development and validation of a dish-based iranian food frequency questionnaire: a protocol study

Background: the relation between long-term dietary intake and diseases is well known. there are several methods to determine long-term dietary intake. the food frequency questionnaire (ffq) is used in studies to assess habitual dietary intake over a long term period. dietary intake varies according to cultural differences, so an ffq must be designed and validated for the target population. this protocol study aims to explain the development and validation of a semi-quantitative ffq for the iranian population that includes mixed dishes and single food items. methods: the initial list of food items were extracted from interviews and expert opinion. an expert panel of ten nutritionists calculated the content validity ratio (cvr) and content validity index (cvi) of food items to finalize the ffq. one hundred twenty eligible participants were included in the study. they completed the ffq two times, with a ten month interval. they recorded their food intake for three days in the 2nd and 10th months of the study. in the 4th and 10th months, serum retinol and alpha-tocopherol, and 24-hour urinary potassium and nitrogen were measured. result: covering typical iranian mixed dishes is the main advantage of this study. given that the questionnaire is valid and reproducible, it can be used in epidemiologic studies. conclusion: the current study developed a dish-based iranian ffq based on mixed food.