第一章 营养学基础

1、第一章 营养学基础 第一节 蛋白质 一目的和要求本节是营养学第一章中重点内容；要做到全部掌握。二重点和难点重点：蛋白质生理功能，必需氨基酸。蛋白质营养学评价，食物来源和供给量。难点：食物蛋白质营养学评价有关指标及原理。三、教学安排教学时数：2学时四、教学方法重点讲授，复习、提问、讨论相结合。应用多媒体课件。五、授课内容第一节 蛋白质 概念，生理功能，氨基酸和必须氨基酸，蛋白质在体内的消化、吸收和代谢 食物蛋白质营养评价，蛋白质的营养不良，蛋白质来源及供給量一. 蛋白质的生理功能1.是人体组织的构成成分2.是构成体内各种重要生理活性物质 增加免疫功能 维护神经系统的正常功能 遗传信息的控制 维持

2、毛细血管的正常渗透压 运输功能 维持血液的酸碱平衡 参与凝血过程3.供给热能蛋白质的组成及一般性质基本组成元素：碳、氢、氧、氮一般性质：高分子物质，不能透过半透膜；两性分子，具有酸性和碱性，可成为缓冲体系与水形成乳胶悬浮液可发生变性和凝固二. 氨基酸和必需氨基酸1.氨基酸和肽2.必需氨基酸(essential amino acid ,EAA)概念：种类 异亮氨酸、亮氨酸、 赖氨酸 蛋氨酸、 苯丙氨酸、 苏氨酸 色氨酸、 缬氨酸、 组氨酸氨基酸膜式和限制性氨基酸氨基酸模式与限制氨基酸氨基酸模式（Amino Acid Pattern）限制氨基酸（limiting amino acid）优质蛋白质及

3、参考蛋白质 优质蛋白质 参考蛋白质(reference protein) ：鸡蛋蛋白，人乳蛋白蛋白质的互补作用 (supplementary action) 蛋白质是由多种氨基酸构成的。由于各种食物中的氨基 酸组成不尽相同，在某一种食物中缺乏的氨基酸可能在另一种食物中含量丰富。当食物蛋白质中某一种或某几种氨基酸缺乏或不足时，则使合成机体组织蛋白质受到限制。如果将各种食物按合适的比例混合食用，其蛋白质可起到相互补充的作用，即各种食物蛋白质中的氨基酸可以取长补短，最后成为一种更适合人体吸收利用的较为完美的混合膳食，从而起到提高蛋白质利用率的作用，这就称为蛋白质的互补作用。三、蛋白质在体内的消化、吸

4、收和代谢 摄入的蛋白质在体内经酶的水解最终成为各种氨基酸，但实际上人体的血浆中存在两种氨基酸的来源：即从体外摄入蛋白质和体内蛋白质分解后被机体吸收再利用的氨基酸。 氮平衡(nitrogen balance)摄入氮与排出氮的关系。表达式 : NB=I-（U+F+S）I=摄入氮 U=尿氮 F=粪氮 S=皮肤损失氮 零平衡 摄入氮=排出氮 氮平衡 正平衡 摄入氮排出氮 负平衡 摄入氮 fatty tissue)(2) Gender male female(3) Age 2% of decline per 10 years after age 30 5% of decline per 10 years

5、 after age 60(4) Nutrition stateLow energy intake decreases BMR about 10%-20%(5) Pregnancy increases BMR(6) Body temperature Fever increases BMR(7) High or low air temperature, hormone system activity, nerve and eating too much increase BMR (Adaptive therogenesis，适应性生热作用)(8) Caffeine and tobacco inc

6、rease BMR(二） Physical ActivityThe 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.（三）Specific dynamic action (or Thermic Effect of Food,TEF)食物特殊动力作用或食物热效应1Definition：The am

7、ount of extra energy used by body during digestion, absorption, metabolism, and storage of energy-yielding nutrients.2Energy expenditurecarbohydrates 5%-6% of total calorie produced by carbohydrates lipids 4%-5% of thatprotein 30% of thatmixed food 10% 0f total energy consumed（消耗）3The mechanism (1)

8、Energy storage: ATP and fat(2) Sympathetic nervous system activity (交感神经系统活动)4Affecting factors(1) protein-rich food is much higher then others(2) large meals show higher values than normal meals(3) TEF decreases with advancing age.(4) Meal frequency.三、热能需要量的确定Estimating energy rquirements（一）calcula

9、tion1calculating the total energy expenditurebasal metabolism physical activities specific dynamic action2 Nutritional survey (or Dietary survey):营养或膳食调查(二）measuring energy use by body（测量法）1 Direct calorimetry2 Indirect calorimetry四、热能推荐摄入量Energy Recommended Nutrition Intake, RNI五、Health and energy

10、intake（一）the risk of excessive energy（二）限食Energy restrictionIt is beneficial to prevention of many diseases especially for old people, and prolonging life. 第五节 矿物质 SECTION 5 MIMERALS一目的和要求1掌握钙、铁、碘、锌、硒等元素的生理功能，吸收与代谢，缺乏病，食物来源与供给量。2熟悉人体无机盐和微量元素的构成。3了解磷、铜、锰、钴、钼、铬、镍等有关内容。 二重点和难点1重点为钙、铁、碘、锌、硒的生理功能，缺乏病，代谢及

11、食物来源与供给等。2元素的代谢及有关机理。 三、教学安排教学时数：4学时四、教学方法重点讲授，复习、提问、讨论相结合。应用多媒体课件。五、授课内容 Introduction1.Elements in human body1.1 Total elements In human body is 0ver 80.1.2 Essential elements in human body over 20, of them about 20 are mineral elements(1) Macroelements: Ca, P, Na, K, Mg, S, CL.(2) Microelements: F

12、e, Zn, Se, I, Cu, Co, Cr, F, Mn, Mo, Si, Ni, B, V.2. Function1.1 Composition of human body1.2 Maintain the pH and osmotic pressure (渗透压) of body liquids. 1.3 Regulating the exciting of nerve and muscle 1.4 Components of prosthetic group(辅基), hormone, vitamin, protein, nucleic acid, and activator（激活剂

13、） of enzyme.1.5 The othersCalcium1Calcium in human body Ca in the body: 850-1200g 1.5%-2.0% of body weightBone , teeth, 99%: Combined form, 0.5%: Ion, 0.5%：Hydroxyapatite combined with Miscible Ca Pool（羟磷灰石） protein and （混溶钙池）amorphous Ca citric acid In blood, extra- （未定形钙） cellular fluid, soft tiss

14、ue, and exchangeable2. Function2.1 Principal component of skeletal tissue osteoblasts(成) Bone Ca (miscible Ca pool) Osteoclasts(破) Renewal: Children 1-2 year Adult 10-12 y (2%-4% per year, 700mg/d)After 40y, Ca in the bone decreased by 1% per year: earlier infemales than in males; Most rapidly durin

15、g first 3years After menopause;Taller people less rapidly.2.2 Regulating neuromuscular(神经肌肉) excitability, maintaining transmission of nerve impulses(神经冲动) and heart beats.2.3 Influencing enzymereaction: ATPase(三磷酸腺苷酶), proteinase(蛋白酶), Lipase(脂肪酶), succinodehydrogenase(琥珀酸脱氢酶)。2.4 Others: hormone s

16、ecretion, blood coagulation(凝结), acid-base balance, normal colloid(胶体).3Absorption and Metabolism3.1 Mechanism of absorption: in the small intestine(1) Transcellular(跨细胞): saturable(可饱和的) (active) transfer that involves a calcium-biding protein, calbindin(钙结合蛋白).(2) Paracellular(同细胞水平)3.2 Affecting

17、factors(1) Age children: 75% 0f ingested Ca; 40% of food Ca adults: 30%-60%; 20% 70y 1/3 of adults; female(3) Physiological situation: pregnancy and breast-feed others(4) Body Ca conc.(5) Dietary factorsincreasing Ca absorption: Vit. D, lactose, amino acids: lysine argininedecreasing : phytate(植酸盐),

18、 oxalate(草酸盐), fibre, fatty acid, alcohol; thyroid hormone(甲状腺素), cortisol(皮质醇), and antibiotics: penicillin, neomycin,chloramphenical(氯霉素)3.3 Excretion3.3.1 Fecal Ca 194 73 mg/d in the American men from unabsorbed Ca and endogenous Ca(内源性钙)3.3.2 Urine Ca：diets containing 600-800 mg/d ranges between

19、 80-250mg in urine.3.3.3 Sweat Ca: 20-30mg/d; 1g/d at high temp.3.3.4 Milk Ca: 150-300mg/d3.4 Biologic control system for homeostasis(体内平衡) of CaVit.D and parathyin(甲状旁腺素): renal reabsorptionCalcitonin(降血钙素): inhibiting bone loss and increasing urine CaCalmodulin(钙调节素): regulating the Ca in the cell

20、.4 DRIs of Ca4.1 Estimating DRIs（膳食参考摄入量）(1) Infants: mean intake of breast milk(母乳) (2) Others: Ca balance test(平衡试验)(3) Direct measure4.2 DRIs (mg/d )5 Dietary sourcemilk, small shrimps(小虾), kelp(海带), legumes(豆类): soy bean、 black soya bean(黑豆), red bean(红豆), sesame paste(芝麻酱), and many Ca suppleme

21、nts(钙补充剂).Iron (铁)1 Body iron Body iron (4-5g) Functional Fe (75%): Storage Fe (25%):2 Physiologic functions2.1 Important role in oxygen and electron transport2.2 Others: catalyzing -carotene Vit.A; promoting produce of antibody;lipids transport in blood;detoxifying drugs in liver-3 Absorption and M

22、etabolism3.1 Absorption of nonheme iron(非血红素铁)3.1.1 factors of decreasing absorption(1) rapid transit time(2) achylia(胃液缺乏), malabsorption syndromes (3) precipitation(沉淀) by alkalinization(碱化), phosphates(4) phytates(植酸), oxalate(草酸) and antacids(抗酸剂)(5) iron dosage3.12 factors of increasing absorpt

23、ion(1) iron dosage(2) vit.C, B2; amino acids: cysteine(半胱氨酸)(3) MFP factor (meat fish poultry factor，肉鱼禽因子)(4) Ca, Fe help each other to diminish the inhibitors3.2 absorption of heme iron(血红素铁)The absorption is not influenced by inhibitors which decrease the absorption of nonheme iron.3.3 absorption

24、 rate of iron in the foodsrice 1% corn 3% black bean 3% lettuce 4% flour 5% soybean 6% fish 11% hemoglobin 15% mustle, liver 22%4 iron-deficiency anemia4.1 iron-deficiency anemiaChina: 40% 0f children under 3 yWorld: 4y, 0.6%-7.7% 5-8y, 5.5%young healthy women 35%-58%4.2 ReasonPoor dietsPoor absorpt

25、ionBlood loss: menstruation(月经), hemorrhage(出血), 0.5 mg Fe per ml blood.Pregnancy4.3 The process assessment of iron-deficiency anemia (IDA)first stage iron decrease(ID): stored iron exhaustion, serum ferritin.Second stage Iron-deficiency in erythrocytosis(红细胞生成缺铁期): serum Fe and ferritin, iron-bidin

26、g capacity(saturation of transferrin,运铁蛋白饱和度), cons. 0f free erythrocyte protoporphyrin (FEP)(游离原扑啉) Third stage IDA: hemoglobin and hematocrite values decline.4.4 Deficiency symptomsImmune system: Reduced resistance to infection( lowered immunity) Nervous/Muscule systems: Reduced work productivity,

27、 tolerance to work; Reduced physical fitness(健康)Skin:itching(痒); pale nailbed(指甲床), eye membranes, and palm creases(掌心起皱); concave nails(凹面指甲); impaired wound healing(愈合).General:Reduced resistance to cold, inability to regulate body temperature, pica (clay eating, ice eating) （异食癖）5 DRIs men: 15mg/

28、d women: 20mg/dpregnancy 25-35mg/d wet nurse 25mg/d 6 Food source Iodine （碘）1 Iodine in the body (20-50mg) tetraiodothyronine(T4), 16.2%(甲状腺素) thyroid triiodothyronine(T3),7.6%(三碘甲状腺原氨酸)iodine(8mg) diiodothyronine(DIT),33.4%(二碘酪氨酸) monoiodothyronine(MIT),32.7%(一碘酪氨酸) othersIn blood: protein-binding

29、iodine, 30-60g/L2. function: thyroxin(T4)(甲状腺素)（1） regulating oxidation reactions in cells and energy metabolism.（2） Regulating protein synthesis by linking to the processes of genetic control in the nucleus.（3） Promoting the synthesis of cholesterol, intestinal absorption of carbohydrate and conver

30、sion of carotene to VitA.（4） Regulating the metabolism of water and electrolyte.（5） Influencing the growth and development,and metal development.(15% mental retardation in ID area in china )3. absorption and metabolism 4. iodine deficiency IDD Adults: goiter Teenagers: influencing growth,development

31、 of body and mental. Infants: dementiaSupplement of iodide: iodized salt KI: 1:100000 KIO3:1:20000500005.effects of excess iodine iodine goiter6.DRIs adults: 150ug/d pregnancy 175ug/d wet nurse 200ug/d UL 850ug/d7.dietary source: sea foodskelp 24mg/100g sea slug(海带) 0.6mg/100g mussel(淡菜) 1mg/100g la

32、ver(紫菜)1.8mg/100g Zinc1. zinc in the body(2-3g) 肝、脾、肌肉、骨骼、眼中较多 blood(900ug/100ml)found in all human prostate(前列腺)tissues (10-200ug/g) prostatic secretionsspermatozoa2. functions and zinc deficiency(1) essential constituent of over 100 enzymes,in each of the 6 major enzyme categories(2) Influencing g

33、rowth, development and sexual system. involving the synthesis of DNA,RNA protein(anorexia 厌食，failure to grow, testicular atrophy 睾丸萎缩,skin lesions )(3) Having normal appetite.(4) Promoting metabolism of Vit A.(5) Maintaining the reproduction of immune cells.(6) Involving in neoplastic processes.3. m

34、etabolism(shorten)4. DRIs and dietary source(1) DRIs: (2) dietary source: seafoods and meats.Selenium1.Se in the body In various amounts in all tissues of the body except fatBody size the highest concentration is in liver, heart,(14-20mg) kidney and spleenblood Se is 0.22ug/ml2.function and Se defic

35、iency(1) a constituent of glutathione peroxidase(GSH-Px), antioxidant and anticancer.(2) Detoxification: heavy metals,AFB1.(3) Anticarcinogenic effect : skin,liver,colon,breast,etal.(4) Enhancement of humoral, cell-mediated and nonspecific immunity.(5)Maintain heart and cardiovascular structure and function (6)Keeping normal growth (7)reducing free radical reaction