Nonalcoholic Fatty Liver Disease in Japan Continue to Increase Even after the Launch of Specific Health Checkups.

Objective To examine the trends and relationships between nonalcoholic fatty liver disease (NAFLD) and hypertension, type 2 diabetes mellitus (T2DM), and dyslipidemia from fiscal year (FY) 2008, when specific health checkups (SHCs) were initiated in Japan, to FY 2019 and the relationship between NAFLD trends and dietary nutrition. Methods A total of 48,332 participants (25,121 men and 23,211 women) diagnosed with NAFLD who underwent health checkups, including ultrasonography, from FY 2008 to FY 2019 were included. A fatty liver was diagnosed using ultrasonography. The dietary nutrient intake status was based on data from the National Health and Nutrition Survey, Japan. Results Over 12 years, NAFLD prevalence increased from 26.9% to 43.1% in men (p<0.0001) and from 9.9% to 17.9% in women (p<0.0001) in all body mass index (BMI) groups except for obese II (according to the World Health Organization Asia-Pacific criteria) in men and underweight in women and almost all age groups. T2DM prevalence increased in men (from 9.0% to 10.7%, p=0.0234), and obesity and higher waist circumference rates increased in women (from 16.0% to 18.0%, p=0.0059 and from 8.1% to 10%, respectively, p=0.0006). The dietary nutrient intake increased with regard to the total fat, fat/energy ratio, saturated fatty acids, monounsaturated fatty acids, and n6/n3 fatty acid ratio in both men and women, and these nutrient trends were correlated with NAFLD prevalence (all p≤0.0005). Conclusion In Japan, NAFLD increased in both men and women regardless of the BMI and age, even after starting SHCs. An unbalanced fat intake may be one of the major reasons for this increase.