Calibration of a food frequency questionnaire in Koreans

The current trend of changes in nutrient intakes may have some relationship with the increase in the occurrence of degenerative diseases in the Korean population. To date, a calibrated food frequency questionnaire (FFQ) has not been developed that can be further used for large-scale epidemiological research in Koreans aged 40 and older. This study was undertaken to develop and calibrate an FFQ in Koreans. A total of 144 Koreans aged 40 years and above participated in the first phase, which was conducted using the three-day dietary record method. One hundred and thirty-eight of those who completed the first phase were then interviewed to test FFQ against dietary records as a reference. The mean absolute nutrient intakes estimated by the dietary records were statistically compared with those estimated by the FFQ using paired t-tests. The mean values from the FFQ differed at most by 14% from those of the dietary records for all nutrients with the exception of vitamin A. Spearman rank-order correlation coefficients and cross-classification were also calculated. The energy-adjusted and corrected correlations for attenuation varied from 0.36 to 0.82. The degree of good agreement by cross-classification between the dietary records and the FFQ ranged from 67% to 90%. The newly developed FFQ can be used as a dietary assessment tool to measure usual nutritional status of Koreans aged 40 years and older. Furthermore, this study demonstrates that the FFQ also provides a more labour-efficient tool that is easier to use than any of the commonly used methods for large-scale epidemiological studies of the relationships between nutrition and diseases in Koreans.