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Lec 2 community dietary assessment


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Lec 2 community dietary assessment

  1. 1. Community and Public HealthNutrition2-Dietary AssessmentPrepared by: Dr. Siham Gritly1Dr. Siham M.O. Gritly
  2. 2. What is dietary assessments• A dietary assessments are comprehensiveevaluation to assess food consumption atnational level, house hold level and a personsfood intake level.• It is one of the tool for nutritional statusassessment.• Dietary assessment includes;• food supply• production at the national level,• food purchases at the household level,• food consumption at the individual level.Dr. Siham M.O. Gritly 2
  3. 3. Dietary Assessment PrinciplesAdequacy; a diet that provides enough energyand nutrients to meet the needs according tothe recommended dietary intakes/ allowancesBalance : a diet that provides enough, but nottoo much of each type of food ( adequacy ofbasic 6 food groups)Dr. Siham M.O. Gritly 3
  4. 4. Variety; a diet that includes a wide selection offoods within each food groupNutrient Density : a diet that includes foods that providethe most nutrients for the least number of calories(nutrient dense foods)Moderation : A diet that limits intake of foods high insugar and fat (nutrient intake guidelines)Dr. Siham M.O. Gritly 4
  5. 5. There are different methods to assess dietaryintake;• 1- National food supply data (Food balancesheets)• 2-Household data• 3-Individual data• 4-Rapid Assessment Procedure RAPDr. Siham M.O. Gritly 5
  6. 6. Methods of assessing dietary intake• 1- National food supply data• The most commonly used to assess foodconsumption at national level are Food balancesheets;• Food balance sheets; provide data on foodavailability for consumption (i.e food supplywithin a country)Dr. Siham M.O. Gritly 6
  7. 7. Ref. FAO• It provides a comprehensive picture of thepattern of a country’s food supply during aspecific reference period, calculated from;• annual production of food,• changes in stocks,• imports and exports• and distribution of food over various useswithin the countryDr. Siham M.O. Gritly 7
  8. 8. Disadvantages of food balance sheet• Do not measure the food actually ingested bythe population(e.g. people of different socio-economic groups, ecological zones orgeographical areas within a country) but theyhave been used to compare the adequacy offood supply among countries to meetrequirements• Do not provide information on seasonalvariations in the total food supply.Dr. Siham M.O. Gritly 8
  9. 9. • 2-Household data• Household food consumption is the food andbeverages available for consumption at householdlevel ,• Disadvantages; excluding that eaten away from homeunless taken from the home.• It does not provide information on consumption offood by specific individuals within the householdlevel• food consumption /capita is calculated sometimesignoring the age or gender distribution in the HH.Dr. Siham M.O. Gritly 9
  10. 10. • Food consumption per capita can be calculated interms of;• income level,• number of meals eaten at home and away from home,• family size• region of the country;• Estimates of nutrient intake per capita are calculatedby multiplying the average food consumption data bythe corresponding nutrient values for the edibleportion of the food.Dr. Siham M.O. Gritly 10
  11. 11. National and household food consumptionImportance of household and foodconsumption surveys data• Data obtained through household and food consumption surveysare often the preferred source of food consumptionestimates for most analysts because;• 1- they provide more information on food consumptionthan food balance sheets do.• 2- the surveys collect data from the people who arepurchasing and eating the food,• 3- they can obtain information on the consumptioncharacteristics of children, elderly people, males, femalesand on rural compared with urban populations.Dr. Siham M.O. Gritly 11
  12. 12. for the assessment of under-nutrition prevalence in acountry; There are two main approaches.• 1-estimating the numbers of people whose dietaryenergy supply is likely to fall below a certainphysiologically needs.• 2-direct information on the nutritional status ofindividuals• Estimation of the distribution of energyconsumption among household is very valuableindicators for nutrients deficiencies.Dr. Siham M.O. Gritly 12
  13. 13. • 3-Individual data• Includes;• Food records,• 24 hr dietary recall,• FFQs, diet histories,• food habit questionnaires,• combined methodsDr. Siham M.O. Gritly 13
  14. 14. Assessment of individual intakesFood records• Dietary records• Record all foods and beverages consumed over aspecific time period (3-4 d)• Amount consumed determined by weighing witha scale or measuring volume using standard cupsand spoons• special foods may be recorded (fat, vitamin A,iron rich)• Total energy intake will require all foods to berecorded.Dr. Siham M.O. Gritly 14
  15. 15. Food Diary a food record is usually almost accurate if thefood eaten is recorded the same day; the individual’s nutrientintake is calculated and averaged at the end of the desiredperiod (usually 3-7 days) and then compared with dietaryreference intakes (DRIs)Meal Foods ( list ) AmounteatenHowpreparedWhere eaten(home, work,etc)BreakfastSnackLunchTeaDinnerFood supplements :Name…… (cans/d)Vitamins/minerals supplement:….Dr. Siham M.O. Gritly 15
  16. 16. Assessment of individual intakes24 hr dietary recall• The 24 hr recall requires individuals toremember the specific foods and amounts offoods they consumed in the past 24 hours;• the information is then analyzed by the personor professional.• Food intake per person or per consumptionunit is calculated taking into account the age ,sex and the number of family members.Dr. Siham M.O. Gritly 16
  17. 17. • method of preparation; (boiled/baked/fried);• brand name (commercial/ready to eat/parts eaten(whole item/half);• ingredients(if mixed dish, what ingredients used andamounts;• addition to foods ( was anything added to food duringpreparation or at the table; was any dressing added,cream or sugar)Dr. Siham M.O. Gritly 17
  18. 18. • Get an accurate and complete listing of allfood/drink individual consumed within last 24hrs• Questions asked:– What food/drink was consumed?– How much was consumed?– Time it was consumed?– How was it prepared?– How was it served?– Details of food (e.g low fat, 1%, whole, milkpowder, preparation, )Dr. Siham M.O. Gritly 18
  19. 19. Limitation of 24 hours recall• Relies on memory;• requires skilled interviewer;• does not reflect the usual dietary intake ;• tendency to over report low intakes and underreport high intakesDr. Siham M.O. Gritly 19
  20. 20. Assessment of individual intakesFFQs, diet historiesFF is a retrospective review of intake frequency– that is food consumed per day, week, per 15days, per month.Report usual frequency of consumption of eachfood item from a list of food items in referenceto a specified period (past wk/mo/yr)Dr. Siham M.O. Gritly 20
  21. 21. organizes foods into groups that have commonnutrientsFace to face interview, telephone or by selfadministrationDescribes dietary patterns or food habits notnutrient intakeSemi quantified tools can obtain information onportion size using household measuresDr. Siham M.O. Gritly 21
  22. 22. Example; Food Frequency QuestionnaireFood item > 1/d 1/d 3-6times/wk1-2/wk 2/mth orlessNeverBeefFishLiverPoultryEggsDried beansGreen leafyvegetablesEnter other foods not listed that areeaten regularly1.-------------2. -------------3. -----------Dr. Siham M.O. Gritly 22
  23. 23. Food Frequency QuestionnaireDr. Siham M.O. Gritly 23
  24. 24. Limitation of Food Frequency Questionnaire• Relies on memory;• requires complex calculations to estimatefrequencies;• requires literacy,• doe not quantify intakeDr. Siham M.O. Gritly 24
  25. 25. Example of semi quantitative FFQFood MediumservingServing How often ?S M L D W M Y NApples,applesauce1 or ½ cupBanana 1 mediumPapaya ¼ mediumWatermelon1 sliceOrange 1 mediumBel juice 6 oz glassCoconutwater4 oz glassBoroi ½ batiDr. Siham M.O. Gritly 25
  26. 26. • Semi quantitative food frequency questionnairesprovide the respondent with a food list.• Semi quantitative food frequency questionnairesestimate individual intakes quantitatively.• Nutrient intakes from semi quantitative foodfrequency questionnaires usually are overestimated.• Measures of usual energy intakes for accurategroups specified by sex and age obtained by othermethodsDr. Siham M.O. Gritly 26
  27. 27. • 4-Rapid Assessment Procedure RAP• focus groups to gather information on foodbehaviors, beliefs and intakes• Rapid assessment procedures (RAP) are a realityin international health, nutrition, and developmentplanning• Planning and implementing developmentprogrammes with peoples participation isconsidered one of the keys to sustainabledevelopment as suggested by experts.Dr. Siham M.O. Gritly 27
  28. 28. Estimating average intake of nutrients• Specification of portion size• Description of portion size – small, medium, large• Information on frequency and serving size allows forestimating nutrient intakes• Food list should contain foods that contribute to majority ofthe nutrients/specific in the diet (represent 75% of thenutrient intake –selected nutrients)• % adequacy of food groups• % adequacy of RDA for energy and nutrients includingmicronutrients• Used in epidemiological research to study diet diseaserelationshipsDr. Siham M.O. Gritly 28
  29. 29. • Epidemiology is a study of the relationshipbetween possible determining factors and thedistribution of the frequency of disease inhuman populationsDr. Siham M.O. Gritly 29
  30. 30. Estimated nutrient intakes must be compared withappropriate references;Dietary Reference Intakes (DRIs).The DRIs encompass four types of nutrientreference values, each with different uses• These values are used for planning andassessing diets include:• Estimated Average Requirements (EAR),• Recommended Dietary Allowances (RDA),• Adequate Intakes (AI),• Tolerable Upper Intake Levels (UL).Dr. Siham M.O. Gritly 30
  31. 31. • Estimated Average Requirement (EAR) -the amount of a nutrient that isestimated to meet the requirement ofhalf of all healthy individuals in a givenage and gender group.Dr. Siham M.O. Gritly 31
  32. 32. • Recommended Dietary Allowance(RDA) - the average daily dietary intakeof a nutrient that is sufficient to meet therequirement of nearly all (97-98%)healthy persons.• This is the number to be used as a goalfor individuals. It is calculated from theEAR.Dr. Siham M.O. Gritly 32
  33. 33. • Adequate Intake (AI) - only established whenan EAR (and thus an RDA) cannot bedetermined because the data are not clear-cutenough; a nutrient has either an RDA or an AI.• The AI is based on experimental data ordetermined by estimating the amount of anutrient eaten by a group of healthy people andassuming that the amount they consume isadequate to promote health.Dr. Siham M.O. Gritly 33
  34. 34. • Tolerable Upper Intake Level (UL) -the highest continuing daily intake of anutrient that is likely to pose no risks ofadverse health effects for almost allindividuals.• As intake increases above the UL, therisk of adverse effects increasesDr. Siham M.O. Gritly 34
  35. 35. Nutrition Recommendations from(WHO/FAO, 2003)• The World Health Organization (WHO/FAO)has assessed the relationships between diet andthe development of chronic diseases. Itsrecommendations include (look table next slide)Dr. Siham M.O. Gritly 35
  36. 36. Ranges of nutrient intake goals (WHO/FAO, 2003)Dietary factor Goal (% of total energy )Energy: sufficient to support growth, physicalactivity, and a healthy body weight(BMI between 18.5 and 24.9) and toavoid weight gain greater than 11pounds (5 kilograms) during adult lifeTotal fat: 15 to 30 percent of total energySaturated fatty acids <10 percent of total energyPolyunsaturated fatty acids 6 to 10 percent of total energyOmega-6 polyunsaturated fattyacids:5 to 8 percent of total energyOmega-3 polyunsaturated fattyacids:1 to 2 percent of total energyDr. Siham M.O. Gritly 36
  37. 37. Ranges of nutrient intake goals (WHO/FAO, 2003)Dietary factor Goal (% of total energy )Trans-fatty acids: <1 percent of total energyTotal carbohydrate: 55 to 75 percent of total energySugars: <10 percent of total energyProtein: 10 to 15 percent of total energyCholesterol: <300 mg per daySalt (sodium): <5 g salt per day (<2 g sodiumper day), appropriately iodizedFruits and vegetables: ≥400 g per day (about 1 pound)Total dietary fiber: >25 g per day from foodsPhysical activity: one hour of moderate-intensityactivity, such as walking, onmost days of the weekDr. Siham M.O. Gritly 37
  38. 38. Study DesignsA Cross-Sectional Surveysadapted from;Martin Eastwood. Principles of Human Nutrition; Second edition 2003 by BlackwellScience Ltd, a Blackwell Publishing Company• One of the most common types of population-level studies is the cross-sectional survey, a setof measurements of a population at a particularpoint in time.• Such data can be collected only to describe aparticular population’s intake.• for assessing risk of deficiency, toxicity, andoverconsumption;Dr. Siham M.O. Gritly 38
  39. 39. • Alternatively, data of this type of survey canbe used for surveillance at;• the national,• state,• local levels• Main objectives is;• to evaluate adherence to dietary guidelinesand public health programs;• and to develop food and nutrition policy.Dr. Siham M.O. Gritly 39
  40. 40. • Cross-sectional data also may be used forexamining associations between current dietand other factors including health.• caution must be applied in examining manychronic diseases believed to be associated withpast diet because the currently measured diet isnot necessarily related to past dietDr. Siham M.O. Gritly 40
  41. 41. • Some of the instruments, such as;• the 24-hour recall, are appropriate whenthe study purpose requires quantitativeestimates of intake.• Others, such as FFQs or behavioral indicators,are appropriate when qualitative estimates aresufficient—for example, frequency ofconsuming soda and frequency of eating fromfast-food restaurants.Dr. Siham M.O. Gritly 41
  42. 42. Case-Control (Retrospective) Studies• A case—control study design classifiesindividuals with regard to current diseasestatus (as cases or controls) and relates this topast (retrospective) experience.• the period of interest could be either;• the recent past (e.g., the year before diagnosis)• or the distant past (e.g., 10 years ago or inchildhood).Dr. Siham M.O. Gritly 42
  43. 43. • the 24-hour recall, are not useful inretrospective studies.• The food frequency and diet historymethods are well suited for assessing pastdiet and are therefore the only viablechoices for case—control (retrospective)studies.Dr. Siham M.O. Gritly 43
  44. 44. Cohort (Prospective) Studies• In a cohort study design, exposures of interestare assessed at baseline in a group (cohort) ofpeople and disease outcomes occurring overtime (prospectively) are then related to thebaseline exposure levels. In prospectivedietary studies, dietary status at baseline ismeasured and related to later incidence ofdisease.Dr. Siham M.O. Gritly 44
  45. 45. • For many chronic diseases, large numbers ofindividuals need to be followed for years beforeenough new cases with that disease accrue forstatistical analyses.• A broad assessment of diet is usually desirable inprospective studies because many dietaryexposures and many disease end points willultimately be investigated and areas of interestmay not even be recognized at the beginning of acohort studyDr. Siham M.O. Gritly 45
  46. 46. • In order to relate diet at baseline to the eventualoccurrence of disease, a measure of the usualintake of foods by study subjects is needed.• a single 24-hour recall or a dietary record for asingle day would not adequately characterize theusual diet of individual study subjects in a cohortstudy, such information could be later analyzed atthe group level for contrasting the averagedietary intakes of subsequent cases with thosewho did not acquire the disease.Dr. Siham M.O. Gritly 46
  47. 47. Intervention Studies• Intervention studies range from relatively small, highlycontrolled, clinical studies of targeted participants tolarge trial of population groups.• Intervention studies may use dietary assessment fortwo purposes:• (1) initial screening for inclusion (or exclusion) into thestudy• (2) measurement of dietary changes resulting from theintervention.• Not all intervention trials require initial screening.• For those that do, screening can be performed usingvery detailed instruments or less difficult instruments.Dr. Siham M.O. Gritly 47
  48. 48. Dietary Assessment Methods Commonly Used inDifferent Study Designsadapted from;Martin Eastwood. Principles of Human Nutrition; Second edition 2003 by BlackwellScience Ltd, a Blackwell Publishing CompanyStudy design MethodsCross-sectional 24-Hour recall, FFQ, briefinstrumentsCase—control(retrospective)FFQ, diet historyCohort (prospective) FFQ, diet history, 24-hourrecall, dietary recordIntervention FFQ, brief instruments, 24-hourrecallDr. Siham M.O. Gritly 48
  49. 49. Dietary Assessment in different studydesign• Questions that must be answered in evaluatingwhich dietary assessment tool is most appropriatefor a particular research need include thefollowing:• (1) Is information needed aboutfoods, nutrients, other food components, orspecific dietary behaviors?• (2) Is the focus of the research question ondescribing intakes using estimates of averageintake, and does it also require distributionalinformation?Dr. Siham M.O. Gritly 49
  50. 50. • (3) Is the focus of the research question ondescribing relationships between diet andhealth outcomes?• (4) Is absolute or relative intake needed?• (5) What level of accuracy is needed?• (6) What time period is of interest?• (7) What are the research constraints in termsof money, interview time, staff, and respondentcharacteristics?Dr. Siham M.O. Gritly 50
  51. 51. Food groupsThe foods have been classified in the followingfood groups• Cereals and their products• Starchy roots, tubers and their products• Legumes and their products• Vegetables and their products• Fruits and their products• Nuts, seeds and their productsDr. Siham M.O. Gritly 51
  52. 52. Food groups• Meat, poultry and their products• Eggs and their products• Fish and their products• Milk and their products• Fat and oils• Beverages• MiscellaneousDr. Siham M.O. Gritly 52
  53. 53. Easy way to count your calories (Measuresproviding 100 kcalDr. Siham M.O. Gritly 53Cereals : 30 g ( 1/5 cup)Bread : 40 g ( 2 slices)Pulses : 30 (2 Tbsp)Leafy vegetables (sak): 250 g ( 2small bunches)Other vegetables : 400 g (4 cups)Potato : 100 ( 1 cup)Nuts/oilseeds : 20 g (handful)Fruit : 150 g/ 1-2 fruitsMilk/Curd :150 ml ( 1 cup)Butter milk : 670 ml ( 4 cups)Channa/paneer/cheese : 30 g (1pkt)
  54. 54. Easy way to count your calories (Measuresproviding 100 kcal• Egg : 60 g ( 1 medium size)• Chicken : 90 g ( 3 small pieces)• Mutton (animal protein): 85 g• Fish (lean) 100 g• Fish (fatty) 60 g• Shrimp : 30 g• Prawn : 100 g• Sugar : 25 g ( 5 tsp)• spice : 40 g ( 6 tsp)• Oil/ghee : 10 g (2 tsp)• Butter : 15 g (1 TbspDr. Siham M.O. Gritly 54
  55. 55. Food composition tables• The conversion of food consumption tonutrient intake is a complex process whichrequires chemical analyses of the various foodconstituents,• food composition tables must include thefollowing.Dr. Siham M.O. Gritly 55
  56. 56. • Foods included in the table must becomprehensive and appropriate for thepopulation studied.• The number of nutrients included in the tablefor each food must be sufficient for the studyin question• The method of expression of amounts ofnutrients must be specified• Nutritionally appropriate methods must beused for the estimation of each nutrientDr. Siham M.O. Gritly 56
  57. 57. • The disadvantage of using food compositiontables and nutrient databases is that;• each value is the average of a limited numberof samples analyzed for each food.• Sampling errors are large, especially formixed food dishes and meals.• These add to the total error and variation inresults from dietary intake studies.Dr. Siham M.O. Gritly 57
  58. 58. Dr. Siham M.O. Gritly 58
  59. 59. • FOOD AND AGRICULTURE ORGANIZATIONOF THE UNITED NATIONS Rome, 2001• ANN M. COULSTON, CAROL J. BOUSHEY, MARIO G. FERRUZZI,NUTRITION IN THE PREVENTION AND TREATMENT OF DISEASETHIRD EDITION. Academic Press is an imprint of Elsevier•• Eastwood. Principles of Human Nutrition;Second edition 2003 by Blackwell Science Ltd, aBlackwell Publishing CompanyDr. Siham M.O. Gritly 59