营养与食品卫生学 02课件

1、 第一篇 营养学PART 1 NUTRITION 1.营养：是指人体摄取、消化吸收、利用食物中营养物质和排除 废 物的生物学过程。 It is a biological process which nutrients and functional compositions in the foods are ingested, digested, absorbed, transported ,utilized and the waste are excreted. 2.营养素： (1)定义：食物中可给人体提供能量、机体构成成分和组织修复以及有生理调节功能的化学成分。 Chemical subst

2、ances obtained from food and used in the body to provide energy,structural materials,and repair of the bodys tissues; Nutrients may also reduce the risk of some diseases.(2) Classification protein lipids macronutrients carbohydrate (dietary fiber) nutrients water vitamin micronutrients macroelements

3、 minerals 核酸 nucleic acid ? microelements 3. 合理营养（Rational Diet） 通过合理的膳食和科学地烹调加工，能向机体提供足够数量的热能和各种营养素，并保证各种营养素之间的数量平衡，以满足人体的正常生理需要，并保持人体健康。 Nutrients intakes meet the requirements of the body5.膳食营养供给量(Recommended Dietary Allowance，RDA) 是对各种人群提出的保证人体营养需要的膳食中应含有的热能和营养素的适宜量。 The average daily amount of

4、a nutrient considered adequate to meet the known nutrient needs of practically all healthy people; a goal for dietary intake by individuals.4. 营养生理需要量（Nutritional Requirement） 是指能保持人体健康，达到应有发育水平和能充分有效地完成各项体力和脑力活动所需要的热能和各种营养素的必需量。 The lowest continuing intake of energy and nutrients that maintain the

5、 specified criterion of adequacy (that will maintain the specific biochemical and physiological functions of the body).Chapter 1 Basic Nutrition 第 一 章 营 养 学 基 础 含量-16%19%.更新： 动态平衡，不断更新，每天约3%，肠和骨髓最快。 Section 1 Protein ( 蛋白质 )一、蛋白质（一）人体中蛋白质：（二）功能： 1.机体构成成分 2.构成各种生理活性物质和重要的生理功能 3.提供热能 （三）The first stru

6、cture 蛋白质(protein) 氨基酸（Amino acid, AA） 非必需AA(nonessential-)：9种 半必需AA（条件必需AA）：2种 （semi-,or conditionally-）必需AA（essentional-）：9种 多肽（poly-）10 AA以上寡肽（oligo-）410 AA以下 3肽（tri-）3AA 2肽（di-）2AA 肽(peptide) 氨基酸英文氨基酸英文必需氨基酸非必需氨基酸异亮氨酸Isoleucine (Ile)丙氨酸Alanine (Ala)亮氨酸Leucine (Leu)精氨酸Arginine (Arg)赖氨酸Lysine (Lys

7、)天门冬氨酸Aspartic acid (ASP)蛋氨酸Methionine (Met)谷氨酸Asparagine (Asn)苯丙氨酸Phenylalanine (Phe)谷氨酰胺Glutamic acid (Glu)苏氨酸Threonine (Thr)甘氨酸Glycine (Gly)色氨酸Tryptophan (Trp)脯氨酸Proline (Pro)缬氨酸Valine (Val)丝氨酸Serine (Ser)组氨酸*Histidine (His)天冬酰胺Asparagine (ASN)条件必需氨基酸半胱氨酸Cysteine (Cys)酪氨酸Tyrosine (Tyr)表 1-1 人体内的氨

8、基酸*组氨酸为婴儿必需氨基酸，成人需要量可能较少。 摘自Modern Nutrition in Health and Disease,第9版,第14页,1999。(三) 氨基酸模式(AA Pattern)和限制氨基酸 (limiting AA)1. 氨基酸模式 (AA Pattern) ： 蛋白质中各种必需氨基酸的构成比例。2.限制氨基酸 （limiting amino acid）： 与人体蛋白质模式比较，食物蛋白质中含量相对较低的必需AA。 The essential amino acid found in the shortest supply relative to the amount

9、 needed for protein synthesis in the body. FourAA are mostlikelytobe limiting: Lysine，Methionine，Threonine，Tryptophan .3.参考蛋白、完全蛋白和蛋白质的互补作用参 考 蛋 白用于测定食物蛋白质质量的标准蛋白。 Reference Protein: A standard against which to measure the quality of other proteins.完 全 蛋 白必需氨基酸模式与人体蛋白质相对一致，能满足机体蛋白质合成需要的食物蛋白质。 Comple

10、te Protein: A dietary protein containing all the essential amino acids in relatively the same amounts that human being required. (including animal protein and soy protein ) Incomplete protein蛋 白 质 互 补 将两种或两种以上的食物蛋白质混合事用，使不同食物中必需氨基酸以多补少，从而提高膳食蛋白质的营养价值。 Complementary Protein: Two or more proteins whos

11、e amino acids assortments complement each other in such a way that the essential amino acids missing from one are supplied by the other.几种食物混合后蛋白质的生物价 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混合后生物价-747389Gastric Juice : 1. Acid denaturation 2. Pepsin- not highly specific but

12、 preferential attack on bonds adjacent to aromatic AA and leucine. 3.Carboxypeptidase-terminal aromatic or branch-chained; arginine or lysine; neutral- dietary Protein Panc- elastase(弹性蛋白酶)- arometic AA reatic trypsin(胰蛋白酶)- NH2- juice chymotrypsine(糜蛋白酶) - lysine, arginine dipeptide , tripeptide an

13、d free AA absorbed through the mucosal cells of small intestine peptidase through three active free AA transport systems neutral-,basic- and acidic-. Liver and other organs （二） 代谢与氮平衡(metabolism and nitrogen balance)1.代谢摄入蛋白质90克 消 化 道(30%)肌肉(50%)器官体液其它机体蛋白质氨基酸池粪便10g(1.6gN)尿75g(12gN)其它5g(0.8gN)(20%)肠

14、道内源性蛋白质70g消化、吸收蛋白质150g图1-1 蛋白质代谢及氮平衡四、食物蛋白质营养学评价 (1)真消化率（true -）(一)蛋白质含量 (content）(2)表观消化率（apparent -）:(二)蛋白质消化率(digestibility)(三)蛋白质利用率（utilization）1.Biological value, BV:生物价 The amount of protein nitrogen that is retained for growth and maintenance,expressed as a percentage of the protein nitrogen

15、 that has been digested and absorbed. To determine the actual value of an absorbed protein as it is used by the body. 2.Net Protein Utilization,NPU蛋白质净利用率 The amount of protein nitrogen that is retainedfrom a given amount of protein nitrogen eaten. To determine the amino acid composition anddigestib

16、ility of a test protein. 3.Protein Efficiency Ratio, PER: 蛋白质功效比值 A measure of protein quality assessed bydetermining how well a given protein supportsweight gain in growing rats. Used to establish the protein quality for infantformulas and baby foods.4.Amino Acid Score,AAS氨基酸评分 The lowest score is

17、the score of limiting AA which is the AAS of the protein. A method of evaluating protein quality by comparing a test proteins amino acid pattern with that of a reference protein; sometimes called chemical scoring. 表1-4 几种食物和不同人群需要的氨基酸评分模式氨基酸人群（mg/g 蛋白质）1岁以下 25岁 1012岁 成人食物(mg/g蛋白质)鸡蛋 牛奶 牛肉组氨酸26191916

18、222734异亮氨酸46282813544748亮氨酸93664419869581赖氨酸66584416707889蛋氨酸+半胱氨酸42252217573340苯丙氨酸+酪氨酸726322199310280苏氨酸4334289474446缬氨酸55352513666450色氨酸171195171412总计460339241127512504479摘自WTO Technical Report Series 724,第12页,1985年。5.Protein Digestibility corrected AAS, PDCAAS:（经消化率校正的氨基酸评分） A measure of protein

19、 quality assessed bycomparing the amino acid score of a food proteinWith the amino acid requirements of preschool-ageChildren and then correcting for the truedigestibility of the protein; Recommended by the FAO/WHO and used toestablish protein quality of foods for daily valuepercentage on food label

20、s. 表1-6 几种食物蛋白质的PDCAAS食物蛋白PDCAAS食物蛋白PDCAAS酪蛋白1.00斑豆0.63鸡蛋1.00燕麦粉0.57大豆分离蛋白0.99花生粉0.52牛肉0.92小扁豆0.52豌豆粉0.69全麦0.40菜豆0.68摘自Understanding Nutrition, 第7版，第215页，1996年。蛋白质营养不良KwashiorkorMarasmusMarasmus Kwashiorkor Infancy(less than 2 yr) older infants and young children(1-3 yr) Develops slowly;chronic PEM

21、rapid onset; acute PEM Severe weight loss some weight loss Severe muscle wasting, with fatSome muscle wasting,with retention of some body fatGrowth:60% weight-for-age growth:60%-80% weight-for-age No detectable edema edemaNo fatty liver enlarged fatty liver Anxiety焦急, apathy淡漠 apathy, misery痛苦, irri

22、tability易怒, sadness Good appetite possible loss of appetite Hair is sparse,thin and dry; Easily pulled out hair is dry and brittle; easily pull out; changes color; becomes straight Skin is dry, thin, and easily wrinkles skin develops lesion3. 高蛋白质膳食过多的危害 （problems of excess protein） Adult Bone Loss

23、(Osteoporosis骨质疏松): Calcium excretion rises as protein intake increases. Recommen-dation of calcium-to-protein is more than 20(mg) to 1(g). Cancer: population studies suggest a correlation between high intakes of animal protein and some type cancer ( cancer of colon, breast,kidneys, pancreas, and pr

24、ostate) Gain Weight: Protein-rich foods are often fat-rich foods. Others. Heart Disease: Foods rich in animal protein tend tobe rich in saturated fats and cholesterol; homocystei（高半胱氨酸）may be an independent risk factor for heart disease.六、蛋白质供给量和食物来源 （DRIs and Food source） RNI: 1) 数量 2）质量 (优质蛋白质)Ass

25、essment of protein nutrition in human body (1) Serum albumin: 35-50g/L (2) Serum transferritin: 2.2-4g/L (3) Retinol-binding protein: 26-76mg/L (4) Thyroxine-binding-albumin:280-350mg/L3. Food Source: animal and plant foods. Milk and Soy been中国居民膳食蛋白质的推荐摄入量: RNI与RDAAge (year)RNI（2000）RDA（1988）manwom

26、anmanwoman01.53.0g/kg.bw.2.04.0g/kg.bw.0.51353535352404040403454545454505050455555555506555555557606060608656565609656565651070657065RNI与RDA：续表Age (year)RNI（2000）RDA（1988）manwomanmanwoman11757570807080148580809080轻7565807018中80709080重908010090孕期早+5中+15+15晚+20+25乳 母+20+256075657565Section 2 Lipids (

27、脂类 ) 固醇类,sterols： 脂类甘油三脂,triglycerides：磷脂, phospholipids99% in body, 95% in food99% in body, 95% in food一、脂类的分类 Classification一、脂类的功能 (function) Structure：1 glycerol 3 fatty acids Function （一） triglycerides, 甘油三脂(TG)(1) triglycerides in the body: A: Storing and providing the body with energy: 1g 9.4

28、6kcal (两个特点）B: The layer of fat beneath the skin helps keep the body warm ( insulating the body) C: Protecting and propping up the organs in the body D: Helping the body use its two other energy nutrients carbohydrate and protein ( sparing protein )E: The very important composition of the body F: In

29、cretion: leptin, TNF-, IL-6, IL-8, adiponectin, resistin, estrogen, Insulin-like growth factor (IGF), angiotensinogen (血 管紧张素), IGF binding protein 3, plasminogen activator inhibitor (PAI, 纤维蛋白溶酶原激活因子抑制物)(2). Triglycerides in the foods: A: Providing body with energy and essential fatty acid. B: Impr

30、oving the color, flavor, taste and shape of foods. C: Because dietary fat causes the stomach to empty more slowly than either carbohydrate or protein, it imparts satiety and satisfaction.D: To supply body with fat-soluble vitamins and aid intestinal absorption of them. (3). risk of high-fat diet Hea

31、rt disease: Food saturated fat (especially 12, 14, 16 carbons) raises blood cholesterol dramatically, which causes heart attack or stroke. Obesity 肥胖: High-fat diet tend to store body fat efficiently. (3) Cancer: Prostate cancer is a strong association with fat; Breast cancer is a little or no assoc

32、iation with diet fat. (4) Risk from trans-fatty acids: They raise LDL and lower HDL. (二) fatty acids , 脂肪酸 (FA) chain length: long-chain (1014 carbons or more) medium-chain (6 or 8 -) short-chain ( 24 or 26) Saturation（饱和度）: saturated FA (SFA) monounsaturated FA (MUFA) polyunsaturated FA (PUFA) posi

33、tion of double bond: “n” or “” “n-3”: the initial double bond situated between the third and 4th carbon atoms from the methyl end. “n-6”: the initial double bond is between the 6 and 7 isomeric forms 异构体: cis 顺式 ； trans 反式(1) Classification(2). Essential fatty acid, 必需脂肪酸 (EFA) Definition:Classifica

34、tion: (1) linoleic acid (亚油酸). C 18:2, n-6 (2)- linolenic acid（ 亚麻酸）. C 18:3, n-3 Fatty acids needed by the body , but not made by it to meet physiological needs.Synthesize of MUFA in body linoleic acid (C18:2,n-6) -linolenic acid (C18:3,n-3) 6去饱和酶 -linolenic acid (C18:3,n-6) 十八碳四烯酸 (C18:4,n-3) 碳链延长

35、酶 bi-homotype -linolenic 二十碳四烯酸 (C20:4,n-3) acid (C18:3,n-6) 5去饱和酶 arachidic acid (AA) timnodonic acid (EPA) (C20:4,n-6) (C20:5,n-3) 碳链延长酶 二十二碳四烯酸 (C22:4,n-6) clupanodonic acid (C22:5,n-3) 4去饱和酶 二十二碳五烯酸 (C22:5,n-6) docosahexenoic acid (DHA) (C22:5,n-3)Function of EFATo maintain the structural parts

36、of cell membranes. (it is a part of phospholipids) Used to synthesize many hormone like substances- eicosanoids（二十烷） : prostaglandins (PG,前列腺 素)，Thromboxane(TXA,凝血恶烷)，leukotrienes (LT, 白三烯 ),hydroxy fatty acids, and lipoxins(脂素). (3) Lower blood cholesterol and risk of heart attack or stroke, especi

37、ally EPA (eicosapentaenoic acid) and DHA (docosahaxaenoic acid). They modulate cardiovascular, pulmonary, immune, reproductive, and secretory functions in many cells.Deficiency of EFAAffect development, production, liver, kidney, nerve, vision, and skin. (三) 磷脂 (phospholipid)1. Structure： It consist

38、 of a glycerol backbone with one or two attached fatty acids, plus a different structure that includes a phosphate group attached to the other hydroxyl group(s).The most important member is lecithins（卵磷脂）. 2. Function (1) Important constituents of cell membranes. They thus allow fat-soluble substanc

39、es, including vitamins and hormones, to pass easily in or out of cells. (3) As emulsifiers （乳化剂）in the body or food manufacturers.(4) To supply body with 9 kcalories per gram. (5) Health function: different points. (四) 固醇 (Sterols) 1. Structure: A same multiple ring with different side groups attach

40、ed. Cholesterol is the most important. 2. Function: Essential to the structure and function of cells, especially the cell membrane (about 90% of total body cholesterol ). Cholesterol is the original material for synthesis of many vitally important body compounds such as bile, sex hormones, adrenal h

41、ormone, and vitamin D.3. Harmful effects: It forms deposits (沉积物) in the artery walls which lead to atherosclerosis (动脉粥样硬化)- a disease that causes heart attacks and strokes. 二、脂类代谢（metabolism） mouth salivary gland（唾液腺）-lipase（脂肪酶）: It plays a small role in digestion in adults, but efficiently diges

42、ts the short- and medium-chain fatty acids of milk in infants. Stomach Stomachs churning 搅拌 action mixes fat with water and acid . A gastric lipase hydrolyzes a very small amount of fat. Small intestine emulsification of fat by bile Pancreatic lipase Intestinal lipase bile trapped by dietary fibers

43、and carried out of the body with the feces Reabsorbed into the blood liver Gallbladder(胆囊) Monoglyceride, fatty acids and glycerol Long-chain fatty acids Monoglycerides Glycerol, short- and medium-chain Fatty acids absorbed directly into blood Merge （结合）into micelles (微胶粒) Merge （结合）into micelles (微

44、胶粒) Easily diffuse (扩散) into the intestinal cells and reassembled (重新合成) into new triglycerides. With cholesterol and phospholipids, Chylomicrons within the intestinal cells Absorbed into lymph,then into blood Cells all over the body remove lipids from the chylomicrons（乳糜微粒） as they pass by, and mak

45、e them smaller and smaller. protein Liver cells collect the chylomicron remnants（残体）, and pack them with lipids , cholesterol and proteins as VLDL which will travel through the body in the blood. HDL made in the liver carry cholesterols and phospholipids from the cells back to the liver. They lose t

46、riglycerides and gather cholesterol fromOther lipoproteins circulating through the bloodstreamAnd become LDLMetabolism of cholesterol三、 Food source and RDA 脂类的食物来源及供给量 1. Food source: 1). Animal fat: plenty of SFA 2). Vegetable oil: plenty of MUFA Linoleic Acid (n-6) leafy vegetables, seeds, nuts, g

47、rains, vegetable oil(corn,safflower 红花, soybean, cottonseed, sesame芝麻, sunflower) Arachidonic Acid (n-6) meats, can be synthesized from linoleic acid linolenic acid（n-3） fats and oil ( soybean, walnut胡桃, wheat germ) EPA and DHA (n-3) Human milk, shellfish and fish (mackerel 鲐鱼, tuna 金枪鱼, salmon大麻哈鱼,

48、 sturgeon鲟鱼, herring鲱鱼, trout鳟鱼, sardines沙丁鱼), can be made from linolenic acid. 2. DRIs: basic principle percentage of total dietary energy ：20%-30% SFA / total dietary energy 10%n-6 / total dietary energy 3%, n-6n-341 Cholesterol 300mg/d3. Substitute of fat 蔗糖聚酯 sucrose polyester, Olestra燕麦素 Ostrim

49、 AIs of dietary fat (percentage of total dietary energy )注1：SFA为饱和脂肪酸；MUFA为单不饱和脂肪酸；PUFA为多不饱和脂肪酸注2：n-6/n-3表示n-6系列不饱和脂肪酸与n-3系列不饱和脂肪酸的比例AgeyearFat%SFA%MUFA%PUFA%n-6/n-3Cholesterolmg045 50410.5354041230354617253046114253010810461182030101010461 30060203068108104160(13.5 W)+487(10.5 W)+596注:W为体重(kg)。摘自Te

50、chnical Report Series724,Geneva,WHO,1985。表1-12 人体24小时静息代谢参值(Kcal)年龄(y)40 50 57 64 70 77 84 91 100体重（kg） 男性101813511526164817711876199821212243240118301291144415511658175018571964207122093060134314591540162116911772185319352039 60102711621256135114231526162117161837女性101812341356144115271600168517711

51、85619661830108412311334143715251628173118331966306011771264132513861438149915601621169960101611211195126813311404147815521646摘自Nutrition Science and Application,第二版，第190页,1997。4. The factors affecting BMR (1) Body surface area: (or lean mass fatty tissue)(2) Gender: male female (3) Age: 2% of declin

52、e per 10 years after age 30 5% of decline per 10 years after age 60 (4) Nutrition state: Low energy intake decreases BMR about 10%-20% (5) Physiological status: Pregnancy increases BMR (6) Body temperature: Fever increases BMR (7) High or low air temperature, hormone system activity, nerve and eatin

53、g too much increase BMR (Adaptive Thermogenesis , 适应性生热作用) (8) Caffeine and tobacco increase BMR (二) Physical Activity The energy needed during physical activity depends on body lean mass, intensity (强度) and time of activity. The energy is about 15%-30% of total energy use in sedentary(久坐的) people.

54、(三) Specific dynamic action (or Thermic Effect of Food, TEF)食物特殊动力作用或食物热效应 1. Definition The amount of extra energy used by body during digestion, absorption, metabolism, and storage of energy-yielding nutrients. 2. Energy expenditure 5%-6% of total calorie produced by carbohydrates carbohydrateslip

55、ids 4%-5% of that protein 30% of that mixed food 10% 0f total energy consumed（消耗） 3. The mechanism Energy storage: ATP and fat (2) Sympathetic nervous system activity (交感神经系统活动) 4. Affecting factors (1) protein-rich food is much higher then others(2) large meals show higher values than normal meals(

56、3) TEF decreases with advancing age. (4) Meal frequency. (一) calculation 三、热能需要量的确定 Estimating energy requirements 1. calculating the total energy expenditure basal metabolism physical activities specific dynamic action 2. Nutritional survey (or Dietary survey) (二) measuring energy use by body（测量法)1. Direct calorimetry A method of determining a bodys energy use by measuring heat that emanates（散发） from the body, usually using an Insulated chamber（绝热仓）2. Indirect calorimetry A method of measuring a bodys energy use by measuring its oxygen uptake (and often carbon dioxide