ABSTRACT
BACKGROUND: Underreporting in self-reported dietary survey is a potential source of bias in nutritional epidemiology. We assessed if dietary underreporting existed in the 2001 Korean National Health and Nutrition Survey (KNHANS) and evaluated the health related factors and nutrients associated with dietary underreporting. METHODS: The subjects were 2,552 men and 3,335 women, 18 years of age or older, with a complete 24 hour recall and physical examination data including height and weight. Basal metabolic rate (BMR) was calculated from weight and height using WHO equations. Questionnaire to assess daily physical activity and regular exercise was done. EI/BMR ratio was used to evaluate dietary underreporting. RESULTS: The mean EI/BMR ratio of Korean men and women were 1.43+/-0.56 and 1.41+/-0.57, respectively. Among the total, 20.6% of men and 22.8% of women reported their energy intake lower than their BMR. Age was negatively related with EI/BMR ratio only in women (P<0.001). Body mass index, education level, and household income were negatively and daily physical activity was positively associated with the EI/BMR ratio in both sexes. Lower EI/BMR ratio was significantly associated with lower reported fat energy density (% of energy intake) and higher reported carbohydrate and protein energy densities. The EI/BMR ratio was related negatively with nutrient energy densities of Vitamin C, Calcium, and Iron. CONCLUSION: We could confirm selective dietary underreporting in the 2001 KNHNS. Caution should be paid on the interpretation of the nutrition survey data and efforts should be exercised to reduce dietary underreporting at data collection stages.