FFQ-tool

The Dutch FFQ-tool is used to develop web-based Food Frequency Questionnaires (FFQ) that can be automatically administered and processed. A FFQ obtains the frequency, and in most cases the portion sizes of foods and drinks, consumed during a specific period, typically the past month or the past year.

Standard FFQs

We have a range of previously validated, ready-to-use FFQ’s available. The best suited FFQ depends on your research purpose and target population. Available FFQs are specifically developed and validated for assessing habitual dietary intake of specific food groups, foods or energy and nutrients.

The most important examples are:

• FQ18: a questionnaire to assess intake of energy, macronutrients, type of fatty acids, and dietary fibre.
• FQ13: a more comprehensive FFQ, that, in addition to the nutrients mentioned above, includes questions on foods to capture several important micronutrients, such as calcium, iron, vitamin B1, B2, B6 and B12.
• Score-FFQ: a comprehensive FFQ based on the FQ13, in addition this FFQ is able to score the Dutch Healthy Diet 2015 index and the WCRF/AICR Score.
• FFQ-NL: a comprehensive questionnaire with a reference period of one year to be applied in Dutch cohort studies.
• Children FFQ: a comprehensive FFQ that can assess the intake of energy, macronutrients and micronutrients, such as calcium, iron, vitamin B1, B2, B6 and B12, tailored for children from 2 till 12 years old.

Tailored FFQ’s

If a standard FFQ does not meet your research purpose or target population, it is also possible to develop a FFQ specifically tailored to your study. New FFQs are developed with the design function of the FFQ-tool. This function is based on a specific validated and published methodology. The methodology includes the following steps:

• The Dutch FFQ-tool generates a food list using data from a large survey, such as the Dutch National Food Consumption Survey.
• From this survey, the intake data of the target population are used to select the foods for the new FFQ
• These foods are selected based on their contribution to:
  • the level of intake of the nutrients of interest: only the most relevant foods are selected
  • their contribution to the between person variation of nutrient intake: the foods that differentiate most between the intake of individuals in the population are selected
• The contribution to the between person variation, is especially important if you are interested in the association of nutrient intake and a certain (health) outcome measure.
• After the foods have been selected, single foods are aggregated into food items, covered into questions, answer categories are added, and, if relevant, portion size questions are included.

Number of food items

• The number of foods that is included in a new FFQ mainly depend on:
  • The chosen size of contribution of the selected foods to the intake level or to the explained between person variance in the total diet. If your cut-offs are higher, more foods will be included, and the questionnaire will be longer.
  • The desired length of the questionnaire considering the purpose and the population. A full-length FFQ (FQ13) contains 163 food items, covers 95% of energy intake and takes around 30-45 minutes to fill in.

Implementing the FFQ

The standard available and newly developed FFQs can be distributed to the participants by the researcher via an email with login instructions. Participants will complete the FFQ via a web-based interface.

Processing of the data

During the development of the FFQ a specific food composition table for the FFQ is generated. This table includes the composition of all food items for energy and nutrients for which it was developed. It is calculated using the composition of the single foods based on the NEVO food composition database and their relative weighted contribution to the food item according to the survey. This food composition table is used to process the collected FFQ-data to a .CSV file, including the intake of the food items, energy and nutrients per individual per day. Processing the data will be done by our dietitians at the end of the study.

An additional data check can be performed by our dietitians. In this check the
reported data will be checked for possible over-and underreporting and will be
compared to a reference population.