The Healthy Diet Indicator (HDI), which is based on adherence to World Health Organization's (WHO) nutrition guidelines, is used worldwide. In 2015, the WHO updated the Fact Sheet for their recommended healthy diet. We investigated diet quality assessed by the updated HDI (HDI-2015) and factors related to adherence to this diet in a Japanese population. We conducted a cross-sectional study of 1370 participants from 8 workplaces, 1 college, and 2 communities. All participants completed a brief-type self-administered diet history questionnaire. The HDI-2015 assesses 7 components: fruits and vegetables, total fat, saturated fatty acid, polyunsaturated fatty acid, free sugar, dietary fiber, and potassium. Only 6.6% of subjects demonstrated high adherence to HDI-2015 (met ≥6 components), whereas 52.0% demonstrated moderate adherence (4-5 components), and 41.4% demonstrated low adherence (0-3 components). Male sex, older age, and regular physical activity were associated with higher adherence. The contemporary Japanese population has an overall low diet quality as evaluated by the updated HDI score. Improving adherence to healthier dietary patterns may promote better health in Japan.
Keywords: Diet quality; Healthy Diet Indicator; Japanese; World Health Organization.