味精安全問題課件

Umami/MSG:SafetyIssues

味精的安全問題JohnD.Fernstrom,Ph.D.Professor-UniversityofPittsburghSchoolofMedicine匹茲堡大學醫(yī)學院教授ScientificAdvisor-IGTCIGTC科學顧問Outline內容綱要Briefreviewoforiginalissuesleadingtoexpressionofconcerninearly1970s

簡要回顧上世紀70年代初引起關注的安全問題Briefsummaryofsafetyviewsnow

簡單總結當前關于味精安全的觀點Examinationoftwogeneralissues兩大類問題Neurotoxicity神經毒性GeneralAdverseEffects(e.g.,MSGSymptomComplex)所有不良反應（如味精綜合癥）Conclusions

結論KwokRHM

Chinese-RestaurantSyndrome中國餐館綜合癥

NewEnglJMed

278:796,1968(letter)

1968年新英格蘭醫(yī)學雜志（通訊）FirstreportofadversesymptomsinhumansassociatedwiththeingestionofChinesefoodthatsuggestedapossiblelinktoMSG(aswellasmanyotheringredients).首例報道人體攝入中國食品后出現不適癥狀可能與所添加的味精有關（也可能是其他添加成分）Ananecdotalcase-report.單例報告（缺乏足夠科學依據）SchaumbergHHetal.

MonosodiumL-Glutamate:ItsPharmacology&RoleintheChineseRestaurantSyndrome

Science163:826-828,1969

谷氨酸單鈉的藥理學及其在中國餐館并發(fā)癥中的角色

《科學》163期，826-828頁，1969DefinedMSG"SymptomTriad“味精“三種并發(fā)癥狀”表現為Burning灼燒感FacialPressure面部緊張ChestPain胸痛Skeletalstunting骨萎縮Markedobesity明顯肥胖Sterility不育Hypothalamiclesions下丘腦損傷MSGINJECTED注射味精后OlneyJW.

BrainLesions,ObesityandOtherDisturbancesinMiceTreatedwithMonosodiumGlutamate.

SCIENCE164:719-721,1969.

小白鼠注射味精后出現大腦損傷，肥胖以及其他系統(tǒng)紊亂

1969年科學雜志ConventionalToxicologicdatabaseforreviewbyJECFAwasveryextensive,includingacute,subchronic&chronictoxicitystudiesinrats,mice&dogs,togetherwithstudiesonreproductivetoxicityandteratology供食品添加劑聯合專家委員會審查的常規(guī)毒性數據資料非常完整，包括大白鼠、小白鼠和狗的急性，亞慢性，慢性毒性研究以及遺傳性毒性和畸形學研究。TheSafetyEvaluationofMonosodiumGlutamateWalkerR,LupienJRJournalofNutrition130:1049S-1052S,2000.味精的安全評估2000年營養(yǎng)學雜志Neurotoxicity神經毒性研究DietaryMSG食用味精

Plasma(GLU)血漿（谷氨酸）上升

Brain(GLU)大腦（谷氨酸）上升

Neuronalexcitation&death神經興奮和死亡BarrierstoNeurotoxicity

GastrointestinalTractefficientlyusesingestedGLU(MSG)asE-source(95+%).胃腸道能有效地吸收95%以上的谷氨酸鈉作為能源GutisthusabarriertoGLUentryintoblood.腸道因此能阻止谷氨酸進入血液中Blood-BrainBarrierpreventsGLUpenetrationintobrain.血腦屏障阻止谷氨酸滲透到大腦OnlyveryhighoraldosesofMSGbygavagecanraiseplasmaGLUenoughtogetGLUintobrain只有灌喂大劑量的味精，才會致血漿中的谷氨酸含量升高，而進入到大腦MSGinfood

doesnothavethiseffect.食物中添加的味精不會有這種效果FernstromJDetal.JClinEndocrinolMetab

81:184-191,1996.1996年，臨床內分泌代謝雜志Adultmales(80kg)quicklyingestedMSG,12.7g(150mg/kg)

insolution.成年男子（體重約80公斤）能很快吸收溶液中12.7g（約150毫克每公斤）的味精TsaiP-J,HuangP-CMetabolism48:1455-1460,1999.Arrows=mealorsnack箭頭代表攝取的食物或點心Meals:0745,1215,1800h飲食時間：0745，1215，1800DailyMSGdose=100mg/kg:每日攝入味精量：100mg/kgBreakfast:15mg/kg早餐：15mg/kgLunch:40mg/kg午餐:40mg/kgDinner45mg/kg晚餐：45mg/kgDataaremeans±sem(n=10)數據：均值±標準差Blackcircle:noMSG黑圈表示不含味精Whitecircle:MSG.白圈表示含有味精

GLUinjectionipstimulatesPRLsecretioninratsDoesGLU(MSG)ingestionstimulatePRLsecretioninhumans?腹腔注射谷氨酸鈉會刺激小白鼠催乳素的分泌，它會對人體產生同樣的作用嗎？12.7goralloadofMSGinmalesubjects雄性研究對象12.7克口服PlasmaPRLinratsinjectedwithMSG(1000mg/kgip).From:TerryLCetal.BrainResearch217:129-142,1981.RatsHumansPlacentalBarriertoMaternalGlutamate胎盤屏障母體中的谷氨酸鈉SteginkLDetalAmJObstetGynecol122:70-78(1975)Monkeystudy.猴子實驗Highestdose(400mg/kgiv,opencircles)producedplasmaGLU70-timesnormal.BattagliaFC.JNutrition

130:974S-977S(2000)EffectoforalMSGloadingonbreastmilkfreeGLUconcentrationsinlactatingwomen哺乳婦女食用味精后母乳不會有谷氨酸鈉Lactatingwomeningested100mg/kgMSGincapsuleswithwater,andmilksamplesweretakenattheindicatedtimesthereafter.ThisdoseraisedplasmaGLUfrom45nmol/mltopeakvaluesofabout300nmol/mlin30-45min.From:BakerGLetal.,Factorsinfluencingdicarboxylicaminoacidcontentofhumanmilk.In:GlutamicAcid:AdvancesinBiochemistry&Physiology,FilerLJetal.,ed.NewYork,RavenPress,1979,pp.111-123.哺乳期女性加水攝入100mg/kg的膠囊，對其后特定時間的母乳樣品進行檢驗表明：這一劑量使得血液谷氨酸濃度在30-45分鐘內從45nmol/ml提高到峰值約300nmol/ml。From:BakerGLetal.,Factorsinfluencingdicarboxylicaminoacidcontentofhumanmilk.In:GlutamicAcid:AdvancesinBiochemistry&Physiology,FilerLJetal.,ed.NewYork,RavenPress,1979,pp.111-123.影響人體母乳二氨基酸濃度的因素谷氨酸：生物化學和生理學進展BrainIssues大腦問題

RelevancetohumanMSGingestion:有關人體攝入味精TheplacentablocksGLUtransferfrommaternalintofetalblood:FETALbrainissafe.胎盤會阻止谷氨酸從母體傳遞給胎兒：胎兒大腦不會受到影響B(tài)reastmilk(GLU)doesnotrisewhenmotheringestshigh-doseMSG:NEWBORN/INFANTbrainissafe.當母體攝入大劑量的味精母乳中的谷氨酸含量不會上升：新生兒的腦發(fā)育是安全的InfantmetabolizesGLUatsamerateasadult(Steginketal.,PediatricRes20:53-58,1986).嬰幼兒具有和成年人同樣的谷氨酸代謝的能力BrainIssues大腦問題

Thehumanbrainisunaffectedbytheveryhighplasma(GLU)followinghighdoseMSGintake攝入大量的味精導致的血漿中高谷氨酸含量不會對人體大腦產生影響NodoseofMSGhasyetbeengiventohumanshighenoughtoinduceCNSeffects.至今亦未發(fā)現食用味精會影響人體中樞神經系統(tǒng)CRS/Allergy

(MSGSymptomComplex)中國餐館綜合癥/過敏癥味精綜合癥StudyingMSGSymptomComplex

味精綜合癥研究Canreproduciblesymptomsbedefined?能定義這些重復性的癥狀么？Arereproduciblesymptomsdose-related?這些重復性癥狀與攝入劑量有關嗎?DoMSG-sensitiveindividualsexist?對味精敏感的個體存在嗎？SYMPTOMSATTRIBUTEDTOMSG:味精所致癥狀Burning,tightness,numbnessinupperchest,neckandface.發(fā)燒，身體發(fā)緊，胸腔上部發(fā)悶，脖子、面部發(fā)麻Dizziness,headache眩暈，頭疼Chestpain,palpitation胸口痛，心悸Weakness乏力Nausea,vomiting反胃嘔吐Bronchospasm(asthmatics)哮喘Hives(urticaria)麻疹MECHANISMSUNKNOWN機制未知Multicenter,double-blind,placebo-controlled,multiple-challengeevaluationofreportedreactionstomonosodiumglutamate.GehaRSetal.JAllergyClinImmunol

106:973-80,2000味精反應的多中心、雙盲、安慰劑控制、多重治療評估報告2000年過敏與臨床免疫學雜志ProtocolA:

130self-styledMSG-sensitiveindividuals.Fasted, challengeblindwithplaceboorMSG(5ginliquid).實驗A：130例自認為MSG過敏者，禁食，以安慰劑或MSG(5克液體)進行盲試。ProtocolB: Subjectshadpositiveresponseof≥2symptomsto

eitherorbothtreatmentsinA(i.e.,placeboresponders too).Fast,blindchallengewith0,1.25,2.5or5g MSG(inliquid).實驗B:對A中，出現陽性反應的實驗對象，超過2種癥狀（例如：對安慰劑反應也一樣）。禁食，以0，1.25，2.5或5克MSG(液體)進行盲試。GehaRSetal.,JAllergyClinImmunol

106:973-80,2000ProtocolC: Subjectshadpositiveresponseof≥2symptomsto5 gMSGbutnotplaceboinAorB.Fast,placebo(suc- rose)orMSG(5g),incapsules(blind).Dotwice.實驗C:對A和B中陽性反應的實驗對象-對5克MSG出現超過2種癥狀（對安慰劑沒有），禁食，以膠囊性的安慰劑（蔗糖）或MSG(5克)，進行盲試。重復實驗。ProtocolD: SubjectshadpositiveresponsetobothMSGchal- lengesinC.Fast,breakfast&placebo(sucrose) orMSG(5g),incapsules(blind).Dothreetimes.實驗D:對C中MSG治療出現陽性反應的實驗對象，禁食，早餐加膠囊性安慰劑（蔗糖）或MSG(5克)，進行盲試。重復3次實驗GehaRSetal.,JAllergyClinImmunol

106:973-80,2000SYMPTOMSRATED:癥狀表現GeneralWeakness虛弱MuscleTightness肌肉緊張MuscleTwitching肌肉酸痛Flushing臉頰發(fā)紅Sweating盜汗BurningSensation灼感Headache-migraine偏頭痛Chestpain胸悶Palpitations心悸Numbness-Tingling發(fā)麻GehaRSetal.,JAllergyClinImmunol

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

MSG組超過2種癥狀出現+安慰劑組1個n=19:≥2symptomswithMSG&

placebo.超過2種癥狀出現，味精和安慰劑n=17:≥2symptomswithplacebo&0/1withMSG.安慰劑組超過2種癥狀出現+MSG組1個n=44:0or1symptomswithMSG&placebo.

沒有或1種癥狀出現：MSG+安慰劑GehaRSetal.,JAllergyClinImmunol

106:973-80,2000ProtocolBResults:實驗B結果n=86fromAhad≥2symptomswithatreatment(blinded:placeboorMSG),andincludedinB.69completed.對2種癥狀進行治療（雙盲：安慰劑或MSG）Overnightfast,challengewith0,1.25,2.5or5gMSG.禁食過夜，按0，1.25，2.5或5克MSG看結果GehaRSetal.,JAllergyClinImmunol

106:973-80,2000n=19/69reported≥2symptomsto5gMSGbutnotplacebo.19/69例報道，5克MSG下有超過2種癥狀出現，沒有安慰劑n=14/19thesamesymptomsoccurredinBasinA.14/19例中同樣癥狀出現，類似于A實驗Hence,14/130showedreproducibleresponseto5gMSG.因此，14/130表現出對5克MSG的可重復性反應ProtocolCResults:實驗C結果GehaRSetal.,JAllergyClinImmunol

106:973-80,20001995FASEBMSGPanel:

3placebo-MSGchallengesmustgivesamepositiveresponsetoMSG,noresponsetoplacebo.GiveMSGincapsules.1995年美國實驗生物學聯合會味精組：3種安慰劑-味精治療必須引起同樣的對味精的陽性反應，對安慰劑沒有反應，味精應該以膠囊的形式給予。n=19had≥2symptomsin

A&B

withMSG&nosymptomswithplacebo.n=12agreedtobestudied.N=19時，實驗A和B的味精組都有超過2種癥狀出現，安慰劑組沒有癥狀出現，n=12時，實驗一致。ProtocolCResults:實驗C結果GehaRSetal.,JAllergyClinImmunol

106:973-80,2000TwoseparatetestsofMSG(5g)vsplacebo.分開測試味精（5克）和安慰劑n=2/12had≥2symptomswithMSG&nonewithplacebo;butsymptomswerenotthesame.n=2/12，味精組超過2種癥狀出現，安慰劑組沒有癥狀出現，但癥狀不同。n=0/130metFASEBcriteriaforMSGsensitivityn=0/130時符合FASEB的MSG過敏性實驗標準GehaRSetal.,JAllergyClinImmunol

106:973-80,2000CONCLUSION:

Usingcriteriaestablishedbythe1995FASEBpanel,

none

oftheindividualswhoclaimedasensitivitytoMSGactuallyshowedthissensitivitywhentestedunderblindedconditions.結論：根據1995年美國實驗生物學聯合會（FASEB）制定的標準，對那些聲稱味精過敏的個體進行雙盲試驗表明他們未表現出敏感性。CRSSymptomsinHumans

人體的MSG癥狀Asthma:EarlystudiesclaimingthatMSGinducesasthmainasthmapatientshavenotbeenconfirmedinrecentstudiesinvolvinggreaternumbersofpatients.哮喘：早期研究聲稱味精會導致哮喘病人病情發(fā)作，但近期眾多數量病人的研究中未得到證實StevensonDD.Monosodiumglutamateandasthma.JNutr

130:1067S-1073S,2000味精和哮喘2000年營養(yǎng)學雜志.MSGSymptomsinHumans

人體的MSG癥狀Urticaria:65subjectswi