Food Frequency Questionnaire conversion

The food frequency questionnaire (FFQ) is a retrospective method for assessing food consumption, in which a pre-defined list of foods is registered in relation to how often (and, in some versions, how much) they were eaten over a specific period of time.

The first Portuguese Food Frequency Questionnaire was developed by the Nutritional Epidemiology research team at ISPUP. This questionnaire originally included a list of 86 foods or food groups and nine frequency categories, to be reported regarding the last 12 months. This questionnaire was validated for the adult population by comparing the information reported in the questionnaire with 7-day dietary records in 4 seasons of the year, as well as with adipose tissue samples from the buttock region. The questionnaire was also validated in pregnant women and adapted for adolescents from 13 years of age.

The FFQ has two versions: one for self-completion by the participant (requires a higher level of literacy) and one to be applied by an interviewer, which has an extra section for recording the portions consumed (equal to, higher or lower than the standard average portion described).

This questionnaire is currently being revised in order to update it using the food consumption data obtained in the last National Food and Physical Activity Survey, carried out on a representative sample of the Portuguese population.

How is the quantification of food and nutrient consumption carried out?

The quantification of food consumption is obtained by multiplying the reported frequency of consumption for each item by the respective average standard portion, in grams, and by a seasonal variation factor for foods consumed in specific seasons. The conversion of foods into nutrients is carried out using a compilation of databases on the nutritional composition of foods: the Food Processor Plus computer programme (ESHA Research, Salem, Oregon), with nutritional information from the food composition tables of the United States Department of Agriculture, adapted to typical Portuguese foods, information from the Portuguese Food Composition Table, but also from other European countries and specific bromatological dosages of some nutrients.

We have assumed a social responsibility in this area, providing this food frequency questionnaire and the respective conversion of food consumption into nutrients and total energy free of charge within the scope of academic work carried out. However, its use requires prior authorisation, which should be requested to the following email address:

For work carried out outside the academic sphere or aimed at populations with specific eating habits (for example, requiring an extensive listing in the “Other Foods” section), the conversion of the FFQ is subject to a quotation.

Please contact us for a quotation.