Critical examination of reported energy intake in published dietary studies of Japanese subjects using the Goldberg cut-off.

Although it is now generally acknowledged in Western countries that mismeasurement (under- and overestimation) of dietary intake is a serious problem in studies on diet and health, the validity of dietary assessment methods in Japan has seldom been externally evaluated with objective measures. This study used the Goldberg cut-off to examine whether the energy intake in Japan could be regarded as a measure of habitual energy intake at the group level. Examined here were six published dietary studies in Japan providing 14 subgroups when divided by sex and dietary assessment method. Reported energy intake was expressed as a multiple of basal metabolic rate estimated using equations (EI/BMR). EI/BMR was compared with the subgroup-specific cut-off values representing the lowest and highest values of EI/BMR that could reflect the habitual energy expenditure. Mean EI/BMR was 1.49 (SD=0.09), which was lower than an expected requirement of 1.55. When all 14 subgroups were combined, seven subgroups (50%) had an EI/BMR less than the subgroup-specific lower cut-off value, and one (7%) had the ratio greater than the upper value. The percentages of subgroups having the ratio less than the lower value and greater than the upper value ranged from 43 to 57% and from 0 to 14%, respectively, when subgroups of women (n=8), men (n=6), diet record (n=7), and questionnaire method (n=7) were evaluated separately. These findings suggest that responsible investigators in Japan should critically examine dietary intake data in any study of diet and health.