Abstract
A dietary survey is used for defining and assessing the energy and nutrient intake. Most self-reporting methods rely on the portion size for recording a meal, and it is necessary to estimate the actual intake from the portion size. However, the definition of portion size in books and software for dietary surveys differs. There have been few studies on portion size, especially for vegetables, fruits, fish and meat. This study, therefore, investigates the difference in standard size of vegetables and fruits among prefectures and discuss the validity of using the portion size for a dietary survey. The types of size and names of size for each vegetable and fruit were numerous: eggplant had thirteen types of size and strawberry had twenty-eight types of size. In addition, there was weight difference in same size: the minimum was seven grams and the maximum was seventy four grams with the lower bounds of M size for strawberry. Our findings of a difference in the types of size suggest that it is necessary to improve the understanding and consistency of portion size between a participant and investigator, and among investigators when doing a dietary survey. It is vital to define which size and weight to use for portion size which can avoid underestimating or overestimating the actual intake.
