浙江工商大学食品营养学教案(第一章)课件.ppt

1、Chapter1Food Choices and Human HealthnFood:medically,any substance that the body can take in and assimilate that will enable it to stay alive and to grow;the carrier of nourishment;socially,a more limited number of such substances defined as acceptable by each culture.nNutrition the study of the nut

2、rients in foods and in the body;sometimes also the study of human behaviors related to food.nDiet the foods(including beverages)a person usually eats and drinks.nNutrients components of food that are indispensable to the bodys functioning.They provide energy,serve as building material,help maintain

3、or repair body parts,and support growth.The nutrients include water,carbohydrate,fat,protein,vitamins,and minerals.nMalnutrition any condition caused by excess or deficient food energy or nutrient intake or by an imbalance of nutrients.Nutrient or energy deficiencies are classed as forms of undernut

4、rition;nutrient or energy excesses are classed as forms of overnutrition.A Lifetime of NourishmentnYour body renews its structures continuously,and each day it builds a little muscle,bone,skin,and blood,replacing old tissues with new.It may also add a little fat,if you consume excess food energy(cal

5、ories),or subtract a little,should you consume less than you require.nIn this way some of the food you eat today becomes part of you tomorrow.A Lifetime of Nourishmentn The best food for you,then,is the kind that supports the growth and maintenance of strong muscles,sound bones,healthy skin,and suff

6、icient blood to cleanse and nourish all parts of your body.n This means you need food that provides not only energy but also sufficient nutrients,that is,enough water,carbohydrates,fat,protein,vitamins,and minerals.If the foods you eat provide too little or too much of any nutrient today,your health

7、 may suffer just a little.It the foods you eat provide too little or too much of one or more nutrients every day for years,then,by the time you are old,you may well suffer severe disease effects.A Lifetime of Nourishment The nutrients in food support growth,maintenance,and repair of the body.Deficie

8、ncies,excesses,and imbalances of nutrients bring on the diseases of malnutrition.nHow Powerful Is a Nutritious Diet in Preventing Diseases?n Your choice of diet profoundly influences your long-term health prospects.Only two common lifestyle habits are more influential:smoking and other tobacco use,a

9、nd excessive drinking of alcohol.Many older people suffer from debilitating conditions that could have been largely prevented had they known the nutrition principles that we know today and applied those principles throughout their lives.nmalnutrition just described,but also other diseases,especially

10、 the chronic diseasesnheart disease,diabetes,some kinds of cancer,dental disease,adult bone loss,and others.We should hasten to say that although diet can powerfully influence these diseases,they cannot be prevented by a good diet alone;they are to some extent determined by a persons genetic constit

11、ution,activities,and lifestyle?Within the range set by your inheritance,however,the likelihood that you will develop these diseases is strongly influenced by your food choices.Nutrition profoundly affects health.Genetics and IndividualitynChoice of diet influences long-term health,within the range s

12、et by genetic inheritance.Nutrition has no influence on some diseases but is closely linked to others.nChronic diseases.chronic diseases long-duration degenerative diseases characterized by deterioration of the body organs;examples include heart disease,cancer,and diabetes.nAnemia is a blood conditi

13、on in whirl red blood cells are inadequate or impaired,and so cannot meet the oxygen demands of the body.More about the anemia of sickle-cell disease in Chapter 6;iron-deficiency anemia is described in Chapter 8nWith higher concentration of HbS(eg.SCD)and low oxygen levels,HbS forms polymers inside

14、red blood cells.nHbS polymers cause red blood cells to form“sickle”shapes.nSickle shaped red blood cells have decreased ability to travel through blood vessels which,in turn,may clog blood vessels in organs and lead to loss of tissue function.Sickle CellNormal CellWhy Bother to Be Active?Persons dai

15、ly food choice can powerfully influence the long-term health,but the combination of nutrition with physical activity is more powerful still.People who are active may receive these benefits:nReduced risk of cardiovascular diseases.n Reduced risk of some types of cancer(especially of the colon or brea

16、st).nImproved mental outlook and lessened likelihood of depression.nImproved mental functioning.n Feeling of vigor.n Feeling of belonging-the fun and companionship of sports.n Strong self-image and self-confidence.n Reduced body fatness and increased lean tissue.n Greater bone density and,thus,lesse

17、ned risk or reduced severity of bone disease later in life.n Sound,beneficial sleep.n A more youthful appearance,healthy skin,and improved muscle tone.n n Faster wound healing.n Improvement or elimination of menstrual cramping.n Improved resistance to colds and infection.Lifestyle Choices nOther lif

18、estyle choices beside peoples choice of what foods to eat,also affect their health.Tobacco and alcohol use and other substance abuse can all be destructive of health.nPersonal life choices,such as use of tobacco or alcohol or staying physically active,also affect health for the better or worse.The H

19、uman Body and Its FoodAs your body lives each day,it moves and works,and to moves or works,it must use energy.The energy that fuels the bodys work comes indirectly form the sun by way of plants.sun-plant-animal-youSolar energy fruits grains vegetables The Nutrients in FoodsFigure 1-2 Materials of Fo

20、od and the Human BodyFoods and the human body are made of the same materials.nFood supplies energy and nutrients.The most vital nutrient is water.The energy yielding nutrients are carbohydrates,fats(lipids),and protein.The helper nutrients are vitamins and minerals.Food energy is measured in calorie

21、s;food and nutrient quantities are often measured in grams.nCalorie values of energy nutrientsnCarbohydrate 4 cal/g 17 kJ/gnFat (lipid)9 cal/g 38 kJ/gnProtein 4 cal/g 17 kJ/gncalories units of energy.Strictly speaking,the unit used to measure the energy in foods is a kilocalorie(kcalorie,or Calorie)

22、:it is the amount of heat energy necessary to raise the temperature of a kilogram(a liter)of water 1 degree Celsius.nEnergy-yielding nutrients:The nutrients the body can use for energy.They may also supply building blocks for body structures.Carbohydrate Fat ProteinnEssential nutrients:The nutrients

23、 the body cannot make for itself(or cannot make fast enough)from other raw material;nutrients that must be obtained from food to prevent deficiencies.Can I Forgo Food and Live Just on supplements?nsupplements pills,liquids,or powders that contain purified nutrients or other ingredients(see Chapter 7

24、).nelemental diets diets composed of purified ingredients of known chemical composition;intended to supply all essential nutrients to people who can not eat foods.What Are the Nonnutrients and Phytochemicals That I Hear about in the News?n Foods contain compounds other than nutrients,the phytochemic

25、als,that give them their tastes,aromas,colors,and other characteristics.Some phytochemicals are believed to play roles in disease prevention.The science of nutritionIf the Scientists Dont Know,How Can I!nEveryone stampedes for oat bran,red wine,or fish oil based on todays news that these products ar

26、e good for health.Then tomorrows news reports,It isnt true after all,and everyone drops oat bran,red wine,or fish oil and takes up the next craze.Meanwhile,bewildered consumers complain in frustration,Those scientists dont know anything.nIn truth,though,it is a scientists business not to know.Scient

27、ists obtain facts by systematically asking questions-thats their job.Then they conduct experiments designed to test for various possible answers(see Figure 1-3 and Table 1-4 on the next page).nWhen they have ruled out some possibilities and found evidence for others,they submit their findings,not to

28、 the news media,but to boards of reviewers composed of other scientists who try to pick the findings apart.If the reviewers consider the conclusions to be well supported by the evidence,they endorse the work for publication,not in the news media,but in scientific journals where still other scientist

29、s can read it.Figure 1-3 Research DesignScientific Challenge nOnce a new finding is published,it is still only preliminary.One experiment does not prove or disprove anything.The next step is for other scientists to attempt to duplicate and support the work of the first researchers or to challenge th

30、e finding by designing experiments to refute it.Can I Trust the Media to Deliver Nutrition News?nThe news media are hungry for new findings,and reporters often latch onto ideas from the scientific laboratories before they have been fully tested.Or a reporter who lacks a strong understanding of scien

31、ce may misunderstand complex scientific principles)To tell the truth,sometimes scientists get excited about their findings,too,and leak them to the press before they have been through a rigorous review by the scientists peers.As a result,the public is often exposed to late-breaking nutrition news st

32、ories before the findings are fully confirmed.Then,when the hypothesis being tested fails to hold up to a later challenge,consumers feel betrayed by what is simply the normal course of science at work.The Consumer Corner offers some tips for evaluating news stories about nutrition.n Scientists uncov

33、er nutrition facts by experimenting.Single studies must be replicated before their findings can be considered valid.New nutrition news is not always to be believed;established nutrition news has stood up to the test of time.The challenge of Choosing FoodThe variety of foods to choose fromTable 1-4Gl

34、ossary of food typesn basic foods milk and milk products;meats and similar foods such as fish and poultry;vegetables,including dried beans and peas:fruits;and grains.These foods are generally considered to form the basis of a nutritious diet.Also called whole foods.nenriched foods and fortified food

35、s foods to which nutrients have been added.If the starting material is a whole,basic food such as milk or whole grain,the result may be highly nutritious.If the starting material is a concentrated form of sugar or fat,the result may be less nutritious.nfunctional foods a term that reflects an attemp

36、t to define as a group the foods known to possess nutrients or nonnutrients that might lend protection against diseases.However,all nutritious foods can support health in some ways.nnatural foods a term that has no legal definition.nnutraceutical a term with no legal or scientific meaning,but someti

37、mes used to refer to foods,nutrients,or dietary supplements believed to have medicinal effects(see Chapter 11).Often used to sell unnecessary or unproved supplements.nfast foods restaurant foods that are available within minutes after customers order them-traditionally,hamburgers,french fries,and mi

38、lkshakes;more recently,salads and other vegetable dishes as well.These foods may or may not meet peoples nutrient needs well,depending on the selections made and on the energy allowances and nutrient needs of the eaters.norganic foods understood to mean foods grown without synthetic pesticides or fe

39、rtilizers.In chemistry,however,all foods are made mostly of organic(carbon-containing)compounds.(See Chapter 14s Consumer Corner for details.)n partitioned foods foods composed of parts of whole foods,such as butter(from milk),sugar(from beets or cane),or corn oil(from corn).Partitioned foods are ge

40、nerally overused and provide few nutrients with many calories.nprocessed foods foods subjected to any process,such as milling,alteration of texture,addition of additives,cooking,or others.Depending on the starting material and the process,a processed food may or may not be nutritious.nstaple foods f

41、oods used frequently or daily,for example,rice(in the Far East)or potatoes(in Ireland).If well chosen,these foods are nutritious;certainly,they should be.A nutritious diet follows thea,b,c,m,v principles:n adequacyn balancen calorie controln moderationn varietyWhat Exactly Is a Nutritious Diet?nA nu

42、tritious diet has five characteristics.One is adequacy:the foods provide enough of each essential nutrient,fiber,and energy.Another is balance:the choices do not overemphasize one nutrient or food type at the expense of another.The third is calorie control:the foods provide the amount of energy you

43、need to maintain appropriate weight-not more,not less.The fourth is moderation:the foods do not provide excess fat,salt,sugar,or other unwanted constituents.The fifth is variety:the foods chosen differ from one day to the next.nadequacy the dietary characteristic of providing all of the essential nu

44、trients,fiber,and energy in amounts sufficient to maintain health and body weight.nbalance the dietary characteristic of providing foods of a number of types in proportion to each other,such that foods rich in some nutrients do not crowd out of the diet foods that are rich in other nutrients.Also ca

45、lled proportionality.ncalorie control control of energy intake;a feature of a sound diet plan.nmoderation the dietary characteristic of providing constituents within set limits,not to excess.nvariety the dietary characteristic of providing a wide selection of foods-the opposite of monotony KEY POINT

46、 A well-planned diet is adequate in nutrients,is balanced with regard to food types,offers food energy that matches energy expended in activity,is moderate in unwanted constituents,and offers variety.Foods of high nutrient density form the foundation of such a diet.nnutrient density a measure of nut

47、rients provided per calorie of food.Self Check questions 1.Studies of whole populations that reveal correlations between dietary habits and disease incidence are referred to as:n a.case studies b.intervention studiesn c.laboratory studies d.epidemiological studies 2.Energy-yielding nutrients include

48、 all of the following except:n a.vitamins b.carbohydrates c.fat d.protein3.Organic nutrients include all of the following except:n a.minerals b.fat c.carbohydrates d.proteinn 4.One of the characteristics of a nutritious diet is that it provides no constituent in excess.This principle of diet plannin

49、g is called:n a.adequacy b.balance n c.moderation d.variety 5.A slice of peach pie supplies 357 calories with 48 units of vitamin A;one large peach pro vides 42 calories and 53 units of vitamin A.This is an example of:n a.calorie control b.nutrient densityn c.Variety d.essential nutrients6.Heart disease and cancer are due to genetic causes,and diet cannot influence whether they occur.T FControversy 1nIDENTIFYING VALIDnNUTRITION INFORMATION