A data-based approach for designing a semiquantitative food frequency questionnaire for a population-based prospective study in Japan.

A self-administered food frequency questionnaire (FFQ) has been used commonly in epidemiologic studies of diet and chronic diseases. The analysis of dietary data in the target population is useful for designing a new questionnaire. The authors studied the major food sources of nutrient intakes in the Japanese population in order to develop a FFQ for a population-based prospective study. Subjects were 180 men aged 40-49 years and their 155 spouses who were sampled from four Public Health Center districts. Weighed food records over three consecutive weekdays were collected during the winters of 1989-1991. All foods reported were grouped into 154 items, and the percent contribution of each food to the total population intake of 15 nutrients was computed. Based on these data, a FFQ with 138 items was developed. The food list covered well the population intake of most nutrients (median = 83%, range = 55-91%), except for lipid (70%) and sodium (55%). The questionnaire was applied to the prospective study conducted in the same areas where the dietary data were collected, and an investigation to assess its reproducibility and validity is currently underway.