This study was carried out to examine first, the validity of a new dietary assessment method, a handheld personal digital assistant with camera and mobile phone card (Wellnavi), in comparison with a weighed diet record as a reference method and second, the relation between obesity and underreporting in the Wellnavi method in 27 men and 48 women volunteers aged 30-67 y from the general population. On the validity, there were significant correlations (0.32-0.75) between the daily nutrient intakes measured by the Wellnavi method and the weighed diet record method in all the subjects except for some nutrients such as iron, magnesium and vitamin E. Results similar to those from the group of all the subjects were obtained in the men's group and the women's group. In all the subjects and the men's group and the women's group, the differences in the daily nutrient intakes between the two dietary assessment methods were statistically significant. However, good agreement of the differences between the two dietary assessment methods for many daily nutrient intakes was obtained in the nonobese men. The nutrient intakes estimated by the Wellnavi method in all the subjects and the men's group and the women's group were significantly lower than those values estimated by the weighed diet record method except for some nutrients such as sodium, iron and fat-soluble vitamins. With respect to the relation between obesity and underreporting, the obesity in women was not a factor of underreporting in the Wellnavi method, but the presence of this relation was undeniable in the obese men. The reason why the values of daily nutrient intakes in the Wellnavi method were lower than those estimated by the weighed diet record method seemed to be the low quality of the digital photo of the Wellnavi instrument. By improving the digital photo quality of this instrument, the Wellnavi method could become a useful new dietary assessment method to get accurate dietary information from people of a wide range of age and occupation, and a wide variety of physical situations of subjects from the general population.
2007 by the Center for Academic Publications Japan