Dietary assessment Methods (1C)

Question 1

Dietary assessment approach? input:

Answer 1

24h dietary recall(s)
Food Frequency
Questionnaire
Diet Record(s)–>

Quantitative
Assessment
of total/part
of diet–>

Coding of Dietary intake

Question 2

Dietary assessment approach? Processing:

Answer 2

Coding of dietary intake–>

food composition databases and daily nutrient intake–>

Question 3

Dietary assessment approach? output:

Answer 3

food composition databases and daily nutrient intake–>

dietary reference values and dietary evaluation

Question 4

Measurement error: Aim of a dietary assessment

Answer 4

• To estimate habitual (long term) intake

Question 5

Measurement error: Consequences of Measurement Error

Answer 5

• Underreporting will overestimate nutrient inadequacy

* May limit usefulness of associations with other markers and diseases.

Question 6

Measurement error: Sources of Measurement Error

Answer 6

• Non-response bias

• Respondent bias (Participant misunderstanding)
– Socially desirable responses (to avoid criticism)
– Socially acceptable responses (to seek praise)

• Interviewer bias
• Coding errors
• Limited food composition databases
• Respondent memory
• Incorrect portion size
• Day-to-day variation
• Impact of assessment method

Question 7

Dietary assessment methods: why?

Answer 7

• To measure usual intake

Question 8

Dietary assessment methods: Day to Day variation?

Answer 8

• Nutrient specific

* Seasonal/Weekday v wkd

Question 9

Dietary assessment methods: Methodology

Answer 9

• Dietary assessment methods have advantages & disadvantages

Question 10

Dietary assessment methods: Which is best?

Answer 10

• Situation specific

* Be aware of limitations

Question 11

24h Dietary Recall: advantages:

Answer 11

1. Provide very detailed information on eating patterns
2. Method cannot affect food choice
3. Quick & Easy
4. Minimal participant effort

Question 12

24h Dietary Recall: disadvantages:

Answer 12

1. Requires multiple days to
   estimate intake
2. Relies on participants memory and ability to estimate portion size

Question 13

24h Dietary Recall: error:

Answer 13

1. Systematic underreporting

2. Multiple days can still be poor estimates of usual intake

Question 14

24h Dietary Recall: application:

Answer 14

1. Individual Intake (multiple days)

2. Group Intake

Question 15

Food Frequency Questionnaire: advantages:

Answer 15

1. Method cannot affect food choice
2. Quick & Easy
3. May be more representative of
   usual intakes

Question 16

Food Frequency Questionnaire: disadvantages:

Answer 16

1. Less precise estimate than other methods

2. Appropriate foods / frequencies

Question 17

Food Frequency Questionnaire: error:

Answer 17

1. Systematic underreporting

Question 18

Food Frequency Questionnaire: application:

Answer 18

1. To identify food consumption
   patterns
2. Relationships between diets & disease state in large scale studies

Question 19

Food Records: advantages:

Answer 19

1. Provide very detailed
   information on eating patterns
2. Weighed/measured/household
3. Not dependent on memory

Question 20

Food Records: disadvantages:

Answer 20

1. Requires motivated participant
2. Time commitment - Experimenter
3. Requires multiple days to
   estimate intake
4. Recording affects food choices

Question 21

Food Records: error:

Answer 21

1. Systematic underreporting

2. Multiple days can still be poor estimates of usual intake

Question 22

Food Records: application:

Answer 22

1. Individual Intake (multiple
   days)
2. Group Intake
3. Relationship between nutrient intake and other variables

Question 23

Limitations of food tables: Analytical techniques:

Answer 23

• Fibre
– McCance & Widdowson Food Table
– Calculated non-starch polysaccharide
– Food Label – Enzymatic method (includes lignin) resulting in higher values

• Vitamins
– Dependent on terminology (micrograms, international units, equivalents)

Question 24

Limitations of food tables: Conversion Factors:

Answer 24

• Energy

* Protein – Nitrogen content x 6.25

Question 25

Limitations of food tables: Sampling Procedure

Answer 25

• UK specific or brand of product

Question 26

Limitations of food tables: Date of Testing

Answer 26

• Altered manufacturing process / Farming / Cooking/ seasons / storage

Question 27

Limitations of food tables: Bioavailability

Answer 27

• The proportion of a nutrient that can be absorbed/is available

Question 28

Limitations of food tables: Coding

Answer 28

• Missing nutrient values / Inappropriate food chosen / Incorrect entry / Portion size
• Your skills will be developed in workshops