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BackgroundA previous study reported the development a 75-item food frequency questionnaire for Japanese children (CFFQ). The first aim was to examine the reproducibility and validity of the CFFQ in order to assess dietary intake among two groups; 3-11 year old children (YC group) and 12-16 year old children (AD group). The second aim was to use the CFFQ and the FFQ for adults (AFFQ), and to determine which was better suited for assessing the intake of children in each group.MethodsA total of the 103 children participated in this study. The interval between the first CFFQ and AFFQ and the second CFFQ and AFFQ was one month. Four weighted dietary records (WDRs) were conducted once a week. Pearson's correlation coefficients between the first and second FFQs were calculated to test the reproducibility of each FFQ. Pearson's correlation coefficients between WDRs and the second FFQ were calculated for the unadjusted value and sex-, age-, and energy-adjusted values to determine the validity of each FFQ.ResultsThe final number of subjects participating in the analysis was 89. The median correlation coefficients between the first and second CFFQs and AFFQs were 0.76 and 0.73, respectively. There was some over/underestimation of nutrients in the CFFQ of the YC group and in the AFFQ of the AD group. The medians of the sex-, age-, and energy-adjusted correlation coefficients were not different between the YC and AD groups for each FFQ. The correlation coefficient in sex-, age-, and energy-adjusted value revealed that the largest number of subject with high (0.50 or more) value was obtained by the CFFQ in the YC group.ConclusionsThis study indicated that the CFFQ might be a useful tool for assessing habitual dietary intake of children in the YC group. Although the CFFQ agreed moderately with habitual intake, it was found to underestimate intake in theAD group. However, for the AFFQ, the ability to rank habitual intake was low. Therefore, it is necessary to develop a new FFQ or modify an existing FFQ to accurately assess the habitual diet of children in the AD group.

Monitoring nutritional status of the population is essential in the development and evaluation of national or local health policies. In this study, we aimed to demonstrate analysis on the trends in dietary intake of energy and macronutrients, as well as Na, in Japanese population using the data of series of cross-sectional national surveys - the National Nutrition Survey (NNS) and the National Health Nutrition Survey (NHNS) - during the period from 1995 to 2016. The NNS and NHNS participants aged 20-79 years were included in the analysis. Dietary intake was estimated using 1-d household-based dietary record. The trend in total energy intake, energy intake from macronutrients (fat and protein), Na intake and energy-adjusted Na intake were analysed using regression models adjusted to 2010 age distribution and anthropometry status. A total of 94 270 men and 107 890 women were included the analysis. Total energy intake showed a decreasing trend in both men and women. Similarly, energy intake from protein decreased, but energy intake (%) from fat increased in both sexes. Energy-adjusted Na intake showed a decreasing trend in both men and women. This study identified the decrease in total energy intake and energy intake from protein, whereas there were inverse trends in energy intake from fat among Japanese adults. Continued monitoring of trends in dietary intake will be needed, and there should be efforts to increase the accuracy of current survey procedures.

BackgroundFood frequency questionnaires (FFQ) are used for epidemiological studies. Because of the wide variations in dietary habits within different populations, a FFQ must be developed to suit the specific group. To date, no FFQ has been developed for Japanese children. In this study, we developed a FFQ to assess the regular dietary intake of Japanese children. The FFQ included questions regarding both individual food items and mixed dishes.MethodsChildren (3-11 years of age, n = 621) were recruited as subjects. Their parents or guardians completed a weighed dietary record (WDR) for each subject in one day. We defined FOOD to be not only as a single food item but also as a mixed dish. The dieticians conceptually grouped similar FOODs as FOOD types. We used a contribution analysis and a multiple regression analysis to select FOOD types.ResultsWe obtained a total of 586 children's dietary data (297 boys and 289 girls). In addition, we obtained 1,043 FOODs. Dieticians grouped into similar FOODs, yielding 275 FOOD types. A total of 115 FOOD types were chosen using a contribution analysis and a multiple regression analysis, then we excluded overlapping items. FOOD types that were eaten by fewer than 15 subjects were excluded; 74 FOOD types remained. We also added liver-based dishes that provided a high amount of retinol. A total of 75 FOOD types were finally determined for the FFQ. The frequency response formats were classified into four type categories: seven, eight, nine and eleven, according to the general intake frequency of each FOOD type. Information on portion size was obtained from the photographs of each listed FOOD type in real scale size, which was the average amount of the children's portion sizes.ConclusionsUsing both a contribution analysis and a multiple regression analysis, we developed a 75-food item questionnaire from the study involving 586 children. The next step will involve the verification of FFQ reproducibility and validity.