Rich and slim, but relatively short Explaining the halt in the secular trend in Japan

Abstract

An almost complete halt in the secular trend in stature at a relatively low level is observed in Japan since the late 1980s with average height of around 171 cm for males and 158 cm for females at age 18. Unidentified characteristics in the Japanese genetic pool or in the nutritional intake do not provide a convincing explanation. Japan is unique among OECD countries in combining contrasted health outcomes: a stagnation of height suggests a decline in biological well-being, but this picture is not consistent with high life expectancy and extremely low prevalence of infant mortality, overweight/obesity, and other pathologies. Individual data that could allow investigating the influence of socio-economic and other environmental conditions are unavailable. As a second best, we take advantage of the regional variance in average height and other indicators across the 47 Japanese prefectures and use data covering the period 1950-2005. A positive and significant influence of income and housing conditions on height is identified but the effect is fading. Caloric restraint of pregnant women, and the decrease in sleeping time observed since the 1980s appear as possible explanatory variables of the halt in the secular trend and a symptom of a decline in well-being. Public health policy implications are considered.height, income, housing, sleep, sexual dimorphism, Japan