Seminar - Dietary Assessment Methods Flashcards
What are dietary assessments?
A comprehensive evaluation to assess food consumption at a national, household or individual level
- used to estimate energy + nutrient intake
Why is it necessary to collect this type of information?
- Research + pop. health
- assess dietary adequacy of groups or individuals
- monitoring trends
- evaluate nutritional impact of dietary intervention
- assess possible relationship between diet + disease
- In sport + exercise / clinical settings
- help optimise dietary strategies or support dietary counselling
- dietary adherence assessment
- input for medical management (weight-loss clinic before surgery etc)
What are 3 methods of gaining this information?
- Recorded food intake - prospective
- 24 hour recall - retrospective
- Food frequency questionnaire - retrospective
Explain how ‘recording food intake’ is done
Via weighed intake or estimated intae (using portion sizes via household measures)
- record everything consumed for 3-7 days (stick to normal diet)
- household measures involves teaspoons, cups, volume, weight etc
Explain the advantages of recording food intake
+ does not depend on memory
+ can be detailed + precise
+ captures intake over several days
+ can estimate nutrient intake with good precision
Explain the disadvantages of recording food intake
- recording may influence eating behaviours as they feel they are being monitored
- requires intensive data entry
- high participant burden
- prone to under- or over-reporting
What is 24 hour recall as a method of dietary assessment?
Similar to food diary…
- delivered in 2 rounds - dietition asks question’s about what’s been eaten at breakfast, lunch, dinner + whether it was at home / out + then details of the foods
- probe them with ‘anything else’ etc
Explain the advantages of 24 hour recall
+ inexpensive
+ can be detailed
+ can be repeated in same individual over several occasions
+ appropriate for large scale surveys + in clinical settings
+ does not influence food intake
Explain the disadvantages of 24 hour recall
- memory dependent
- intensive data entry
- Prone to under/over-reporting
- requires a trained interviewer
Describe ‘food frequency questionnaires’ as a method of dietary assessment
Estimates habitual intake of foods or groups of foods
- it collects info on frequency + amount of consumption of specific items of food
- provides an estimate of habitual intake over a period of months / years
- consists of roughly 130 foods, 9 frequency categories
Explain the advantages of food frequency questionnaires
+ low participant burden
+ captures habitual food intake
+ quick data analysis due to standardised format
+ inexpensive for large pop. studies
+ method does not influence the respondent’s food pattern
Explain the disadvantages of food frequency questionnaires
- Limited detail (portion sizes, food prep details etc)
- Not useful for ‘absolute’ nutrient intake
- assumes a certain level of literacy
- limited by the listed food items
- relies on memory
How do researchers choose which dietary tool to use?
- Study objective - quantitative vs qualitative data
- Group in question - individual vs pop.
- Sample size - large or small
- What needs to be measured - past or current consumption
- Characteristics of individual - age, literacy, memory
- Resources available - low vs high
What are Atwater’s general factors?
Carbs - 4kcal/g
Protein - 4kcal/g
Fat - 9kcal/g
What are the macronutrient recommendations in terms of contribution to % energy intake?
What about for free sugars, saturated + trans-fatty acids?
Carbohydrate = 50%
Fats = 35%
Protein = 15%
Free sugar - not exceed 5%
Saturated fats = <11%
Trans-fats = <2%
What are dietary reference values?
DRVs are estimates of amount of energy and nutrients required by different groups of healthy people in a pop.
- group estimates not individual goals
- pop. focus - helps ensure public health strategies cover nutritional needs of most people
What is total daily energy expenditure made up of?
- Basal metabolic rate (resting)
- Thermic effect of food
- Activity energy expenditure
What is the Mifflin predicative equation?
Predicts resting metabolic rate
Males = (10 x weight[kg]) + (6.25 x height [cm]) - (5 x age[years]) + 5
Females = (10 x weight[kg]) + (6.25 x height [cm]) - (5 x age[years]) - 161
How is thermic effect of food + activity energy expenditure taken into account?
Will be given a factor of contribution from those systems and then multiply answer from Mifflin Equation by them
What are the advantages + disadvantages of Mifflin equations?
+ive - accessible + practical
+ive - predicts resting metabolic rate (RMR)
-ive - generalisation - equations may not be tailored for specific pops.
