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DIETARY ANALYSIS

Terms in this set (24)

1)
Involves weighing or estimating the amount of food or drink immediately before and after eating (i.e., leftovers).
- Includes cooking method, brand name, location purchase etc.
- Participants usually record this in a food diary or Dictaphone.
- Estimated records may include photographs to estimate portion size. (if you give client a plate, then you can look at their portion sizes if you know the size of the plate)

- Generally considered the most accurate method of dietary assessment of individuals currently.
- Widely used in research, as well as in diet surveys and large-scale studies of diet and health
- Usually requires at least 2 weekdays and 1 weekend day (because we find dietary habits change)
- more days can provide more comprehensive assessment
- very labour intensive so more days may decrease accuracy (less detail from clients)

EPIC Use of food record
EPIC (European Prospective Investigation of Cancer)
Large-scale study. Looked at inks between die and cancer. Sent out food diaries to lots of people- provided instructions on how much info they needed to provide (had to weigh food etc).

2)
POSITIVES:
- does not rely on memory (recorded in real time)
- time period is defined (restricted time to improve accuracy)
- can be highly accurate (portions can be weighed- if weighed accurately)
- 2 or more days provide info on day-to-day variation in intake
- procedure can be automated (e.g. apps like myfitnesspal)

NEGATIVES:
- may effect food choices (may alter their diet for assessment)- choose foods that are easier to record OR choose foods they think the nutritionist would want them to eat.
- food consumed outside the home may be less accurately recorded (e.g. restaurants)
- time consuming
- honesty?

3)
CONCLUSIONS:
Far from perfect but probably the best method of dietary assessment available if:
- Participants are properly coached in how to
complete food records accurately.
- Time required to complete food record is as short
as possible.
- Acknowledgement is made that results are only
estimates. (you can recognise patterns in peoples
diet to make changes)
1)
Pro's
· Less burden on the participant than the food record method
· Time period is defined
· Food intake can be quantified
· Procedure does not alter participants eating habits
· Interviewer can probe participant to ensure accurate recall
· Response rates are usually high
· Two or more days provide info on day-to-day variation in intake
· Procedure can be automated and administered by mail

Con's
· Relies on memory and honesty
· Portion size is difficult to estimate accurately
· Intakes tend to be underreported compared to other methods
· Usual intake of an individual cannot be assessed from one day's intake
· Interviewer needs to be highly trained
· Procedure may be more difficult for certain population groups e.g. children

2)
Food frequency questionnaire.
Does not require any specialist knowledge, skills or equipment. Response rates are high and burden is low for the participants.

3)
· Participants may forget to record certain items
· Participants may decide not to consume a meal or snack due to the inconvenience of weighing and recording it.
· Participants may alter their diet in order to hide their true dietary intake.
· Participants may alter their diet out of convenience
· Issues with the analysis of the foods consumed
· Differences in bioavailability, which may mean certain individuals obtain less nutritional value from a food-type than other people.

4)
Systematic error is when a method of data collection typically results in an over or underestimation of the true value. Importantly, systematic error is always in the same direction, i.e. always over or always under estimated.
It is typical for a dietary assessment to under-estimate true intake for many of the reasons answered in questions above. Therefore, nutritionists need to understand that a dietary assessment is only ever an estimation and likely an underestimation. Repeating dietary assessment is important as this can reveal changes in dietary intake or may highlight practises that can be improved. However, the absolute values obtained should not be relied on fully.

5)
weighed food record.