營養(yǎng)與食品衛(wèi)生學(xué)詳解演示文稿

營養(yǎng)與食品衛(wèi)生學(xué)詳解演示文稿當(dāng)前第1頁\共有97頁\編于星期日\15點（優(yōu)選）營養(yǎng)與食品衛(wèi)生學(xué)當(dāng)前第2頁\共有97頁\編于星期日\15點3.合理營養(yǎng)（RationalDiet）通過合理的膳食和科學(xué)地烹調(diào)加工，能向機體提供足夠數(shù)量的熱能和各種營養(yǎng)素，并保證各種營養(yǎng)素之間的數(shù)量平衡，以滿足人體的正常生理需要，并保持人體健康。Nutrientsintakesmeettherequirementsofthebody5.膳食營養(yǎng)供給量(RecommendedDietaryAllowance，RDA)

是對各種人群提出的保證人體營養(yǎng)需要的膳食中應(yīng)含有的熱能和營養(yǎng)素的適宜量。Theaveragedailyamountofanutrientconsideredadequatetomeettheknownnutrientneedsofpracticallyallhealthypeople;agoalfordietaryintakebyindividuals.4.營養(yǎng)生理需要量（NutritionalRequirement）

是指能保持人體健康，達到應(yīng)有發(fā)育水平和能充分有效地完成各項體力和腦力活動所需要的熱能和各種營養(yǎng)素的必需量。Thelowestcontinuingintakeofenergyandnutrientsthatmaintainthespecifiedcriterionofadequacy(thatwillmaintainthespecificbiochemicalandphysiologicalfunctionsofthebody).當(dāng)前第3頁\共有97頁\編于星期日\15點Chapter1BasicNutrition

第一章營養(yǎng)學(xué)基礎(chǔ)

含量----16%——19%.更新：動態(tài)平衡，不斷更新，每天約3%，腸和骨髓最快。Section1Protein(蛋白質(zhì))一、蛋白質(zhì)（一）人體中蛋白質(zhì)：（二）功能：

1.機體構(gòu)成成分

2.構(gòu)成各種生理活性物質(zhì)和重要的生理功能

3.提供熱能

當(dāng)前第4頁\共有97頁\編于星期日\15點（三）Thefirststructure

蛋白質(zhì)(protein)

氨基酸（Aminoacid,AA）

非必需AA(nonessential-)：9種

半必需AA（條件必需AA）：2種

（semi-,orconditionally-）必需AA（essentional-）：9種

多肽（poly-）10AA以上寡肽（oligo-）4—10AA以下

3肽（tri-）3AA2肽（di-）2AA

肽(peptide)

當(dāng)前第5頁\共有97頁\編于星期日\15點

二、氨基酸和必需AA(essentialaminoacid,EAA)

1.種類：20種

(1)必需AA（EAA）(2)非必需氨基酸（NEAA）

(3)半必需氨基酸(semi-EAAorconditionalEAA)半胱酸（Cysteine）——蛋氨酸（Methionine）酪氨酸（Tyrosine）——苯丙氨酸（Phenylalanine）2.必需氨基酸：人體不能合成或合成速度不能滿足機體需要，必需從食物中直接獲得的AA。Aminoacidsthatthebodycannotsynthesizeinamountsufficienttomeetphysiologicalneedsandhastoobtainthemfromfoods.

當(dāng)前第6頁\共有97頁\編于星期日\15點氨基酸英文氨基酸英文必需氨基酸非必需氨基酸異亮氨酸Isoleucine(Ile)丙氨酸Alanine(Ala)亮氨酸Leucine(Leu)精氨酸Arginine(Arg)賴氨酸Lysine(Lys)天門冬氨酸Asparticacid(ASP)蛋氨酸Methionine(Met)谷氨酸Asparagine(Asn)苯丙氨酸Phenylalanine(Phe)谷氨酰胺Glutamicacid(Glu)蘇氨酸Threonine(Thr)甘氨酸Glycine(Gly)色氨酸Tryptophan(Trp)脯氨酸Proline(Pro)纈氨酸Valine(Val)絲氨酸Serine(Ser)組氨酸*Histidine(His)天冬酰胺Asparagine(ASN)條件必需氨基酸半胱氨酸Cysteine(Cys)酪氨酸Tyrosine(Tyr)表1-1人體內(nèi)的氨基酸*組氨酸為嬰兒必需氨基酸，成人需要量可能較少。

摘自ModernNutritioninHealthandDisease,第9版,第14頁,1999。當(dāng)前第7頁\共有97頁\編于星期日\15點(三)氨基酸模式(AAPattern)和限制氨基酸(limitingAA)1.氨基酸模式(AAPattern)：

蛋白質(zhì)中各種必需氨基酸的構(gòu)成比例。當(dāng)前第8頁\共有97頁\編于星期日\15點氨基酸人體全雞蛋牛奶牛肉大豆面粉大米異亮氨酸4.03.23.44.44.33.84.0亮氨酸7.05.16.86.85.76.46.3賴氨酸5.54.15.67.24.91.82.3蛋氨酸+半胱氨酸3.53.42.43.21.22.82.3苯丙氨酸+酪氨酸6.05.57.36.23.27.23.8蘇氨酸4.02.83.13.62.82.52.9纈氨酸5.03.94.64.63.23.84.8色氨酸1.01.01.01.01.01.01.0表1-2幾種食物和人體蛋白質(zhì)氨基酸模式數(shù)據(jù)摘自營養(yǎng)與食品衛(wèi)生學(xué)，第3版，第9頁。當(dāng)前第9頁\共有97頁\編于星期日\15點2.限制氨基酸

（limitingaminoacid）：與人體蛋白質(zhì)模式比較，食物蛋白質(zhì)中含量相對較低的必需AA。Theessentialaminoacidfoundintheshortestsupplyrelativetotheamountneededforproteinsynthesisinthebody.FourAAaremostlikelytobelimiting:Lysine，Methionine，Threonine，Tryptophan.當(dāng)前第10頁\共有97頁\編于星期日\15點3.參考蛋白、完全蛋白和蛋白質(zhì)的互補作用參考蛋白用于測定食物蛋白質(zhì)質(zhì)量的標(biāo)準(zhǔn)蛋白。

ReferenceProtein:Astandardagainstwhichtomeasurethequalityofotherproteins.完全蛋白必需氨基酸模式與人體蛋白質(zhì)相對一致，能滿足機體蛋白質(zhì)合成需要的食物蛋白質(zhì)。

CompleteProtein:Adietaryproteincontainingalltheessentialaminoacidsinrelativelythesameamountsthathumanbeingrequired.(includinganimalproteinandsoyprotein)

Incompleteprotein蛋白質(zhì)互補將兩種或兩種以上的食物蛋白質(zhì)混合事用，使不同食物中必需氨基酸以多補少，從而提高膳食蛋白質(zhì)的營養(yǎng)價值。

ComplementaryProtein:Twoormoreproteinswhoseaminoacidsassortmentscomplementeachotherinsuchawaythattheessentialaminoacidsmissingfromonearesuppliedbytheother.當(dāng)前第11頁\共有97頁\編于星期日\15點幾種食物混合后蛋白質(zhì)的生物價食物BV混合比例小米-6737---31大米57324046大豆6416208豌豆4815------玉米60---40---牛肉（干）76------15混合后生物價---747389當(dāng)前第12頁\共有97頁\編于星期日\15點三、蛋白質(zhì)的消化、吸收和代謝

（一）消化和吸收

（digestionandabsorption）

當(dāng)前第13頁\共有97頁\編于星期日\15點GastricJuice

:1.Acid–denaturation2.Pepsin--nothighlyspecificbutpreferentialattackonbondsadjacenttoaromaticAAandleucine.3.Carboxypeptidase--terminalaromaticorbranch-chained;arginineorlysine;neutral-

dietary

Protein

Panc-elastase(彈性蛋白酶)--arometicAAreatic

trypsin(胰蛋白酶)--NH2-

juice

chymotrypsine(糜蛋白酶)--lysine,arginine

dipeptide,tripeptideandfreeAAabsorbedthroughthemucosalcellsofsmallintestinepeptidase

throughthreeactivefreeAAtransportsystemsneutral-,basic-andacidic-.Liverandotherorgans當(dāng)前第14頁\共有97頁\編于星期日\15點（二）

代謝與氮平衡(metabolismandnitrogenbalance)1.代謝攝入蛋白質(zhì)90克

消

化

道(30%)肌肉(50%)器官體液其它機體蛋白質(zhì)氨基酸池糞便10g(1.6gN)尿75g(12gN)其它5g(0.8gN)(20%)腸道內(nèi)源性蛋白質(zhì)70g消化、吸收蛋白質(zhì)150g圖1-1蛋白質(zhì)代謝及氮平衡當(dāng)前第15頁\共有97頁\編于星期日\15點2.氮平衡（Nitrogenbalance）必要的氮損失（obligatorynitrogenlosses）(2)氮平衡：B＝I－（U＋F＋S）Positive

nitrogen

balanceNin>NoutNin=NoutNitrogen

equillibriumNegativenitrogen

balanceNin<Nout當(dāng)前第16頁\共有97頁\編于星期日\15點四、食物蛋白質(zhì)營養(yǎng)學(xué)評價

(1)真消化率（true-）(一)蛋白質(zhì)含量(content）(2)表觀消化率（apparent-）:(二)蛋白質(zhì)消化率(digestibility)當(dāng)前第17頁\共有97頁\編于星期日\15點(三)蛋白質(zhì)利用率（utilization）1.Biologicalvalue,BV:生物價

Theamountofproteinnitrogenthatisretainedforgrowthandmaintenance,

expressedasapercentageoftheproteinnitrogenthathasbeendigestedandabsorbed.

Todeterminetheactualvalueofanabsorbedproteinasitisusedbythebody.當(dāng)前第18頁\共有97頁\編于星期日\15點2.NetProteinUtilization,NPU蛋白質(zhì)凈利用率

Theamountofproteinnitrogenthatisretainedfromagivenamountofproteinnitrogeneaten.Todeterminetheaminoacidcompositionanddigestibilityofatestprotein.當(dāng)前第19頁\共有97頁\編于星期日\15點

3.ProteinEfficiencyRatio,PER:蛋白質(zhì)功效比值A(chǔ)measureofproteinqualityassessedbydetermininghowwellagivenproteinsupportsweightgainingrowingrats.

Usedtoestablishtheproteinqualityforinfantformulasandbabyfoods.當(dāng)前第20頁\共有97頁\編于星期日\15點4.AminoAcidScore,AAS氨基酸評分

ThelowestscoreisthescoreoflimitingAAwhichistheAASoftheprotein.

Amethodofevaluatingproteinqualitybycomparingatestprotein’saminoacidpatternwiththatofareferenceprotein;sometimescalledchemicalscoring.當(dāng)前第21頁\共有97頁\編于星期日\15點表1-4幾種食物和不同人群需要的氨基酸評分模式氨基酸人群（mg/g蛋白質(zhì)）1歲以下2~5歲10~12歲成人食物(mg/g蛋白質(zhì))雞蛋牛奶牛肉組氨酸26191916222734異亮氨酸46282813544748亮氨酸93664419869581賴氨酸66584416707889蛋氨酸+半胱氨酸42252217573340苯丙氨酸+酪氨酸726322199310280蘇氨酸4334289474446纈氨酸55352513666450色氨酸171195171412總計460339241127512504479摘自WTOTechnicalReportSeries724,第12頁,1985年。當(dāng)前第22頁\共有97頁\編于星期日\15點表1-5常見幾種食物蛋白質(zhì)質(zhì)量食物BVUPN(%)PERAAS全雞蛋94843.921.06全牛奶87823.090.98魚83814.551.00牛肉74732.301.00大豆73662.320.63精制面粉52510.600.34大米63632.160.59土豆6760－－0.48摘自“營養(yǎng)與食品衛(wèi)生學(xué)”，第3版，第11頁。當(dāng)前第23頁\共有97頁\編于星期日\15點5.ProteinDigestibilitycorrectedAAS,PDCAAS:

（經(jīng)消化率校正的氨基酸評分）

AmeasureofproteinqualityassessedbycomparingtheaminoacidscoreofafoodproteinWiththeaminoacidrequirementsofpreschool-ageChildrenandthencorrectingforthetruedigestibilityoftheprotein;RecommendedbytheFAO/WHOandusedtoestablishproteinqualityoffoodsfordailyvaluepercentageonfoodlabels.當(dāng)前第24頁\共有97頁\編于星期日\15點表1-6幾種食物蛋白質(zhì)的PDCAAS食物蛋白PDCAAS食物蛋白PDCAAS酪蛋白1.00斑豆0.63雞蛋1.00燕麥粉0.57大豆分離蛋白0.99花生粉0.52牛肉0.92小扁豆0.52豌豆粉0.69全麥0.40菜豆0.68摘自UnderstandingNutrition,第7版，第215頁，1996年。當(dāng)前第25頁\共有97頁\編于星期日\15點

五、蛋白質(zhì)營養(yǎng)不良

（protein-energymalnutrition,PEM）

Kwishiorkor:AGhanaianwordmeaning“theevilspiritthatinfectsthefirstchildwhenthesecondchildisborn”.Thesecondchildsuddenlyswitchedfromnutrientdense,protein-richbreastmilktoastarchy,protein-poorcereal,soonbeginstosickenanddie.

Marasmus:Aseveredeprivationoffoodoveralongtime(chronicPEM)andthereforeiscausedbyaninadequateenergyandproteinintake(andbyinadequateessentialfattyacids,vitamins,andmineralsaswell).當(dāng)前第26頁\共有97頁\編于星期日\15點蛋白質(zhì)營養(yǎng)不良KwashiorkorMarasmus當(dāng)前第27頁\共有97頁\編于星期日\15點Marasmus

Kwashiorkor

Infancy(lessthan2yr)

olderinfantsandyoungchildren(1-3yr)

Developsslowly;chronicPEMrapidonset;acutePEM

Severeweightloss

someweightloss

Severemusclewasting,withfatSomemusclewasting,withretentionofsomebodyfatGrowth:<60%weight-for-agegrowth:60%-80%weight-for-age當(dāng)前第28頁\共有97頁\編于星期日\15點NodetectableedemaedemaNofattyliverenlargedfattyliverAnxiety焦急,apathy淡漠

apathy,misery痛苦,irritability易怒,sadnessGoodappetitepossiblelossofappetiteHairissparse,thinanddry;Easilypulledouthairisdryandbrittle;easilypullout;changescolor;becomesstraightSkinisdry,thin,andeasilywrinklesskindevelopslesion當(dāng)前第29頁\共有97頁\編于星期日\15點3.高蛋白質(zhì)膳食過多的危害

（problemsofexcessprotein）

AdultBoneLoss(Osteoporosis骨質(zhì)疏松):Calciumexcretionrisesasproteinintakeincreases.Recommen-dationofcalcium-to-proteinismorethan20(mg)to1(g).Cancer:populationstudiessuggestacorrelationbetweenhighintakesofanimalproteinandsometypecancer(cancerofcolon,breast,kidneys,pancreas,andprostate)GainWeight:Protein-richfoodsareoftenfat-richfoods.

Others.HeartDisease:Foodsrichinanimalproteintendtoberichinsaturatedfatsandcholesterol;homocystei（高半胱氨酸）maybeanindependentriskfactorforheartdisease.當(dāng)前第30頁\共有97頁\編于星期日\15點六、蛋白質(zhì)供給量和食物來源

（DRIsandFoodsource）

RNI:1)數(shù)量2）質(zhì)量(優(yōu)質(zhì)蛋白質(zhì))Assessmentofproteinnutritioninhumanbody(1)Serumalbumin:35-50g/L(2)Serumtransferritin:2.2-4g/L(3)Retinol-bindingprotein:26-76mg/L(4)Thyroxine-binding-albumin:280-350mg/L3.FoodSource:animalandplantfoods.

MilkandSoybeen當(dāng)前第31頁\共有97頁\編于星期日\15點中國居民膳食蛋白質(zhì)的推薦攝入量:RNI與RDAAge(year)RNI（2000）RDA（1988）manwomanmanwoman0~1.5~3.0g/kg.bw.2.0~4.0g/kg.bw.0.5~1~353535352~404040403~454545454~505050455~555555506~555555557~606060608~656565609~6565656510~70657065當(dāng)前第32頁\共有97頁\編于星期日\15點RNI與RDA：續(xù)表Age(year)RNI（2000）RDA（1988）manwomanmanwoman11~757570~8070~8014~858080~9080輕7565807018~中80709080重908010090孕期早+5中+15+15晚+20+25乳母+20+2560~75657565當(dāng)前第33頁\共有97頁\編于星期日\15點Section2Lipids(脂類

)固醇類,sterols：脂類甘油三脂,triglycerides：磷脂,phospholipids99%inbody,95%infood99%inbody,95%infood一、脂類的分類Classification當(dāng)前第34頁\共有97頁\編于星期日\15點一、脂類的功能(function)

Structure：1glycerol＋3fattyacidsFunction（一）triglycerides,甘油三脂(TG)當(dāng)前第35頁\共有97頁\編于星期日\15點(1)triglyceridesinthebody:

A:Storingandprovidingthebodywithenergy:1g9.46kcal(兩個特點）B:Thelayeroffatbeneaththeskinhelpskeepthebodywarm(insulatingthebody)C:ProtectingandproppinguptheorgansinthebodyD:Helpingthebodyuseitstwootherenergynutrients—carbohydrateandprotein(sparingprotein)E:TheveryimportantcompositionofthebodyF:Incretion:leptin,TNF-α,IL-6,IL-8,adiponectin,resistin,estrogen,Insulin-likegrowthfactor(IGF),angiotensinogen(血管緊張素),IGFbindingprotein3,plasminogenactivatorinhibitor(PAI,纖維蛋白溶酶原激活因子抑制物)當(dāng)前第36頁\共有97頁\編于星期日\15點(2).Triglyceridesinthefoods:

A:Providingbodywithenergyandessentialfattyacid.B:Improvingthecolor,flavor,tasteandshapeoffoods.C:Becausedietaryfatcausesthestomachtoemptymoreslowlythaneithercarbohydrateorprotein,itimparts

satietyandsatisfaction.D:Tosupplybodywithfat-solublevitamins

andaidintestinalabsorptionofthem.當(dāng)前第37頁\共有97頁\編于星期日\15點(3).riskofhigh-fatdiet

Heartdisease:Foodsaturatedfat(especially12,14,16carbons)raisesbloodcholesterol

dramatically,whichcausesheartattackorstroke.Obesity肥胖:High-fatdiettendtostorebodyfatefficiently.

(3)Cancer:Prostatecancerisastrongassociationwithfat;Breastcancerisalittleornoassociationwithdietfat.

(4)Riskfromtrans-fattyacids:TheyraiseLDLandlowerHDL.

當(dāng)前第38頁\共有97頁\編于星期日\15點(二)fattyacids,脂肪酸(FA)

chainlength:long-chain(10~14carbonsormore)medium-chain(6or8--)short-chain(2—4or2—6)Saturation（飽和度）:saturatedFA(SFA)monounsaturatedFA(MUFA)polyunsaturatedFA(PUFA)position

ofdoublebond:“n”or“ω”“n-3”:theinitialdoublebondsituatedbetweenthethirdand4thcarbonatomsfromthemethylend.“n-6”:theinitialdoublebondisbetweenthe6and7isomericforms

異構(gòu)體:cis順式；trans反式(1)Classification當(dāng)前第39頁\共有97頁\編于星期日\15點(2).Essentialfattyacid,必需脂肪酸(EFA)

Definition:Classification:

(1)linoleicacid(亞油酸).C18:2,n-6(2)α-linolenicacid（α

–亞麻酸）.C18:3,n-3

Fattyacidsneededbythebody,butnotmadebyittomeetphysiologicalneeds.當(dāng)前第40頁\共有97頁\編于星期日\15點SynthesizeofMUFAinbody

linoleicacid(C18:2,n-6)α-linolenicacid(C18:3,n-3)

6去飽和酶

γ-linolenicacid(C18:3,n-6)十八碳四烯酸(C18:4,n-3)碳鏈延長酶bi-homotypeγ-linolenic二十碳四烯酸(C20:4,n-3)acid(C18:3,n-6)

5去飽和酶arachidicacid(AA)timnodonicacid(EPA)(C20:4,n-6)(C20:5,n-3)碳鏈延長酶二十二碳四烯酸(C22:4,n-6)clupanodonicacid(C22:5,n-3)

4去飽和酶二十二碳五烯酸(C22:5,n-6)docosahexenoicacid(DHA)(C22:5,n-3)當(dāng)前第41頁\共有97頁\編于星期日\15點FunctionofEFATomaintainthestructuralpartsofcellmembranes.(itisapartofphospholipids)

Usedtosynthesizemanyhormonelikesubstances-eicosanoids（二十烷）:prostaglandins(PG,前列腺

素)，Thromboxane(TXA,凝血惡烷)，leukotrienes(LT,白三烯),hydroxyfattyacids,andlipoxins(脂素).

(3)Lowerbloodcholesterolandriskofheartattackorstroke,especiallyEPA(eicosapentaenoicacid)andDHA(docosahaxaenoicacid).

Theymodulatecardiovascular,pulmonary,immune,reproductive,andsecretoryfunctionsinmanycells.當(dāng)前第42頁\共有97頁\編于星期日\15點DeficiencyofEFAAffectdevelopment,production,liver,kidney,nerve,vision,andskin.

當(dāng)前第43頁\共有97頁\編于星期日\15點(三)磷脂(phospholipid)1.Structure：

Itconsistofaglycerolbackbonewithoneortwoattachedfattyacids,plusadifferentstructurethatincludesaphosphategroupattachedtotheotherhydroxylgroup(s).Themostimportantmemberislecithins（卵磷脂）.當(dāng)前第44頁\共有97頁\編于星期日\15點2.Function

(1)Importantconstituentsofcellmembranes.

Theythusallowfat-solublesubstances,includingvitaminsandhormones,topasseasilyinoroutofcells.(3)Asemulsifiers（乳化劑）inthebodyorfoodmanufacturers.(4)Tosupplybodywith9kcaloriespergram.(5)Healthfunction:differentpoints.當(dāng)前第45頁\共有97頁\編于星期日\15點(四)固醇(Sterols)

1.Structure:

Asamemultiple–ringwithdifferentsidegroupsattached.Cholesterolisthemostimportant.當(dāng)前第46頁\共有97頁\編于星期日\15點

2.Function:

Essentialtothestructureandfunctionofcells,especiallythecellmembrane(about90%oftotalbodycholesterol).Cholesterolistheoriginalmaterialforsynthesisofmanyvitallyimportantbodycompoundssuchasbile,sexhormones,adrenalhormone,andvitaminD.3.Harmfuleffects:

Itformsdeposits(沉積物)inthearterywallswhichleadtoatherosclerosis(動脈粥樣硬化)---adiseasethatcausesheartattacksandstrokes.當(dāng)前第47頁\共有97頁\編于星期日\15點二、脂類代謝（metabolism）

mouth

salivarygland（唾液腺）---lipase（脂肪酶）:Itplaysasmallroleindigestioninadults,butefficientlydigeststheshort-andmedium-chainfattyacidsofmilkininfants.Stomach

Stomach’schurning

攪拌actionmixesfatwithwaterandacid.Agastriclipasehydrolyzesaverysmallamountoffat.當(dāng)前第48頁\共有97頁\編于星期日\15點Smallintestine

emulsificationoffatbybile

PancreaticlipaseIntestinallipase

bile

trappedbydietaryfibersandcarriedoutofthebodywiththefecesReabsorbedintothebloodliverGallbladder(膽囊)Monoglyceride,fattyacidsandglycerol

Long-chainfattyacidsMonoglyceridesGlycerol,short-andmedium-chainFattyacidsabsorbeddirectlyintobloodMerge（結(jié)合）intomicelles(微膠粒)

當(dāng)前第49頁\共有97頁\編于星期日\15點Merge（結(jié)合）intomicelles

(微膠粒)

Easilydiffuse(擴散)intotheintestinalcellsandreassembled(重新合成)intonewtriglycerides.Withcholesterolandphospholipids,ChylomicronswithintheintestinalcellsAbsorbedintolymph,thenintobloodCellsalloverthebodyremovelipidsfromthechylomicrons（乳糜微粒）astheypassby,andmakethemsmallerandsmaller.protein

Livercellscollectthechylomicronremnants（殘體）,andpackthemwithlipids,cholesterolandproteinsasVLDLwhichwilltravelthroughthebodyintheblood.當(dāng)前第50頁\共有97頁\編于星期日\15點HDLmadeinthelivercarrycholesterolsandphospholipidsfromthecellsbacktotheliver.

TheylosetriglyceridesandgathercholesterolfromOtherlipoproteinscirculatingthroughthebloodstreamAndbecomeLDL當(dāng)前第51頁\共有97頁\編于星期日\15點Metabolismofcholesterol當(dāng)前第52頁\共有97頁\編于星期日\15點三、FoodsourceandRDA

脂類的食物來源及供給量1.Foodsource:1).Animalfat:plentyofSFA

2).Vegetableoil:plentyofMUFA當(dāng)前第53頁\共有97頁\編于星期日\15點LinoleicAcid(n-6)

leafyvegetables,seeds,nuts,grains,vegetableoil(corn,safflower紅花,soybean,cottonseed,sesame芝麻,sunflower)ArachidonicAcid(n-6)

meats,canbesynthesizedfromlinoleicacid

linolenicacid（n-3）

fatsandoil(soybean,walnut胡桃,wheatgerm)EPAandDHA(n-3)

Humanmilk,shellfishandfish(mackerel鮐魚,tuna金槍魚,salmon大麻哈魚,sturgeon鱘魚,herring鯡魚,trout鱒魚,sardines沙丁魚),canbemadefromlinolenicacid.

當(dāng)前第54頁\共有97頁\編于星期日\15點當(dāng)前第55頁\共有97頁\編于星期日\15點2.DRIs:basicprinciple

percentageoftotaldietaryenergy：20%---30%SFA/totaldietaryenergy<10%n-6/totaldietaryenergy≥3%,n-6∶n-3＝4∶1Cholesterol<300mg/d3.Substituteoffat

蔗糖聚酯sucrosepolyester,Olestra燕麥素Ostrim

當(dāng)前第56頁\共有97頁\編于星期日\15點AIsofdietaryfat(percentageoftotaldietaryenergy)注1：SFA為飽和脂肪酸；MUFA為單不飽和脂肪酸；PUFA為多不飽和脂肪酸注2：n-6/n-3表示n-6系列不飽和脂肪酸與n-3系列不飽和脂肪酸的比例AgeyearFat%SFA%MUFA%PUFA%n-6/n-3Cholesterolmg0~45~504∶10.5~35~404∶12~30~354~6∶17~25~304~6∶114~25~30<108104~6∶118~20~30<1010104~6∶1<30060~20~306~8108~104∶1<300當(dāng)前第57頁\共有97頁\編于星期日\15點Section3.carbohydrate

碳水化合物一、分類與食物來源Classificationandfoodsource

單糖(monosaccharide)雙糖(disaccharide)寡糖(oligosaccharide)多糖（polysaccharide）當(dāng)前第58頁\共有97頁\編于星期日\15點（一）單糖(monosaccharide)1.Glucose:D-andL-.Alittleinthenaturalfoods.

2.Fructose（果糖）:

主要存在于水果和蜂蜜中，人工制造的玉米糖漿中含40%-90%。

Itisfoundinfruits,honey(abouthalffructoseandhalfglucose),andhigh-fructosecornsyrupwhichisusedintheproductionofsoftdrinks,frozendesserts,andconfections(糖果和蜜餞等).InmostAmericandiets,fructoseaccountsforabout8%-10%oftotalenergyintake.當(dāng)前第59頁\共有97頁\編于星期日\15點3.Galactose（半乳糖）：以乳糖形式存在于天然食物中。

Itisnotusuallyfoundfreeinnatureinlargequantities,butrathercombineswithglucosetoformlactose.4.Others:

ribose(核糖)，deoxyribose(脫氧核糖)、arabinose(阿拉伯糖)、xylose(木糖)、

sugaralcohols(糖醇)：sorbitol（山梨醇）、mannitol（甘露醇）、dulcitol（衛(wèi)矛醇）、inocitol（肌醇）

當(dāng)前第60頁\共有97頁\編于星期日\15點(二)雙糖（disaccharide）

1.Sucrose(蔗糖)：葡萄糖＋果糖，foundinsugarcane（甘蔗）andsugarbeets（甜菜）2.Maltose（麥芽糖）：葡萄糖＋葡萄糖，淀粉水解產(chǎn)物3.Lactose（乳糖）：葡萄糖＋半乳糖，乳及乳制品中

4.Trehalose(海藻糖)：葡萄糖＋葡萄糖，真菌（fungus）及細菌中當(dāng)前第61頁\共有97頁\編于星期日\15點(三)寡糖（oligosaccharide）：

3-10單糖組成。有些具有重要的生理功能

(四)多糖（polysaccharide）

1.糖原(glycogen)：

動物淀粉2.淀粉（starch）：直鏈淀粉(amylose)---老化,支鏈淀粉(amylopectin)---胡化。3.纖維（fibre）

Nonstarchpolysaccharidesinplantfoodsthatarenotdigestedbyhumandigestiveenzymes,butsomearedigestedbyGItractbacteria.Fiberinfoodsisalsocalleddietaryfiber.

definition:

當(dāng)前第62頁\共有97頁\編于星期日\15點

Insolublefiber

Cellulose（纖維素）:

Itistheprimaryconstituentofplantcellwallsandthereforeoccursinallvegetables,fruitsandlegumes（豆類）.Hemicellulose（半纖維素）:

Itisthemainconstituentofcerealfiber.Themanybackbonesandsidechainsmakethehemicelluloseadiversegroup;somearesoluble,manyofthemareinsoluble.Lignin（木質(zhì)素）：Itisanonpolysaccharidefiber.Itoccursinthewoodypartsofvegetablesuchascarrotsorthesmallseedsoffruitssuchasstrawberries.ligninhemicellulose當(dāng)前第63頁\共有97頁\編于星期日\15點

solublefiber

(1)Pectins（果膠）：Itisβ-1,4-D-galacturonicacidpolymersmethylate(被甲酯化至一定程度的半乳糖醛酸多聚體).Commonlyfoundinvegetablesandfruits(especiallycitrus柑橘andapples).Pectinsmaybeisolatedandusedbythefoodindustrytothickenjelly,becausetheyreadilyformgelsinwater.(2)Gumsandmucilages（樹膠和粘膠）：Gumsarecomposedofvariousmonosaccharidesandtheirderivatives.Gumssuchasgumarabic(阿拉伯膠)areusedasadditivesbythefoodindustry.Mucilagesaresimilartogumsinstructure.Theyincludeguar（瓜拉膠）,whichareaddedtofoodasstabilizers.當(dāng)前第64頁\共有97頁\編于星期日\15點Foodsourceofdietaryfiber當(dāng)前第65頁\共有97頁\編于星期日\15點二、碳水化合物的功能Function

1.Functionofcarbohydrateinbody1).Componentofcellsandtissues:glycoprotein（糖蛋白）andglycolipid（糖脂）,mucin（粘蛋白）,andDNA,RNA.2).Storingglucoseasglycogenandusingitforenergy

Theliverstoresone-thirdofthebody’stotalglycogen.Whenbloodglucosefalls,thelivercellsdismantle(拆除，釋放)theglycogenintosinglemoleculesofglucoseandreleasethemintothebloodstreamtobeusedbycentralnervoussystemandotherorgans.Musclecellscanalsostoreglucoseasglycogen(theothertwo-thirds),buttheyuseitjustforthemselvesduringexercise.當(dāng)前第66頁\共有97頁\編于星期日\15點3).

Sparringproteinfromuseasenergysource（節(jié)約蛋白質(zhì)作用）

If

bodycannotconsumeenoughcarbohydratetoyieldglucose,itisforcedtomakeglucosefromprotein(thisprocessistermedglyconeogenesis糖異生),becausefatsgenerallycannotbeconvertedintoglucose.Soenoughcarbohydratescansparebodyproteinwhichcanbeusedtomakebodytissuesandtoperformothervitalprocesses.(即足夠的碳水化物可以使體內(nèi)蛋白質(zhì)不被分解作為熱能而消耗的作用)sparingproteinaction?當(dāng)前第67頁\共有97頁\編于星期日\15點4).Preventingketosis（抗生酮作用）

A

lowcarbohydrateintake,withtheresultingdeclineinreleaseoftheinsulin,leadstoincompletebreakdownoffattyacidsintheliver’smetabolicpathwayandtoformationofketones.

Soenoughcarbohydrateisnecessaryforthecompletemetabolismoffatsinthebody.當(dāng)前第68頁\共有97頁\編于星期日\15點2.Functionofcarbohydrateinfoods

1).Supplyingenergy

Carbohydrateisthecheapestandbroadestfoodenergysourceintheworld(4kcal/g).

2).Imparting(把---給予)color,flavortofoodsandchangingtheirshape.

Thesugaristhemostimportantsweetener.Modifiedstarchisrichinamylopectin(支鏈淀粉)andmaymakefoodstablewhichisusedinbabyfoods,saladdressings,andinstant(速溶)puddings.當(dāng)前第69頁\共有97頁\編于星期日\15點幾種糖及糖醇的相對甜度名稱相對甜度名稱相對甜度乳糖0.2果糖1.2-1.8麥芽糖0.4山梨醇0.6葡萄糖0.7甘露醇0.7蔗糖1.0木糖醇0.9摘自：PerspectiveinNutrition，第三版，第77頁，1996。當(dāng)前第70頁\共有97頁\編于星期日\15點3).Supplyingdietaryfiber

(1).Weightcontrol:Fiberslowstherateoffoodleavingthestomachanddrawwaterintotheintestine,whichcandelaythestomach’semptyingandglucoseabsorption.(2).Lowingserumcholesterol:Solublefibercanbindwithbileandfoodcholesterolwhichwoulddecreasefatandcholesterolabsorption;ThenliversynthesizesmorebilefromcholesterolandexcretedintheGItract,whichreducesbloodcholesterolfurther;Theshort-chainfattyacidsresultingfrombacterialdegradationsolublefiberalsoreducecholesterolsynthesisintheliveroncethesefattyacidsareabsorbedandentertheliver.FunctionofdietaryfiberThesixthnutrient當(dāng)前第71頁\共有97頁\編于星期日\15點(3)Makingeliminationoffecesmucheasier

Toolittlefibereatingmakesstoolsmallandhard,andconstipation(便秘)mayresultwhichcanforceonetoexertexcessivepressureinthelargeintestineduringdefecation（排便）.Thishighpressurecanformmanysmallpouches(囊)onthelargeintestinewallcalleddiverticula(憩室)andhemorrhoid(痔瘡).

Enoughfibercanmakestoollargeandsoftbecauseitattractswater.Thelargesizestimulatestheintestinalmuscles,whichaidselimination.當(dāng)前第72頁\共有97頁\編于星期日\15點(4)playingakeyroleinpreventingcoloncancerofthelargeintestine

Itmaybeduetothefermentationofresistantstarch(抗性)fiber,inthecolon,whichlowersthepH.AdecreasedpHinthecolonisassociatedwithdecreasedcoloncancerrisk.Itisunclearwhethertheprotectionderivesfromthefiberorthevitamins.

Fibermayhelppreventcoloncancerbydiluting,binding,andrapidlyremovingpotentiallycancer-causingagentsfromthecolon.當(dāng)前第73頁\共有97頁\編于星期日\15點三、碳水化合物的消化吸收

DigestionandAbsorption1.Th