Objectives: To examine the validity and reproducibility of a self-administered foodfrequency questionnaire (FFQ) used for two cohort studies in Japan. Design: Cross-sectional study. Setting: Two rural towns in the Miyagi Prefecture, in north-eastern Japan. Subjects: Fifty-five men and 58 women. Results: A 40-item FFQ was administered twice, 1 year apart. In the mean time, four 3-day diet records (DRs) were collected in four seasons within the year. We calculated daily consumption of total energy and 15 nutrients, 40 food items and nine food groups from the FFQs and the DRs. We computed Spearman correlation coefficients between the FFQs and the DRs. With adjustment for age, total energy and deattenuation for measurement error with the DRs, the correlation coefficients for nutrient intakes ranged from 0.25 to 0.58 in men and from 0.30 to 0.69 in women, with median of 0.43 and 0.43, respectively. Median (range) of the correlation coefficients was 0.35 (2 0.30 to 0.72) in men and 0.34 (2 0.06 to 0.75) in women for food items and 0.60 (20.10 to 0.76) and 0.51 (0.28 -0.70) for food groups, respectively. Median (range) of the correlation coefficients for the two FFQs administered 1 year apart was 0.49 (0.31-0.71) in men and 0.50 (0.40-0.64) in women for nutrients, 0.43 (0.14 -0.76) and 0.45 (0.06-0.74) respectively for food items, and 0.50 (0.30 -0.70) and 0.57 (0.39-0.66) respectively for food groups. Relatively higher agreement percentages for intakes of nutrients and food groups with high validity were obtained together with lower complete disagreement percentages. Conclusions: The FFQ has a high reproducibility and a reasonably good validity, and is useful in assessing the usual intakes of nutrients, foods and food groups among a rural Japanese population.
Objectives: To determine the relative contribution of intra-and inter-individual variation in the consumption of foods and nutrients. Design: Cross-sectional study. Setting: Two rural towns in the Miyagi Prefecture, a northeastern part of Japan. Subjects: Fifty-nine men and sixty women. Methods: Four 3-d food records were collected in four seasons within a year. The total variance in the consumption of 15 nutrient variables and 16 food groups was partitioned by analysis of variance into its interand intra-individual components, separately for men and women. Results: The ratio of the intra-to inter-individual variance was larger than unity in 87% (13a15) of the nutrients in men and 100% (15a15) in women. The ratio was largest for retinol (52.9 in men and I in women) and smallest for carbohydrates (0.8 in men and 1.5 in women). The ratio was larger than unity in 88% (14a16) of the food groups in men and 94% (15a16) in women, which was smallest for cereals (0.6 in men and 0.9 in women).
Conclusions:The results were consistent with previous western studies in that intra-individual variation was generally larger than inter-individual variation for the consumption of both foods and nutrients.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.