DIETARY ASSESSMENT FOOD CONSUMPTION/DIETARY METHODS

• Dietary assessment


  A study or activity intended to measure the quantity and quality of diets of individuals or population or groups in a particular area for a given period of time
• Household food consumption


  Involves the collection of information on the quantity of food consumed as it enters the kitchen or used for the participation of meals which is in sufficient detail to permit calculation of nutritive value of the diet
• Food balance sheet (FBS)


  A rough estimate of food supplies available for consumption at the national level. It does not measure the amount of food consumed but the data from FBS are used in formulating agricultural policies, monitoring food changes and comparing food supplies with other countries
• Market database


  Sales of food from grocery and commercial food establishments. These are used to analyze trends in consumer purchases of food or food groups
• Family food account


  A simple running report of foods purchased and food expenditure for the family over a period of several weeks
• Strengths of family food account

  • Useful in checking trends in food purchases
  • Suitable for large samples
  • Can be used over relatively long periods
  • Less likely to lead to alterations in diet pattern
  • Relatively economical
• Food record


  Makes use of weighed inventory of foods on hand at beginning and end of the study period together with a day-to-day record (by weight) of food entering the home, with or without records of kitchen waste; if detailed enough, the method permits computation of nutrient values
• Strengths of food record

  • Does not depend on memory
  • Can provide detailed intake data
  • Can provide data about food/eating habits
  • Multiple-day more representative of usual intake
  • Reasonably valid up to five days
• Food list method


  Respondents are asked to estimate by weight, retail or unit or household measure of various foods consumed the last several days or just the previous day in which case, the method is called 24-hour recall
• Strengths of food list method

  • Relatively easy method
  • Can reach a bigger sample in less time
• Food record (individual level)


  Subject is asked to keep a record of types and amounts in households measures, of all food eaten during a given period; nutrient value of diet may be computed
• Strengths of food record (individual level)

  • Fairly reliable since it does not depend on memory
  • Useful in clinical dietetics where it is desirable to monitor food intake
• 24 or 28 hour recall


  Subject is asked to recall types and amounts of all food eaten during the previous 1 or 2 days; if well taken, may also be computed for nutrient value
• Strengths of 24 or 28 hour recall


  • Easy to obtain so that more subject can be covered in less time
  • Useful in describing usual diet pattern
• Weighed food intake


  Subject or a trained person weighs all food eaten during a given time period. Food is weighed after preparation, before it is eaten. Plate waste is also weighed
• Strengths of weighed food intake

  • Very reliable method
  • Useful when high degree of accuracy is required
  • Standard method in controlled or metabolic studies
• Food frequency questionnaire


  With a list of foods or food groups, information is obtained on the frequency of consumption of each food in the list, over a long period of time- months or year
• Strengths of food frequency questionnaire

  • Easy to administer
  • Machine readable
  • Relatively inexpensive for large scale studies
  • Data obtained more representative of usual intake vs food record or 24-hour recall
• Diet history

  Uses a combination of 24-hour recall and food frequency and in addition, collects information on factors affecting food intake
• Strengths of diet history

  • Useful in clinical setting
  • Provides basis for intervention
• Chemical analysis


  An aliquot portion of an exact duplicate of the meals eaten is taken for chemical analysis
• Strengths of chemical analysis

  • Most accurate method
  • Better than weighed food intake where nutrient content is calculated from food composition table
• Semi-quantitative food frequency questionnaire

  Are food frequency questionnaires that assess both frequency of consumption as well as portion sizes, used in studies that relate diet and disease, e.g. cancer and CVD and in studies of vitamins and mineral consumption, allows quantification of usual amount of food intake, thus nutrient intake can be done
• Multiple pass approach 24 hour recall


  Method of collecting food intake for the past 24-hours and enhanced with probing questions on food recalled during the interview before
• Telephone interviews


  Inquiry on food intake is made by telephone or data that are left on a recording device or answering machine
• Visual records

  Development of photographs or video methods to record dietary intake
• Computerized techniques

  Uses food recording electronic device to record dietary intake
• Surrogate sources


  Interview taken from spouse, children, close relatives, friends for elderly persons or patients with hearing or memory problem
• Nutrient adequacy ratio (NAR)

  An index of the adequacy of nutrient intake based on the requirement (RENI/RDA) for the nutrient. NAR= Subjects daily intake of nutrient / RDA or RENI of that nutrient. Results are expressed as percentage of RENI for specific nutrients; diets should not be classified as "deficient" or "inadequate"; however, the more the habitual intake falls below the RDA and the longer the duration of low intake, the greater the risk of intake are used as the "cut-off" are defined as "at-risk". Usually, two-thirds of recommended nutrient intake has been used
• Probability approach to evaluating nutrient intake


  Predicts the number of individuals within a group with nutrient intakes below their own requirements and hence, provides an estimate of the population at-risk
• close relatives, friends for elderly persons or patients with hearing or memory problem

  Target audience for evaluation of food consumption data
• Quantitative evaluation


  Involves computations of nutrient content of food consumed using appropriate food composition tables
• Nutrient Adequacy Ratio (NAR)

  Index of the adequacy of nutrient intake based on the requirement (RENI/RDA) for the nutrient
• Results of NAR


  Expressed as percentage of RENI for specific nutrients; diets should not be classified as "deficient" or "inadequate"; however, the more the habitual intake falls below the RDA and the longer the duration of low intake, the greater the risk of intake are used as the "cut-off" are defined as "at-risk". Usually, two-thirds of recommended nutrient intake has been used.
• Probability approach to evaluating nutrient intake


  Predicts the number of individuals within a group with nutrient intakes below their own requirements and hence, provides an estimate of the population at-risk or the prevalence of inadequate intakes; has been used for iron, Vit. C, thiamin, riboflavin and calcium
• Index of Nutritional Quality (INQ)


  Represents the quality of a nutrient in a food, meal or diet; designed to evaluate the adequacy of meals and diets of individuals and can therefore be used for individual counseling
• Standard Deviation or Z-scores


  A measure of the individual's nutrient intake in relation to the distribution of corresponding nutrient intake of the group; useful in monitoring individuals relative to a group.
• Qualitative evaluation

  Focuses on types of foods consumed
• Frequency (or infrequency) of consumption of certain foods/food groups


  Can suggest possible dietary inadequacies, e.g. Infrequent or Non-Consumption of yellow and green leafy vegetables together with infrequent or non-consumption of eggs and milk suggests inadequate vitamin A intake, Infrequent Consumption of fruits and vegetables in general suggests inadequate intake of vitamin C
• Dietary Diversity Score


  Based on the assumption that the more varied the diet, the better is its nutritional quality. Useful in describing overall quality of diet, but does not identify "problem" nutrients. Method still needs to be refined/standardized. Standards for evaluation still need to be validated.