Traditional Japanese Diet Score - Association with Obesity, Incidence of Ischemic Heart Disease, and Healthy Life Expectancy in a Global Comparative Study

Objectives: We created a Traditional Japanese Diet Score (TJDS), and to clarify the relationship between TJDS and obesity, ischemic heart disease (IHD), and healthy life expectancy (HALE). Design Ecological study Setting Food (g/day/capita) and energy (kcal/day/capita) supply was determined using the Food and Agriculture Organization of the United Nations Statistics Division database. The sum of characteristic traditional Japanese foods (beneficial food components in the Japanese diet: rice, fish, soybeans, vegetables, eggs, and seaweeds; food components rarely used in the Japanese diet: wheat, milk, and red meat) was divided as tertiles (beneficial food components: -1, 0, 1; rarely used food components: 1, 0, -1). Obesity rate was determined using the World Health Organization database. Incidence of IHD, HALE and smoking rate were determined using the Global Burden of Diseases, Injuries, and Risk Factors Study 2015 database. Gross domestic product per capita, percentage of population > 65 years old, and health expenditure were determined using the World Bank database. Education years were obtained from the United Nations Educational, Scientific and Cultural Organization Institute for Statistics. Associations between TJDS and obesity, IHD and HALE were examined in 132 countries with a population of 1 million or greater using a general linear model controlled for co-variables. Results: TJDS was distributed from -6 to 7. TJDS was inversely correlated to obesity (beta +/- SE; -0.70 +/- 0.19, p<0.001), IHD (-19.4 +/- 4.3, p<0.001), and positively correlated to HALE (0.40 +/- 0.14, p<0.01). Conclusions TJDS is a good indicator of a healthy diet, and applies to preventing obesity, IHD and extending HALE.