Food and nutrient intakes assessed with dietary records for the validation study of a self-administered food frequency questionnaire in JPHC Study Cohort I.

We present here the survey methods and basic results of dietary records which were used as reference values in the present validation study of a self-administered food frequency questionnaire (FFQ) for the 5-year follow-up survey of the JPHC study. A semi-weighed dietary record was kept for four seven consecutive days in each of the four seasons in 3 areas, i.e., Iwate, Akita, and Nagano, and for seven consecutive days in both winter and summer in Okinawa. The mean intakes were significantly different between areas for some nutrients and food groups. A significant seasonal difference in the mean intakes was also observed in some nutrients such as carotene and vitamin C, and in some food groups such as potatoes, vegetables, and fruits in both sexes, and alcoholic beverages in men and milks in women (p<0.001).