The aim of the present study is to investigate the validity of a new method to estimate the food intake of individual subjects by a household-based dietary survey. The new method is based on the combination of household-based food weighing and approxi-mating the proportions by which family members shared each dish or food in the house-hold, which has been one of the components of the National Nutrition Survey, Japan, since 1995. We analyzed two sets of data from 64 volunteers (female students taking a dietitian course and their mothers) in 32 households by the approximated proportion method (method A) and the individual-based food weighing method (B) as a reference measurement. Energy and macronutrient intake by individual subjects estimated by method A was highly correlated to the corresponding values by method B (Pearson's correlation coefficients; r=0.90-0, 92). Average energy intake was likely to be underestimated by method A com-pared with method B, being lower by 94 kcal (6.2% of the reference value in method B), at least in the young and middle-aged female adults that were the subjects of this study when intake of boiled rice was separately analyzed, underestimation of energy intake by method A was 44 kcal, which contributed to approximately 50% of the total magnitude of the under-estimation. The procedure manual for the National Nutrition Survey requests the partici-pants to individually weigh the amount of boiled rice taken by family members in the house-hold. However, this procedure is not observed in many actual settings. Therefore, following this procedure would be an effective measure to improve the accuracy of the dietary data.
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