dietary assessment Flashcards
comprehensive evaluation to assess food consumption at a national, household or individual level
can be used to estimate energy and nutrient intake
nutrition and population health
info colllected to:
assess dietary adeauacy (or shortcomings) of groups or individuals
monitoring trends
evaluate nutritional impact of a dietary intervention
assess possible relationship between diet and disease
sport and exercise clinical setting
why do we collect dietary data?- S+E clinical setting
help to optimise dietary strategies or support dietary counselling
dietary adherence assessment
input for medical management
direct assessment methods- prospective
prospective=current
recording food intake during a specified period of time eg food diaries- weighted intake
requires an individual to record everyhting consumed over a specified period - individual should stick to usual diet
food record- weighed intake vs estimated intake
quantifying intake when eating out- use pics to compare portions
misreporting food intake is very common in food diary studies- ps may get bored of filling out diary and may show bias
food record- prospective
advantages- doesnt depend on memory, can be detailed and precise, captures intake over several days, can estimate nutrient inrake with good precision (weighed)
disadvantages- by recording the eating behaviour, it may be influenced (hawthorne effect), intensive data entry, high participant burden, prone to under and over reporting
hawthorne effect- changing behaviour when you know you are being observed
direct assessment- retrospective
remembering foods consumed previously eg diet history- 24 hour recal, food freq questionariire
dietary recall
advantages- inexpensive, can be detailed, can be repeated in the same individual on several occasions, appropriate for large scale surverys and in clinacal settings, doesnt influence food intake
disadvantages- memory dependent, one recall is not always representative (weeknd vs weekday), intensive data entry, prone to under and over reporting
food frequency questionnaire
estimates habitual intake of foods or groups of foods
FFQ collects info on the freq and amount of consumption of specific items of food and drink
ps are given a list of items with a selection of options reporting the frequency or consumption of each food item
mostly generate data on foods rather than nutrients
FFQ adv/ dis
retrospective
adv- low p burden, captures habitual intake, quick data analysis due to standardised format, inexpensive for large population studies, reduced risk of bais as doesnt affect food intake
dis- may not capture portion sizes accurately, not useful for estimating absolute nutrient intake, assumes a certain level of literacy, limited by certain foods on list
choice of dietary assessment tool
study- objective, level of precision required, what needs to be measured
groups in question- inidivudal/ population
characteristics of indivudal
sample size
resources available- money, time, staff
atwater factors
if the macronutrient gram quantities are known, energy content can be calculated
macronutrients are expressed as a % of total energy intake
AF- uses single factor for energy yielding substances
carb- 4kcal/g
protein- 4kcal/g
alcohol- 7kcal/g
fat- 9kcal/g
dietary reference values
DRVs are a series of estimates of the amount of energy and nutrients needed by different groups of healthy poeple in the population
DRVs are estimates of teh requirements for groups of people and are not recommendations or goals for individuals
estimating energy requirements
composed of 3 components
resting metabolic rate
active energy expenditure
thermic effect of food (TEF)
predictive equations
accessible and practical way to assess EE of an individual or athlete
predict RMR/BMR from factors such as age, height, weight, lean body mass
weakesses- may not be designed specifically for certain populations eg athletes
mifflin predictive equations- would be given in exam- gives you RMR (REE)
can then calculate estimated dietary energy requirements-used to estimate resting energy expensiture:
- physical activity (PAL) for moderately active individuals- value of 1.6 for females or 1.7 for males can be applied to REE
- thermic effect of food- typically 10%, factor of 1.1 can be applied to REE
