Japanese Diet Indices and Nutrient Density in US Adults: A Cross-Sectional Analysis with NHANES Data

Background: Previous studies have shown that Japanese dietary patterns are associated with high nutrient density. However, these studies were limited to the Japanese population. We examined this association in the US population. Methods: A cross-sectional analysis was conducted using data from the National Health and Nutrition Examination Survey (NHANES) 2017-2018. We included 3138 people aged 20-79 years. Food and nutrient intake data were based on the 24 h recall method. Three Japanese diet indices were used: (1) Japanese Diet Index (JDI, based on 9 food items), (2) modified JDI (mJDI, based on 12 food items), and (3) weighted JDI (wJDI, selected and weighted from mJDI food items). The nutrient density (ND) score was calculated based on the Nutrient-Rich Food Index 9.3. Spearman's rank correlation coefficients were calculated. Results: The correlation coefficients with the ND score were 0.24 (p < 0.001) for the JDI and 0.38 (p < 0.001) for the mJDI. The correlation coefficient between the wJDI and ND score was 0.48 (p < 0.001). The three Japanese diet indices were correlated with the ND score in all racial groups (p < 0.001). Conclusions: Even among the US population, higher degrees of Japanese diet defined by the JDI or mJDI were associated with higher nutrient density.