1、第一章 营养学根底,碳水化合物Carbohydrates,第一页，共六十二页。,Main contents,Definition of carbohydratesClassification of carbohydratesDigestion&absorption of CHOFunctions of carbohydratesDisorders related to CHO metabolismDietary reference intakes of CHOs,第二页，共六十二页。,Carbohydrates are one of the three macronutrient types
2、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、氢、氧构成。,一、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 foods such as fruits,vegetables,and grain.,Why?,第四页
3、，共六十二页。,Plants make carbohydrates through the process of photosynthesis,Energy from sun,Carbon dioxide from air,Glucose stored in plant,Water,Water+Carbon dioxide,Glucose,光合作用,第五页，共六十二页。,二、碳水化合物的分类Classification of carbohydrates,双糖,多糖,第六页，共六十二页。,The three most common monosaccharides.ALL of them cont
4、ain identical atoms,Structure of monosaccharides,第七页，共六十二页。,Monosaccharides-Glucose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
5、our bodies,glucose is the preferred source of energy for the brain.,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，葡萄糖优先为大脑提供能量。,第八页，共六十二页。,Monosaccharides-Fructose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。,Monosac
6、charides-Galactose半乳糖,Galactose 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,Disaccharide:A carbohydrate
7、 compound consisting of two sugar molecules joined together.,The three most common disaccharides found in foods are lactose乳糖,maltose 麦芽糖,and sucrose 蔗糖.,第十二页，共六十二页。,Disaccharides Lactose乳糖,Lactose:Consist of one glucose molecule and one galactose(半乳糖 molecule.,第十三页，共六十二页。,DisaccharidesMaltose 麦芽糖,M
8、altose: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,Sucrose is composed of one glucose molecule and one fructose果糖 molecule.,Sucrose provides much of the
9、sweet taste found in honey,fruits,and vegetables.,How about the Sucrose and fructose?,Sweeter than lactose or maltose,why?,第十五页，共六十二页。,哪种双糖最甜-麦芽糖，蔗糖，乳糖？,麦芽糖-2个葡萄糖蔗糖-1个葡萄糖+1个果糖乳糖-1个葡萄糖+1个半乳糖,蔗糖,第十六页，共六十二页。,Oligosaccharide寡糖,Oligosaccharide are composed of 3 to 10 monosaccharides.The most common oligo
10、saccharides are raffinose 棉籽糖and stachyose水苏糖.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,Polysaccharides include starch淀粉,glycogen糖原 and most fibers纤维.,第十八页，共六十二页。,Polysaccharides,Starch,Glycogen,Fiber,淀粉,糖原,
11、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,Excellent food sources of starch include?,grains(wheat,rice,corn,oats,and barley),legumes(peas,beans,and lentils),and tubers(potatoes and yams).,第二十页，共六十二页。,Our
12、bodies easily digest most starches，we call them digestible starch(可吸收淀粉.根据其结构可分为直链淀粉amylose和支链淀粉amylopectin，前者易使食物老化，后者易使食物糊化gelatinization。,第二十一页，共六十二页。,However,some starch in plants is not digestible and is called resistant starch抗性淀粉.抗性淀粉：指健康者小肠中不吸收的淀粉及其降解产物。,第二十二页，共六十二页。,When our intestinal bact
13、eria try to digest resistant starch,a fatty acid called butyrate is produced.Consuming resistant starch may be beneficial because butyrate is suggested to reduce the risk of cancer.,豆科食物Legumes含有的抗性淀粉比谷类、蔬菜和水果多。,Bean sprout,Green soybean,第二十三页，共六十二页。,Glycogen:A polysaccharide stored in animals,inclu
14、ding humans.Very little glycogen exists in food.Thus,glycogen is not a dietary source of carbohydrate.,Polysaccharide-Glycogen糖原,第二十四页，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 en
15、ergy.,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 fibers不溶性纤维:cellulose纤维素,hemicellulose半纤维素 and xylogen木质素.Soluble fibers可溶性纤维:果胶pectin)，树胶和粘胶.,Polysaccharide-Fiber,第二十六页，共六十二页。,膳食纤维dietary fiber：是指植物性食物或原料中糖苷键大于3个，不能被人体
16、小肠消化和吸收，但对人体健康有意义的碳水化合物。膳食纤维包括局部非淀粉多糖纤维素、半纤维素、木质素、果胶等、抗性淀粉、葡聚糖以及局部低聚糖等。,第二十七页，共六十二页。,(1)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 fiber,Dietary fiber increases faecal bulk through water binding by fiber.Fiber 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 May enhance weight loss,as eating a high fiber diet causes a person to feel more full.,Fiber absorbs w
