W6 - Dietary Assessments

Question 1

List the dietary assessment methods

Answer 1

Total energy (Calorie) intake

Macro +/or micronutrient intakes

Consumption of ind. foods or food groups

Dietary patterns

Dietary behaviour i.e timing of food consumption

Question 2

List the dietary assessment tools

Answer 2

Dietary recall

Food Record

FFQ

Biomarkers

Question 3

Name an advantage to dietary recall + food records

Answer 3

Can be easily applied to diverse groups w/ a wide range of eating habits.

Question 4

What do dietary recall + food records provide?

Answer 4

Provides detailed info of food consumption over a specific period of time.

Question 5

How are 24hr recalls conducted?

Answer 5

In-depth interview
OR
Open-ended questionnaire.

Question 6

What is required from the interviewer in the 24hr recall?

Answer 6

For them to be trained + knowledgeable on how they ask the Qs to ensure they’re not effecting the answer.

Question 7

Strengths to 24hr recalls

Answer 7

Minimal subject burden - i.e easy for subject to do.

Question 8

Limitations to 24hr recall

Answer 8

Info depends on subjects memory

Risk of recall bias

Time consuming

Expensive to analyse + interpret

Question 9

Strengths to weighted food record

Answer 9

Min reliance on subjects memory if food is recorded at time of consumption.

Provides weighed portion - no reliance on estimation.

Detailed descriptions of foods consumed + all occasions are provided.

Question 10

Limitations to weighed food record

Answer 10

Subjects must be trained in order to provide accurate data.

Ind. must be numerate + literate.

Weighing + recording food eaten away from home can be difficult.

Ind. may alter diet to make it easier to record or conceal poor diet.

Question 11

Recall + records limitations

Answer 11

Focused on ST intake - not useful for investigation of chronic diseases.

To measure an avg intake, need multiple 24hrs.

Req a lot of time

Repetition can influence their diet:

• Intentionally to avoid a burden i.e more basic meals so less ingredients to record.
• May chose to not report an intake.

Question 12

Define a nutritional biomarker

Answer 12

Any biological specimen that is an indicator of nutritional status w/ respect to intake or metabolism of dietary constituents.

Question 13

What do nutritional biomarkers provide?

Answer 13

Objective info on dietary intake - thus overcoming many limitations of self-reported dietary intake.

Question 14

What are the types of nutritional biomarkers?

Answer 14

Biomarkers of dietary exposure

Biomarkers of nutritional status

Question 15

Biomarkers of dietary exposure

Answer 15

Assess dietary intake of different nutrients, foods, food groups or diet patterns.

Question 16

Biomarkers of nutritional status

Answer 16

Assesses intake + metabolism of. nutrients + pot effects from disease processes.

Question 17

List the main classes of biomarkers

Answer 17

Recovery biomarkers

Concentration biomarkers

Predictive biomarkers

Replacement biomarkers

Question 18

Recovery biomarkers

Answer 18

Based on the metabolic balance between intake + excretion during a fixed period of time.

Question 19

What are recovery biomarkers used for?

Answer 19

To assess absolute intake

i.e urinary nitrogen + urinary potassium

Question 20

Concentration biomarkers

Answer 20

Based on the conc of the marker + used for ranking of intake.

NOT used to determine absolute intake as they’re related to metabolism, personal characteristics + lifestyle factors.

i.e plasma vitamin c

Question 21

Predictive biomarkers

Answer 21

For biomarkers with incomplete recovery but a stable + time-dependent high correlation w/ intake.

Question 22

What can predictive biomarkers predict

Answer 22

Dietary intake i.e urinary sucrose + fructose.

Question 23

Replacement biomarkers

Answer 23

Serve as a proxy for intake.

When it’s not possible to capture due to info in nutrient databases is unsatisfactory or unavailable.

i.e Sodium

Question 24

Are biomarkers of nutritional status nutrients?

Answer 24

Not necessarily

Question 25

When are methylmalonic acid levels elevated?

Answer 25

In a deficiency state of vitamin B12

= Methylmalonic acid is a biomarker of vitamin B12 status.

Question 26

When are homocysteine levels elevated?

Answer 26

In the absence of enzymes to metabolise it to cysteine or methionine.

The enzymatic reactions req vitamins incl. vitamin B6, B12 + folic acid, thus elevated homocysteine is a biomarker for these nutrients.

Question 27

What can enzymatic activity serve as?

Answer 27

Nutritional biomarkers.

Question 28

Strengths to biochemical markers

Answer 28

Highly correlates to dietary intake levels

Free of bias

Independent of memory

Question 29

Limitations to biochemical markers

Answer 29

Expensive

Difficult to assess intake of food groups

Sometimes affected by disease

Question 30

What happens when combining subjective dietary assessment tools with biomarkers

Answer 30

Dietary intakes can be estimated

• These estimates are more valid as 1 method can account partly for the disadvantages of the other method.
  i. e biomarkers account for dietary misreporting + self-reporting methods account for errors associated w/ the metabolism of nutrients.

Question 31

What happens when combining subjective dietary assessment tools with biomarkers

Answer 31

Dietary intakes can be estimated

• These estimates are more valid as 1 method can account partly for the disadvantages of the other method.
  i. e biomarkers account for dietary misreporting + self-reporting methods account for errors associated w/ the metabolism of nutrients.

Question 32

List biological specimens used for biomarker testing

Answer 32

Serum + plasma

Erythrocytes

Adipose tissue

Urine

Hair + nails

Cheek cells - Buccal swab

Stool

Question 33

Cond. that impact specimen result validity

Answer 33

Time of day

Seasonal variation

Physiological state

Storage

Question 34

What does choosing the dietary assessment tool depend on?

Answer 34

Objective of study

Study design

Demographic characteristics of pop

Available resources