Development and validation of a semi-quantitative food frequency questionnaire to assess dietary intake in Turkish...

To validate the original food frequency questionnaire in Turkish adult population.

The cross-sectional study was conducted in June and December 2008 and 2009, and comprised adults of either gender aged 30-70 years. All subjects were Caucasians and were native Turkish speakers. The food frequency questionnaire containing 229 most frequently consumed foods under 7 topics was used for data collection. It was completed twice and the 24-hour dietary recall four times in a year. In order to assess the validity of the questionnaire, Pearson correlation, attenuation coefficient, measures of agreement between the two methods, weighted kappa statistics and Bland-Altman plots were employed. SPSS 16 was used for statistical analysis.

Of the 120 subjects in the study, 71(59%) were males and 49(41%) were females with an overall mean age of 50.16±9.76 years. The correlation of estimated nutrient intake between the food frequency questionnaire and 24-hour dietary recall varied between 0.200 and 0.468, energy-adjusted regression was between 0.044 and 0.611 and attenuation coefficients of regression were between 0.339 and 0.658 for the selected macro and micro nutrients. Bland-Altman plots showed an acceptable agreement between the two methods. When nutrient intake was categorised in quartiles, proportions of the same or adjacent quartiles were 98.3%, 98.4%, 98.3%, 96.7% and 95% for energy, fat, protein, carbohydrates and fibre, respectively.

The first food frequency questionnaire developed in Turkish language was an adequate and valid tool to assess the nutritional habits of the local population.