Abstract
The National Nutrition Survey is a unique survey that provides nationwide information on nutrient intake in Japan. Descriptive statistical data of nutrient intake, which has not been described in annual reports, are summarized in this report. A dataset from the National Nutrition Survey between 1995 and 1999 was used for analyses. The distribution of vitamin A intake had an extremely long righth-and tail and the difference between mean and median was very large. The results alert us to understand and use statistics properly when one summarizes the data. Means and medians of each nutrient intake except vitamin C were higher in men than in women, however, means and medians of nutrient density (per 1, 000 kcal energy intake) for all nutrients were higher in women than in men. Fat intake was the highest in individuals in their 20s and gradually declined in older age groups. Most of other forms of nutrient intake were the highest in individuals in their 50s or 60s and declined in older age groups. However, a declining trend with aging was not observed in the nutrient density of all nutrients except fat. These statistical data would support better interpretation of the survey data. Furthermore, some methodological limitations in the dietary assessment of the present survey, including the possibility of overestimating nutrient intake by not taking nutrient loss during the cooking process in households into account, were discussed. It is important to use and interpret the survey data under careful consideration on such methodological limitations.
