A validation study on a method to estimate nutrient intake by family members through a household-based food-weighing survey

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 di etary survey. The new method is based on the combination of household-based food weighing and approximating the proportions by which family members sh ared each dish or food ill the household, which has been one of the compone nts of the National Nutrition Survey, Japan, since 1995. We analyzed two se ts of data from 64 volunteers (female students taking a dietitian course an d their mothers) in 32 households by the approximated proportion method (me thod A) and the individual-based food weighing method (B) as a reference me asurement. 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 wa s likely to be underestimated by method A compared with method B, being low er by 94 kcal (6.2% of the reference value in method B). at least in the yo ung and middle-aged female adults that were the subjects of this study. Whe n intake of boiled rice was separately analyzed, underestimation of energy intake by method A was 44 kcal, which contributed to approximately 50% of t he total magnitude of the underestimation. The procedure manual for the Nat ional Nutrition Survey requests the participants to individually weigh the amount of boiled rice taken by family members in the household. However, th is 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.