Dietery Assessment Methods

Simplified information about dietery assessment methods when conducting epidemiological research

1. Presented By: Mona Mohammed Ali Dietary Assessment Methods 7/3/2021 1

2. Diet is a major lifestyle-related risk factor of various chronic diseases . Dietary intake can be assessed by subjective report and objective observation. Subjective assessment is possible using open-ended surveys such as dietary recalls or records, or using closed-ended surveys including food frequency questionnaires. Each method has inherent strengths and limitations 7/3/2021 2

3. D uplicate diet approach by a trained research staff. Food consumption record. Nutritional biomarkers N o information on how foods were consumed by each individual within household or about foods consumed outside the home were collected ! DIETARY ASSESSMENT BY OBJECTIVE OBSERVATION : 7/3/2021 3

4. T he 24-hour dietary recall ( 24HR). Dietary record ( DR). D ietary history. FFQ DIETARY ASSESSMENT BY SUBJECTIVE REPORT: 7/3/2021 4

5. Is a dietary assessment tool that consists of a structured interview in which participants are asked to recall all food and drink they have consumed in the previous 24 hours. It may be self-administered T ypically requires 20 to 30 minutes to complete a single day recall . 24-hour Diet R ecall: 7/3/2021 5

6. Detailed data about food preparation methods, ingredients used in mixed dishes, and the brand name of commercial products may be required The amounts of each food consumed are estimated in reference to a common size container (e.g., bowls, cups, and glasses), standard measuring cups and spoons, a three-dimensional food model, or two-dimensional aids such as photographs 24-hour Diet Recall: 7/3/2021 6

7. ADVANTAGES : A relatively minimal burden is imposed on respondents M easure intake with less bias than food frequency questionnaire . 24-hour Diet Recall: 7/3/2021 7

8. LIMITTATIONS: All information depends on the respondents’ memory and the skills of a well-trained interviewer to minimize recall bias Affected by reactivity . A poor method for measuring intake for food or drink with a high day-to-day variability. Unsuitable for large scale studies due to its time, literacy, and economic constraints. Used less frequently in pregnant women [ 24-hour Diet Recall: 7/3/2021 8

9. A food record (also called a food diary) is a self-reported account of all foods and beverages (and possibly, dietary supplements) consumed by a respondent over one or more days (i.e., an n-day food record ). It is a prospective open end survey. 7/3/2021 9 Dietary Record:

10. A new generation of records that takes advantage of recent technological advances is being developed. These include applications for smartphones and Internet users, and wearable photography devices 7/3/2021 10

11. ADVATAGES: collects data by subjects’ self-record at the time the food are eaten, thus minimizes reliance on a subjects’ memory. they are used as a reference instrument to validate or calibrate estimates from other less-detailed assessment instruments, such as a FFQ. used to examine relationships between some factor and diet in which diet is the dependent variable Used to examine relationships between diet and health or other variables, in which diet is the independent variable Dietary Record: 7/3/2021 11

12. LIMITATIONS : Focused on short-term intake. Reactivity is known to affect estimates T he open-ended format that requires considerable efforts in the course of data collection, entry, and analyses The requirements of completing a food record may limit participation in some groups, leading to potential selection bias . Quality of data may decline with increased number of days reported . 7/3/2021 12 Dietary Record :

13. The FFQ is an advanced form of the checklist in dietary history method, and asks respondents how often and how much food they ate over a specific period Presenting about 100 to 150 foods, this questionnaire takes 20-30 minutes to complete and can self-administered or collected via interview. 7/3/2021 13 F00d Frequency Questionnaire:

14. S hould be developed specifically for each study group and research purposes because diet may be influenced by ethnicity, culture, an individual’s preference, economic status, etc. The utility of questions in FFQs about portion size has been controversial. S hould be evaluated for their accuracy before being used as a dietary assessment tool in studies . Data can be linked to a database to yield information about total dietary intake. 7/3/2021 14 FFQ (cont.):

15. E nables the assessment of long-term dietary intakes in a relatively simple, cost-effective, and time-efficient manners . May be better than short-term instruments [24HR ] at assessing intake of episodically consumed foods because they attempt to directly capture usual intake over a period of time. 7/3/2021 15 FFQ : ADVATAGES :

16. 3. Are commonly used as the main dietary assessment instrument in large prospective studies. 4. Are the only practical methods for capturing diet in retrospective case-control studies . 7/3/2021 16 FFQ : ADVATAGES

17. Contains systematic error . Detailed information about food preparation, and contextual information about intake is lacking . Because an FFQ is composed of a pre-specified food list, any single FFQ may not reflect the eating patterns of a given population. Thus, the performance of a particular FFQ in a particular population may not reflect its performance in a different population. 7/3/2021 17 FFQs: LIMITATIONS :

18. Because of known systematic error in an FFQ, a less biased short-term instrument (e.g., 24HR) may be administered in an internal calibration sub-study to improve estimates of intake from an FFQ through regression calibration , allowing for a more accurate estimate of the association between diet and another variable. Alternatively, data from an external source (called an external calibration study ) can be used . 7/3/2021 18

19. 24HR DR FFQ Required technology Software, internet, etc. Software, internet, , mobile phone, application, etc. S kip algorithms, questions that ask for multiple details, pictures of foods, etc. Strengths Standardized data collection possible (reducing interviewer bias); likely reduce time and cost; improve feasibility Standardized, real-time data collection possible; likely reduce time and cost; improve feasibility Able to collect complex information and highly accurate data Limitations Inherent bias related to self-report Inherent bias related to self-report; requires participant training on how to use the technology Measurement errors related to methodology remain 7/3/2021 19

20. Used to obtain basic information about a limited number of foods and beverages consumed or dietary practices over a period of time, typically the past month or year. 2 types: 1.A short food frequency questionnaire, usually without portion size questions. 2.A behavioral questionnaire that asks about general dietary practices (for example, "Do you generally butter your bread?"). For both approaches, the questionnaire is usually self-administered, but can be interviewer-administered. Completing a screener usually requires less than 15 minutes 7/3/2021 20 Screener:

21. Data can be used to assess particular aspects of diet but not total dietary intake. Resulting estimates may be quantitative or qualitative, depending on the instrument. If data are linked to a nutrient composition database, nutrient intakes can be determined 7/3/2021 21 Screener:

22. Screeners can be used in retrospective case-control studies when interest is limited to a small number of dietary components rather than the total diet. Because of their limited scope, screeners are seldom used as the main instrument in prospective studies describing associations between diet and another factor . 7/3/2021 22 Screener:

23. Systematic error. The performance of a particular screener in a particular population may not reflect its performance in a different population. Use of procedures to score various dimensions of behavior developed in one population may not be appropriate in other populations. 7/3/2021 23 Screener:

24. 7/3/2021 24 THANKS