脑问题

Thehumanbrainisunaffectedbytheveryhighplasma(GLU)followinghighdoseMSGintake摄入大量的味精导致的血浆中高谷氨酸含量不会对人体大脑产生影响NodoseofMSGhasyetbeengiventohumanshighenoughtoinduceCNSeffects.至今亦未发现食用味精会影响人体中枢神经系统CRS/Allergy

(MSGSymptomComplex)中国餐馆综合症/过敏症味精综合症StudyingMSGSymptomComplex

味精综合症研究Canreproduciblesymptomsbedefined?能定义这些重复性的症状么？Arereproduciblesymptomsdose-related?这些重复性症状与摄入剂量有关吗?DoMSG-sensitiveindividualsexist?对味精敏感的个体存在吗？SYMPTOMSATTRIBUTEDTOMSG:味精所致症状Burning,tightness,numbnessinupperchest,neckandface.发烧，身体发紧，胸腔上部发闷，脖子、面部发麻Dizziness,headache眩晕，头疼Chestpain,palpitation胸口痛，心悸Weakness乏力Nausea,vomiting反胃呕吐Bronchospasm(asthmatics)哮喘Hives(urticaria)麻疹MECHANISMSUNKNOWN机制未知Multicenter,double-blind,placebo-controlled,multiple-challengeevaluationofreportedreactionstomonosodiumglutamate.GehaRSetal.JAllergyClinImmunol

106:973-80,2000味精反应的多中心、双盲、安慰剂控制、多重治疗评估报告2000年过敏与临床免疫学杂志ProtocolA:

130self-styledMSG-sensitiveindividuals.Fasted, challengeblindwithplaceboorMSG(5ginliquid).实验A：130例自认为MSG过敏者，禁食，以安慰剂或MSG(5克液体)进行盲试。ProtocolB: Subjectshadpositiveresponseof≥2symptomsto

eitherorbothtreatmentsinA(i.e.,placeboresponders too).Fast,blindchallengewith0,1.25,2.5or5g MSG(inliquid).实验B:对A中，出现阳性反应的实验对象，超过2种症状（例如：对安慰剂反应也一样）。禁食，以0，1.25，2.5或5克MSG(液体)进行盲试。GehaRSetal.,JAllergyClinImmunol

106:973-80,2000ProtocolC: Subjectshadpositiveresponseof≥2symptomsto5 gMSGbutnotplaceboinAorB.Fast,placebo(suc- rose)orMSG(5g),incapsules(blind).Dotwice.实验C:对A和B中阳性反应的实验对象-对5克MSG出现超过2种症状（对安慰剂没有），禁食，以胶囊性的安慰剂（蔗糖）或MSG(5克)，进行盲试。重复实验。ProtocolD: SubjectshadpositiveresponsetobothMSGchal- lengesinC.Fast,breakfast&placebo(sucrose) orMSG(5g),incapsules(blind).Dothreetimes.实验D:对C中MSG治疗出现阳性反应的实验对象，禁食，早餐加胶囊性安慰剂（蔗糖）或MSG(5克)，进行盲试。重复3次实验GehaRSetal.,JAllergyClinImmunol

106:973-80,2000SYMPTOMSRATED:症状表现GeneralWeakness虚弱MuscleTightness肌肉紧张MuscleTwitching肌肉酸痛Flushing脸颊发红Sweating盗汗BurningSensation灼感Headache-migraine偏头痛Chestpain胸闷Palpitations心悸Numbness-Tingling发麻GehaRSetal.,JAllergyClinImmunol

106:973-80,2000ProtocolAResults:实验A结果n=50:≥2symptomswithMSG&0/1withplacebo.

MSG组超过2种症状出现+安慰剂组1个n=19:≥2symptomswithMSG&

placebo.超过2种症状出现，味精和安慰剂n=17:≥2symptomswithplacebo&0/1withMSG.安慰剂组超过2种症状出现+MSG组1个n=44:0or1symptomswithMSG&placebo.

没有或1种症状出现：MSG+安慰剂GehaRSetal.,JAllergyClinImmunol

106:973-80,2000ProtocolBResults:实验B结果n=86fromAhad≥2symptomswithatreatment(blinded:placeboorMSG),andincludedinB.69completed.对2种症状进行治疗（双盲：安慰剂或MSG）Overnightfast,challengewith0,1.25,2.5or5gMSG.禁食过夜，按0，1.25，2.5或5克MSG看结果GehaRSetal.,JAllergyClinImmunol

106:973-80,2000n=19/69reported≥2symptomsto5gMSGbutnotplacebo.19/69例报道，5克MSG下有超过2种症状出现，没有安慰剂n=14/19thesamesymptomsoccurredinBasinA.14/19例中同样症状出现，类似于A实验Hence,14/130showedreproducibleresponseto5gMSG.因此，14/130表现出对5克MSG的可重复性反应ProtocolCResults:实验C结果GehaRSetal.,JAllergyClinImmunol

106:973-80,20001995FASEBMSGPanel:

3placebo-MSGchallengesmustgivesamepositiveresponsetoMSG,noresponsetoplacebo.GiveMSGincapsules.1995年美国实验生物学联合会味精组：3种安慰剂-味精治疗必须引起同样的对味精的阳性反应，对安慰剂没有反应，味精应该以胶囊的形式给予。n=19had≥2symptomsin

A&B

withMSG&nosymptomswithplacebo.n=12agreedtobestudied.N=19时，实验A和B的味精组都有超过2种症状出现，安慰剂组没有症状出现，n=12时，实验一致。ProtocolCResults:实验C结果GehaRSetal.,JAllergyClinImmunol

106:973-80,2000TwoseparatetestsofMSG(5g)vsplacebo.分开测试味精（5克）和安慰剂n=2/12had≥2symptomswithMSG&nonewithplacebo;butsymptomswerenotthesame.n=2/12，味精组超过2种症状出现，安慰剂组没有症状出现，但症状不同。n=0/130metFASEBcriteriaforMSGsensitivityn=0/130时符合FASEB的MSG过敏性实验标准GehaRSetal.,JAllergyClinImmunol

106:973-80,2000CONCLUSION:

Usingcriteriaestablishedbythe1995FASEBpanel,

none

oftheindividualswhoclaimedasensitivitytoMSGactuallyshowedthissensitivitywhentestedunderblindedconditions.结论：根据1995年美国实验生物学联合会（FASEB）制定的标准，对那些声称味精过敏的个体进行双盲试验表明他们未表现出敏感性。CRSSymptomsinHumans

人体的MSG症状Asthma:EarlystudiesclaimingthatMSGinducesasthmainasthmapatientshavenotbeenconfirmedinrecentstudiesinvolvinggreaternumbersofpatients.哮喘：早期研究声称味精会导致哮喘病人病情发作，但近期众多数量病人的研究中未得到证实StevensonDD.Monosodiumglutamateandasthma.JNutr

130:1067S-1073S,2000味精和哮喘2000年营养学杂志.MSGSymptomsinHumans

人体的MSG症状Urticaria:65subjectswi