Dietary assessment

Dietary assessment is not easy. We often need good quality information on type of food used as well as the amount eaten. But there is no dietary assessment method that is suitable for all purposes, or all populations. For example, the intake assessment of a specific nutrient during a clinical intervention requires a different method than the estimation of habitual food intake in a healthy population.

A better understanding of the principles underlying each dietary assessment tool, with their advantages and disadvantages, will help you to choose the optimal method for your research question and target population. Other factors that you should consider are the available dietetics expertise in your research team, and factors such as planning and financial resources.

All tools available at the division of Human Nutrition and Health are based on validated self-reporting methodologies. 

The available tools are:

1. Compl-eat 
   Including a web-based  24-hour dietary recall tool to be completed by the participant or  an interviewer, a data entry module  for food records, and a nutrient calculation module
2. Eetscore 
   Short food frequency questionnaire to assess the diet quality according to the current Dutch Food-based Dietary Guidelines, with optional module to provide targeted dietary advice to the participant
3. Food Frequency Questionnaires
   Web-based tool to generate, administer and process Food Frequency Questionnaires (FFQ) 
4. Traqq app 
   A flexible dietary assessment app (iOS/Android) that can be used as a food record and a recall

Want to know more? View the video about our Dietary Assessment techniques

1. What is the purpose of the dietary assessment?
The most important step is to determine the exact purpose of the dietary assessment. Do you want to assess the intake of a specific food group, food or nutrient, or do you want to assess a complete dietary pattern? For example, if your aim is to assess the current dietary intake, a food record or one 24-hour dietary recall can be the best choice, but if your aim is to assess a habitual dietary pattern, multiple 24-hour dietary recalls or a food frequency questionnaire is better suited. Also, think about how the information will be used: is it a primary outcome of your study, a secondary outcome, a compliance measure, or  is it explorative? 

2. What type of information do you want to assess? 
Will the results be analysed at an individual or group level? For example, if you want to check if a population has an adequate intake, a group mean intake and distribution of intake is needed. For epidemiological studies, you want to rank individuals or classified them according to their intake to determine the association with a health-related outcome. If you want to know whether a patient’s intake and excretion of a specific nutrient is in balance, the absolute individual intake of the patient is needed.

3. What is the reference period?
The reference period of interest depends on the aim of the study. Sometimes it is more suitable to determine the actual intake, while in other cases the habitual intake is needed. For example, to check compliance to an intervention you want to know the actual  intake. But if you want to study the association between intake and a health related outcome, you may need the habitual intake over a longer time period.

4. What are the characteristics of the population?
The accuracy and applicability of the tools and methods can differ between  age groups, between men and women, but also within groups. For example, for healthy elderly all methods are suitable, while for frail elderly with cognitive disorders, methods that rely on memory cannot be used.
Note: Our Compl-eat, FFQ-tool and Eetscore tool are only suitable for a Dutch population with a Dutch dietary pattern.

5. Do you want to compare the data with other or previous studies? 
Data derived by different methods cannot be compared. Also, the outcomes of different FFQ’s are often not comparable. Therefore, the need for comparable results can be a reason to choose for a specific method.

6. How much resources are available?
It is most important to choose a method that is able to answer your research question. However, when more than one method is suitable the easiest and cheapest method can be chosen. For example, a web-based recall is less burdensome and cheaper for the researcher than a face-to-face recall by a trained interviewer.

See also an overview paper of currently available methods