Presentation on theme: "Chapter 2 Guidelines for Designing a Healthy Diet"— Presentation transcript:
1 Chapter 2 Guidelines for Designing a Healthy Diet
2 Chapter Outline Diet planning principles (2.1) Evaluating nutritional health (2.2, 2.3)Levels of nutritional statusDeficienciesFood Guides – skip pages 53-59Using My Plate (2.4 & Myplate.gov)Nutritional recommendations – DRI (2.5)Science behind nutritional research (2.6)Food labels (2.7)Health Claims
3 Planning a Healthy Diet Adequate Diet is a diet that provides enough energy to maintain a healthy diet and provides nutrients needed for optimal healthGeneral philosophy for an adequate diet….Eat a variety of foods in moderation.
4 Diet-Planning Principles (5) BalanceVarietyNutrient densityEnergy density – Kcal controlModeration
5 Diet-Planning Principles BalanceDiet that provides enough, but not too much of each type of foodDon’t want overeating of one food type to “crowd” out intake of other nutrients….
6 Diet-Planning Principles Variety - Diet that includes a wide selection of foods within each food groupEat a variety of fruits, not just orangesWhy?Variety within the fruit and vegetable groups has the added bonus of increasing the variety of phytochemicals in your diet.
7 PhytochemicalsPhytochemicals – substances in plants that may contribute to healthExamples – see page 12Functional Foods – foods that provide health benefits beyond those of the known nutrients
8 Diet-Planning Principles Nutrient DensitySelect foods that provide the most nutrients for the least number of calories (nutrient dense foods)Skim milk versus soda (page 40)Foods with few nutrients and many calories are sources of empty calories.
9 Diet-Planning Principles Energy Density - Kcal ControlFoods with low-energy density have low kcal per gram, page 41Can eat “a lot” without many caloriesSelect foods with low energy density for an intake that meets nutritional needs without excess kcal intake
10 Energy Density Measure of the kcal per gram of food _______ has the highest energy density of the 3 energy-yielding nutrients.Foods with a high energy densityprovide more kcal per gram than low density foods.
12 Diet-Planning Principles ModerationEat moderate (small) portion sizesModerate your intake of foods high in:Added sugarsSaltSaturated and trans fatsCholesterolAlcohol
13 Diet-Planning Principles (5) BalanceVarietyNutrient densityEnergy density – Kcal controlModeration
14 Levels of Nutritional Status Desirable/Ideal nutritionIntake is sufficient to meet daily needs and to keep nutritional stores full while maintaining a healthy body weight
15 Levels of Nutritional Status Borderline nutrition – a subset of undernutrition in textIntake is not sufficient to meet daily needsDrawing upon your storesBody is not prepared to handle times of stressIllness, pregnancy…May slows growth and development of fetus and growing child
16 Levels of Nutritional Status UndernutritionIntake does not meet daily caloric and nutrient needs and nutrient reserves are empty for some/all nutrientsThere is a decline in body functions due to the lack of nutrientsCan be life threateningMedical intervention required
17 Nutritional Deficiencies Covert vs. overt deficiencyCovert or sub-clinical – deficiency may be detected by lab tests, but not outward signs of the deficiencyOvert or clinical symptoms– outward signs of the deficiency
18 Nutritional Deficiencies Primary vs. secondary deficiencyPrimary – inadequate intake of the nutrientSecondary – body doesn’t absorb adequate amounts, excretes too much….Body “mishandles” the nutrientDiet history helps distinguish between these
19 Under-nourished Populations at increased risk: anyone living in povertyespecially infants, children, pregnant women, elderlyelderly in general, including those living in nursing homespregnant teensdrug and alcohol addictsindividuals with eating disordersanyone with prolonged illness, including hospital patients
20 Overnutrition Over-nutrition – 2 aspects excessive caloric intake that leads to obesityIncrease risk of obesity related diseasesheart disease, diabetes….overuse of vitamin supplements that leads to toxicity
21 Malnourished Comment on a commonly used term…. The term malnourished is most commonly used in reference to chronic under-nutritionIt can also be used in reference to anyone with chronic poor nutrition that results in failing health
22 Evaluating Nutritional Status Background - Personal HistorySESSocial history - living situation, marital statusPersonal and family health historyMedications, supplements takenEducational level…..Anthropometric data (A)Height and weightWaist circumference% body fat
27 Diet Planning Guides Food Group Plans Food Group Plans include: Foods within each food group provide similar nutrients and are from similar food sourcesPlan recommends the amount of food to be eaten in each food group.Food Group Plans include:USDA Food Guide (Pyramid/MyPlate)DASH diet
31 USDA Food Guide Assigns foods to 5 (6?) major food groups Recommends daily intake levels from each groupRecommendations vary depending on caloric needsRecommends weekly intake goals for several food groups.
32 My Plate - Grains 5-8 ounces bread, pasta, cereal, rice Half should be from whole grains1 slice of bread½ English muffin, bun½ cup cooked rice, pasta, cereal1 ounce dry cereal
43 Putting the Plan into Action Copyright 2005 Wadsworth Group, a division of Thomson Learning
44 MyPlate Physical Activity Adults should do at least 2 hours and 30 minutes each week of aerobic physical activity at a moderate levelOR1 hour and 15 minutes each week of aerobic physical activity at a vigorous level.
45 Science Of NutritionNutritional recommendations are based on scientific research.Recommendations attempt to define adequate intake.
46 Dietary Recommendations Dietary Reference Intakes (DRI)EAR - Estimated Average RequirementsRDA – Recommended Dietary AllowancesAI – Adequate IntakeUL – Tolerable Upper Intake LevelsAll based on nutritional research.
47 EAR and RDA Estimated Average Requirements Intake amount that appears to meet the needs of 50% of the populationAge, gender, “condition” basedSet after review of many research studiesRecommended Dietary AllowancesRDA is set to meet the needs of 98% of the population (without reaching toxic levels)
49 AI Adequate Intake (AI) AI = average amount of the nutrient that a group of healthy people consumeAI is set when there isn’t enough research to set an estimated average requirement (EAR) or RDAExamples: Vitamin D, water, fiber
50 UL Tolerable Upper Intake Level (UL) Maximum daily amount of nutrient that appears safe for most healthy peopleIntake above the UL is associated with toxicity symptomsMost often see with overuse of supplements or intake of many fortified foods
52 Other Recommendations Estimated Energy Requirements (EER)Caloric intake that will maintain energy balance in a healthy personValues given are for “reference” male and female who is fairly activeValues are not very useful for individuals!
54 Other Recommendations Acceptable Macronutrient Distribution Rangeor, recommended intake of energy yielding nutrients45-65% of caloric intake from carbohydrate20-35% of caloric intake from fat10-35% of caloric intake from protein
55 The Science of Nutrition One of the newest sciencesNew branch is nutritional genomicsStudy of the interaction of nutrients with DNA/genes and how those genes impact healthLike all sciences, nutrition is based on scientific research
57 Scientific Method Observations Questions Hypotheses Predictions Test hypotheses/predictionsAnalyze data and draw conclusionsShare resultsPage 64
58 Observations and Questions Make observations about diet and health. These observations lead to questionsFor example:The incidence of breast cancer is much lower in Japan than in the U.S.Diet in Japan is rich in…..while in U.S. diet is rich in ……Question?:
59 Develop Hypotheses and Make Predictions Hypothesis – tentative explanation of the observations or answer to the questionMake prediction – If the hypothesis is true what else is true?
60 Experiments Conduct experiments to test the predictions Easier said than done when people are involved!We’ll consider research designs later/soon.
61 One Experimental Design When possible, randomly assign subjects to either a control of experimental groupGoal is for two groups to be as similar to each other as possibleControl Group – either no change to diet or given a placeboExperimental group – diet changed or given a supplement
62 Experimental DesignCompare the health/lab values of the two groups before and after the diet change.Example – DASH diet study
63 Analyze results… Analyze results Draw conclusions about the validity of the hypothesisTest alternate hypothesesShare findingsPublish in nutritional journalsPresent findings at conferences
64 Common Research Designs Epidemiological study (observe)Cross-sectionalLongitudinalCase-control studyExperimental (intervene)Animal studiesHuman clinical trialsDouble blind studyLab studies
65 The Science of Nutrition 1. Epidemiological studiesStudy of populationsLook for correlations between dietary practices and health
66 Epidemiological Studies Cross-sectional - look for correlations between diet and health at a point in timeLongitudinal Studies - Follow a group of people (a cohort) over a period of timeLook for differences in diet that might account for the differences in health
67 Epidemiological Studies Case-control study – compare the diet of individuals with a condition to that of healthy individualsAgain, do not change their diet…..just observe it.Go to page 65 if not already there…
68 Human Experimental Studies Often called a Clinical StudyRandomly assign like people to either the experimental or control groupAlter the diet of experimental group as compared to a control groupCompare incidence of disease/lab values/ performance …. of two groups
69 Types of Clinical Trials Blind experimentsSubjects do not know which group they are inDouble blind experimentsNeither subjects nor the researchers know which group the subjects are in until after the experiment is overGoal is to avoid bias in the reporting/recording of the data.
70 Experimental Studies Animal Studies Controlled studies in lab setting using animalsAlter diet of experimental groupCompare health/lab values of control and experimental groupsBenefits? ….Drawbacks? ……
71 Experimental Studies Lab-Based Studies Also called in vitro studies Examine impact of a substance on living tissue in a “test tube”
73 The Science of Nutrition Size mattersGood studies have relatively large sample sizesPreliminary studies have smaller sample sizesPeer review mattersInformation in peer- reviewed research journals is much more credible than that in popular magazines, TV, Internet
74 Food Labels Ingredient list Serving size Listed by weight in product (most to least)Serving sizeSet by gov’t for each food typeNot the same as the MyPlate serving
75 Food Labels Nutritional content compared to Daily Values Daily Values are estimates of the needs of 2000 kcal per day consumerNot the same as RDA – why?
76 Food Labels Specific nutrition facts Kcal/serving Kcal from fat Total fat, grams and % Daily Value (DV)Grams saturated fat, % DVGrams trans fats – added 2006Cholesterol (mg and % DV)Sodium (mg and % DV)
77 Food Labels Nutrition Facts, cont’d Total grams carbohydrate Grams sugarGrams and % DV: fiberGrams protein% DV:Vitamin AVitamin CIronCalcium
79 Food Labels“Health” claims allowed on food labels are regulated by the FDALaw changed in 2003 to allow more health claimsMuch more confusing nowNow health claims with limited evidence can now be put on labels with a “disclaimer”/explanation.Pages 68/69