Achievements and Challenges of Social Epidemiology Research Aiming to Reduce Health Inequality: A Revised English Version of Japanese in the Journal of the Japan Medical Association 2020;149(9):1626-30.

Health inequalities are defined as "gaps in health status between groups, which are created by differences in community or socioeconomic status." In response to the General Assembly Resolution (2009) of the World Health Organization, the World Medical Association issued a statement in the same year, and the Japanese health policy "Health Japan 21 (second term)" indicated a "reduction of health inequalities" as the basic direction. In 2000, we described the presence of health inequalities in Japan, which was regarded as a relatively egalitarian country. This was the starting point of the Japan Gerontological Evaluation Study. It was developed into large longitudinal studies that reveal the significance of "social determinants of health" that cause health inequalities. We verified the feasibility and effects of healthy aging policies by fostering social capital through community intervention studies. These findings and knowledge have been translated into municipal and central government policies. Here we review what has been achieved and the remaining challenges in more than 20 years of social epidemiological research.