A Validation Study on a Method to Estimate Nutrient Intake by Family Members through a Household-based Food-weighing Survey.

Abstract

SummaryThe 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 94kcal (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 44kcal, 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 . Key Words dietary survey, food weighing method , individual-based survey, validation, biasThe dietary survey is a core component of nation wide nutrition monitoring (1), including the National Nutrition Survey, Japan (NNS-J), The NNS-J was initi ated in 1946 with the main purpose of obtaining basic information for emergency food supplies from other countries (2), Thus, household-based food consumption data had been conventionally collected from the stand point of food security. The aim of the survey, however, has shifted from food supply issues to chronic disease prevention, and individual-based dietary data have be come essential to clarify diet-disease relationships .A new method (hereinafter called the approximated proportion method) to estimate the food intake of individ ual subjects in a household has been used in the NNS-J since 1995. This method is based on a combination of household-based food weighing and an approximation of proportions by which family members shared each dish or kind of food in the household (3 , 4) (Fig. 1). This hybrid method was adopted by the NNS-J because it was * To whom correspond ence should be addressed. E-mail: nobuoyos@nih.go.jp expected to allow comparisons with dietary data that had been conventionally collected for more than 50 years by the household-based food weighing method.The aim of the study is to investigate the valid...

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