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1、第一章第一章 营养学根底营养学根底碳水化合物碳水化合物Carbohydrates第一页，共六十二页。Main contents nDefinition of carbohydratesnClassification of carbohydratesnDigestion&absorption of CHOnFunctions of carbohydratesnDisorders related to CHO metabolismnDietary reference intakes of CHOs第二页，共六十二页。|Carbohydrates are one of the three macro
2、nutrient types that provide energy to our bodies.Carbohydrates contain carbon,hydrogen,and oxygen.碳水化合物：属三大能量营养素之一，主要由碳水化合物：属三大能量营养素之一，主要由碳、氢、氧构成。碳、氢、氧构成。一一、碳水化合物的定义、碳水化合物的定义 What are carbohydrates?|Carbohydrate can be abbreviated as“CHO.第三页，共六十二页。|We obtained carbohydrates predominantly from plant
3、foods such as fruits,vegetables,and grain.Why?第四页，共六十二页。Plants make carbohydrates through the process of photosynthesisEnergy from sunCarbon dioxide from airGlucose stored in plantWaterWater+Carbon dioxideGlucose光合作用光合作用第五页，共六十二页。二、碳水化合物的分类二、碳水化合物的分类Classification of carbohydratesCarbohydratesSimple
4、ComplexDisaccharidesMonosaccharidePolysaccharidesOligosaccharide寡糖寡糖单糖单糖双糖双糖多糖多糖第六页，共六十二页。HOHCH2OHHOHOHHOHHHGlucoseOHOHHOHHOHCH2OHCH2OHFructoseHOOHOHOHHHHHCH2OHGalactoseThe three most common monosaccharides.ALL of them contain identical atomsStructure of monosaccharides第七页，共六十二页。Monosaccharides-Gluc
5、ose葡萄糖葡萄糖|Glucose is the most abundant sugar molecule found in our diets and in our foods.|Glucose does not generally occur by itself in foods but attaches to other sugars to form disaccharides and complex carbohydrates.|In our bodies,glucose is the preferred source of energy for the brain.食物中最多的单糖，
6、但不以单独形式存在，常与食物中最多的单糖，但不以单独形式存在，常与其他糖形成双糖或多糖的形式存在，葡萄糖优先其他糖形成双糖或多糖的形式存在，葡萄糖优先为大脑提供能量。为大脑提供能量。第八页，共六十二页。Monosaccharides-Fructose果糖果糖|Fructose is also called fruit sugar.|Fructose is the sweetest natural sugar,occurs naturally in fruits and vegetables.Prefix第九页，共六十二页。Monosaccharides-Galactose半乳糖半乳糖|Gala
7、ctose does not occur alone in foods.It joins with glucose to create lactose,one of the disaccharides.第十页，共六十二页。Sweetest monosaccharides?The most abundant monosaccharides?The sweetest：fructoseThe most abundant：glucose 第十一页，共六十二页。Disaccharide双糖双糖|Disaccharide:A carbohydrate compound consisting of two
8、sugar molecules joined together.The three most common disaccharides found in foods are lactose乳糖乳糖,maltose 麦芽糖麦芽糖,and sucrose 蔗糖蔗糖.第十二页，共六十二页。Disaccharides Lactose乳糖乳糖GlucoseGalactoseLactose|Lactose:Consist of one glucose molecule and one galactose(半乳糖半乳糖 molecule.第十三页，共六十二页。DisaccharidesMaltose 麦芽糖
9、麦芽糖|Maltose:also called malt sugar,consist of two molecules of glucose.|It does not generally occur by itself in foods,but results as a by-product of digestion.Glucose第十四页，共六十二页。DisaccharidesSucrose蔗糖蔗糖vSucrose is composed of one glucose molecule and one fructose果糖果糖 molecule.vSucrose provides much
10、of the sweet taste found in honey,fruits,and vegetables.How about the Sucrose and fructose?vSweeter than lactose or maltose,why?第十五页，共六十二页。哪种双糖最甜哪种双糖最甜-麦芽糖，蔗糖，乳糖？麦芽糖，蔗糖，乳糖？麦芽糖麦芽糖-2个葡萄糖个葡萄糖蔗糖蔗糖-1个葡萄糖个葡萄糖+1个果糖个果糖乳糖乳糖-1个葡萄糖个葡萄糖+1个半乳糖个半乳糖蔗糖蔗糖第十六页，共六十二页。Oligosaccharide寡糖寡糖vOligosaccharide are composed of
11、 3 to 10 monosaccharides.vThe most common oligosaccharides arev raffinose 棉籽糖棉籽糖and stachyose水苏糖水苏糖.v They can not be degraded by enzymes in the small intestine,but can be broke down in the large intestine.第十七页，共六十二页。Polysaccharides多糖多糖Polysaccharides include starch淀粉淀粉,glycogen糖原糖原 and most fibers纤
12、维纤维.第十八页，共六十二页。PolysaccharidesStarchGlycogenFiber淀粉淀粉糖原糖原纤维纤维第十九页，共六十二页。Polysaccharide-Starch|Starch:A polysaccharide stored in plants and is the storage form of glucose in plants.淀粉是葡萄糖在植物中的贮存形式淀粉是葡萄糖在植物中的贮存形式|Excellent food sources of starch include?grains(wheat,rice,corn,oats,and barley),legumes(
13、peas,beans,and lentils),and tubers(potatoes and yams).第二十页，共六十二页。|Our bodies easily digest most starches，we call them digestible starch(可吸收淀粉可吸收淀粉.|根据其结构可分为直链淀粉根据其结构可分为直链淀粉amylose和支链和支链淀粉淀粉amylopectin，前者易使食物老化，后，前者易使食物老化，后者易使食物糊化者易使食物糊化gelatinization。第二十一页，共六十二页。|However,some starch in plants is not
14、 digestible and is called resistant starch抗性淀粉抗性淀粉.|抗性淀粉：指健康者小肠中不吸收的淀粉及其抗性淀粉：指健康者小肠中不吸收的淀粉及其降解产物。降解产物。第二十二页，共六十二页。|When our intestinal bacteria try to digest resistant starch,a fatty acid called butyrate is produced.|Consuming resistant starch may be beneficial because butyrate is suggested to reduc
15、e the risk of cancer.|豆科食物豆科食物LegumesLegumes含有的抗性淀粉比谷类、含有的抗性淀粉比谷类、蔬菜和水果多。蔬菜和水果多。Bean sproutGreen soybean第二十三页，共六十二页。|Glycogen:A polysaccharide stored in animals,including humans.|Very little glycogen exists in food.|Thus,glycogen is not a dietary source of carbohydrate.Polysaccharide-Glycogen糖原糖原第二十
16、四页，共六十二页。Which tissues are abundant in glycogen?We store glycogen in our muscles and liver.We can break down glycogen very quickly into glucose when we need it for energy.第二十五页，共六十二页。|Based on the water soluble ability,fiber can be classified into soluble fibers and insoluble fibers.|Insoluble fiber
17、s不溶性纤维不溶性纤维:cellulose纤纤维素维素,hemicellulose半纤维素半纤维素 and xylogen木质素木质素.|Soluble fibers可溶性纤维可溶性纤维:果胶果胶pectin)，树胶和粘胶树胶和粘胶.Polysaccharide-Fiber第二十六页，共六十二页。|膳食纤维膳食纤维dietary fiber：是指植物性食物：是指植物性食物或原料中糖苷键大于或原料中糖苷键大于3个，不能被人体小肠消个，不能被人体小肠消化和吸收，但对人体健康有意义的碳水化合化和吸收，但对人体健康有意义的碳水化合物。物。|膳食纤维包括局部非淀粉多糖纤维素、半纤膳食纤维包括局部非淀粉多
18、糖纤维素、半纤维素、木质素、果胶等、抗性淀粉、葡聚糖维素、木质素、果胶等、抗性淀粉、葡聚糖以及局部低聚糖等。以及局部低聚糖等。第二十七页，共六十二页。(1)(1)增强肠道功能、有利粪便排出增强肠道功能、有利粪便排出 Helps prevent constipation and other intestinal problems by keeping our stools moist and soft.Functions of dietary fiberDietary fiber increases faecal bulk through water binding by fiber.Fiber
19、 gives gut muscles“something to push and makes it easier to eliminate stools.第二十八页，共六十二页。(2)控制体重和减肥控制体重和减肥 May enhance weight loss,as eating a high fiber diet causes a person to feel more full.Fiber absorbs water,expands in our intestine,and slows the movement of food through the upper part of the d
20、igestive tract.第二十九页，共六十二页。(3)(3)降低血糖和血胆固醇降低血糖和血胆固醇Decrease the level of blood sugar and cholesterol May reduce the risk of heart disease by delaying or blocking the absorption of dietary cholesterol into the bloodstream.第三十页，共六十二页。(4)(4)降低结肠癌的发病风险降低结肠癌的发病风险May reduce the risk of colon cancer.While
21、there is still some controversy surrounding this issue,many researchers believe that fiber binds cancer-causing substances and speeds their elimination from the colon.第三十一页，共六十二页。三、碳水化合物的消化及吸收三、碳水化合物的消化及吸收|We have learned many forms of CHOs containing in our foods,which one is the form of energy use
22、d by our bodies?|The primary goal of CHO digestion is to break down polysaccharides and disaccharides into monosaccharides that can be converted to glucose.第三十二页，共六十二页。Digestion of carbohydrates in foods(In the mouth)CHO digestion begins in the mouth.Question:When you eat steamed bread馒馒头头,notice th
23、at you can actually taste it becoming sweeter,Why?第三十三页，共六十二页。Saliva amylase淀粉酶淀粉酶 breaks starch(淀淀粉粉 into smaller particles and eventually into the maltose麦芽糖麦芽糖.|Disaccharides are not digested in the mouth.第三十四页，共六十二页。|In the stomach,all digestion of CHOs ceases.Digestion of carbohydrates in foods
24、(In the stomach)|Because the acid in the stomach inactivates most of the salivary amylase enzyme.Would you guess the reasons?第三十五页，共六十二页。|The majority of carbohydrate digestion occurs in the small intestine.Digestion of carbohydrates in foods(In the small intestine)|Pancreatic amylase secreted by th
25、e pancreas into the small intestine.|Pancreatic amylase continues to digest any remaining starch into maltose麦芽糖麦芽糖.第三十六页，共六十二页。Additional enzymes found in the intestinal tract break down disaccharides into monosaccharides.MaltoseSucroseLactoseGlucoseGlucose&FructoseGlucose&GalactoseMaltaseSucraseLa
26、ctaseAbsorbed by mucosal cellsBlood stream麦芽糖麦芽糖蔗糖蔗糖乳糖乳糖第三十七页，共六十二页。Transform of carbohydrates in the liverFructose&galactoseGlucoseCellEnergyGlycogenBlood vesselsBlood vessels第三十八页，共六十二页。|Excess glucose can be transformed and stored as glycogen in liver and muscles.Our liver can store 70g(or 280 ca
27、lories)of glycogen.Our muscles can normally store about 120 g(or 480 cal)of glycogen.Transform of carbohydrates in the liver第三十九页，共六十二页。|Liver glycogen：maintains blood glucose levels,provide the needs of our cells,including those of our brain,spinal cord and red blood cell.|In addition,It provide en
28、ergy to the muscles during intense exercise剧烈运动剧烈运动.第四十页，共六十二页。|We do not possess enzymes that can break down fiber.|Thus,fiber passes through the small intestine undigested and enters the large intestine or colon.There is no any digested process for fiber。第四十一页，共六十二页。|Once into the large intestine,
29、bacteria break down some undigested carbohydrates,causing the production of gas and a few fatty acids产酸、产气产酸、产气.Digestion of carbohydrates in foods(In the large intestine)|The cells of the large intestine use these fatty acids for energy.|The fiber remaining in the colon adds bulk to our stools and
30、is excreted in feces.第四十二页，共六十二页。Salivary amylase breaks down starch into shorter polysaccharides and a few maltose.No digestion takes placePancreatic amylase is secreted into small intestine.Majority of starch were digested.Pancreatic amylaseSpecific enzymes；All monosaccharides are absorbed by smal
31、l intestine and enter bloodstream.Monosaccharides travel to liver in bloodstream,then to cells to provide energy;Excess glucose is stored as glycogen in liver.Bacteria break down some undigested CHO;remaining fiber is excreted in feces.Summary第四十三页，共六十二页。四四、碳水化合物的功能碳水化合物的功能Function of carbohydrates1
32、.1.提供和贮存能量提供和贮存能量provide and store energyprovide and store energyHow much？4kcal/g.|Some of our cells can also use fat and even protein for energy if necessary.However,our red blood cells can utilize only glucose and our brain&other nervous tissues primarily rely on glucose.第四十四页，共六十二页。CarbohydrateFa
33、tAmounts of carbohydrate and fat used during the different extent of exercise.LightModerate Intense67%45%13%87%55%33%Percent contribution to total energynFat breakdown is a slow process and require oxygennwe can break down glucose very quickly either with or without oxygen.第四十五页，共六十二页。Function of ca
34、rbohydrates2.2.节约蛋白质作用节约蛋白质作用(CHOs spare proteins)定义：定义：当摄入足够的碳水化合物时，可以防止体内和当摄入足够的碳水化合物时，可以防止体内和膳食中的膳食中的蛋白质转变为葡萄糖蛋白质转变为葡萄糖.糖异生糖异生(gluconeogenesis)Gluconeogenesis:The generation of glucose from the breakdown of protein into amino acids.第四十六页，共六十二页。|When our body uses proteins for energy,the amino aci
35、ds from these proteins cannot be used to make new cells,repair tissue damage,support our immune system,or perform any of their other functions.Using amino acids in this manner over a prolonged period of time can cause serious,possibly irreversible,damage to these organs.第四十七页，共六十二页。3.抗生酮作用抗生酮作用Preve
36、nt the generation of ketones)|Ketoacidosis:A condition in which excessive ketones 酮酮 体体 are present in the blood,causing the blood to become very acidic,which alters basic body functions and damages tissues.Function of carbohydratesLow carbohydrate intake can lead to ketoacidosis(酮症酸中毒酮症酸中毒第四十八页，共六十
37、二页。nThus,when carbohydrate intake is inadequate,our body seeks an alternative source of fuel for the brain and begins to break down stored fat.n acetyl-CoA is the metabolites of fatty acid oxidation.nIf inadequate carbohydrate intake continues for an extended period of time,excess acetyl-CoA can be
38、converted to ketones.nThe high acidity of the blood interferes with basic body functions,causes the loss of lean body mass,and damages many body tissues.Where do ketones come from?第四十九页，共六十二页。4.4.机体的构成成分机体的构成成分5.5.改变食物的色、香、味、型改变食物的色、香、味、型6.6.提供膳食纤维提供膳食纤维Functions of carbohydrates第五十页，共六十二页。五五、碳水化合物代
39、谢相关疾病碳水化合物代谢相关疾病n糖尿病糖尿病n低血糖症低血糖症n乳糖不耐症乳糖不耐症第五十一页，共六十二页。|Glucose molecules are too large to cross the cell membranes of our tissues independently.|To get in,glucose needs assistance from the hormone insulin.血糖的调节过程血糖的调节过程第五十二页，共六十二页。Glucose in blood enters cellsInsulin stimulates glucose transport in
40、to cellInsulin secreted by pancreas enters bloodstreamTissue cell membraneWhen blood glucose is high第五十三页，共六十二页。Glucagon secreted by pancreas enters bloodstreamGlucagon stimulates glycogen breakdownGlucose is secreted into bloodstream and transported to cellsLiver cell membraneWhen blood glucose is
41、low胰高血糖素胰高血糖素第五十四页，共六十二页。|Normally,insulin and glucagon balance each other to maintain blood glucose within a healthy range.|If this balance is altered,it can lead to health conditions such as diabetes糖尿病糖尿病 or hypoglycemia低血糖症低血糖症.第五十五页，共六十二页。血糖指数血糖指数Glycemic index，GIn定定义义：50g50g含含碳碳水水化化合合物物的的食食物物血
42、血糖糖应应答答曲曲线线下下面面积积与与同同一一个个体体摄摄入入50g 50g 碳碳水水化化合合物物的的标标准准食食物物葡萄糖或面包血糖应答曲线下面积之比。葡萄糖或面包血糖应答曲线下面积之比。n血血糖糖指指数数是是食食物物升升高高血血糖糖潜潜力力的的一一个个参参考考指指标标，反响了食物对血糖的影响程度。反响了食物对血糖的影响程度。n 高高GIGI食物能使血糖突然升高。食物能使血糖突然升高。第五十六页，共六十二页。血糖指数的应用血糖指数的应用n指导合理膳食，有效控制血糖指导合理膳食，有效控制血糖n 糖尿病人糖尿病人 n 低血糖症患者、运发动低血糖症患者、运发动n有助于控制体重有助于控制体重n改善胃
43、肠道功能改善胃肠道功能第五十七页，共六十二页。nLactose intolerance:A disorder in which the body does not produce sufficient lactase enzyme乳乳糖糖酶酶and therefore cannot digest foods that contain lactose,such as cows milk.乳糖不耐症乳糖不耐症Lactose intolerancen主要病症：胃肠不适、胀气、痉挛和腹泻等。主要病症：胃肠不适、胀气、痉挛和腹泻等。第五十八页，共六十二页。nIt is estimated that up
44、 to 70%of the worlds adult population suffer this disorder.nNot everyone experiences lactose intolerance to the same extent(small amounts,not tolerant any)Lactose intoleranceLactose intolerance should not be confused with a milk allergy.People who are allergic to milk experience an immune reaction t
45、o the proteins found in cows milk.第五十九页，共六十二页。六、膳食参考摄入量六、膳食参考摄入量Dietary reference intakesn 中国营养学会推荐我国居民的碳水化合物的膳中国营养学会推荐我国居民的碳水化合物的膳食推荐摄入量占总能量的食推荐摄入量占总能量的55%65%。食物食物GI食物食物GI食物食物GI大米饭大米饭88柚子柚子25熟香蕉熟香蕉52酸奶酸奶83鲜桃鲜桃28猕猴桃猕猴桃52牛奶牛奶27.6梨梨36芒果芒果55鲜豆腐鲜豆腐 31.9苹果苹果36菠萝菠萝66生香蕉生香蕉30柑柑43西瓜西瓜72第六十页，共六十二页。小结小结n碳水化合物的分类及功能碳水化合物的分类及功能n膳食纤维的定义及功能膳食纤维的定义及功能n乳糖不耐症乳糖不耐症第六十一页，共六十二页。内容总结第一章 营养学根底。The most abundant：glucose。抗性淀粉：指健康者小肠中不吸收的淀粉及其降解产物。四、碳水化合物的功能Function of carbohydrates。乳糖不耐症。六、膳食参考摄入量Dietary reference intakes第六十二页，共六十二页。