The social gradient in life expectancy: the contrary case of Okinawa in Japan

This paper examines the social gradient theory of health and life expectancy presented by Evans and his colleagues [Evans, R.G., Barer, M.L. and Marmor, T.R. (Eds.), 1994. Why are some People Healthy and others not? The Determinants of Health of Populations. Aldine de Gruyter, New York]. They maintain that social hierarchy is the determining factor in the health of large populations largely because it promotes differences in stress or the ability to cope with stress. For example, as Japan has risen to the top ranks of the economic hierarchy of nations in the late 20th century, Japanese life expectancy improved dramatically. Evans [Evans, R.G., 1994. Introduction. In: Evans, R., Barer, M., Marmor T. (Eds.), Why are some People Healthy and others not? The Determinants of Health of Populations. Aldine de Gruyter, New York, pp. 3–26.] notes that something lies behind this rapid increase in longevity and the major change was the hierarchical position of Japan relative to the rest of the world. However, we reviewed life expectancy data within Japan and found that Okinawans traditionally rank at the top in health and life expectancy and at the bottom in socioeconomic indicators. We find that the social gradient thesis does not apply in Japan and suggest that what is more important for health are health lifestyles, especially diet and social support. More research is needed to assess the validity of the social gradient thesis if it is to be used on a cross-national basis.