Ueshima Hirotsugu
Department of Health Science, Shiga University of Medical Science, Shiga, Japan.
J Atheroscler Thromb. 2007 Dec;14(6):278-86. doi: 10.5551/jat.e529. Epub 2007 Dec 17.
Japan's age-adjusted rate for mortality from stroke increased after the Second World War until 1965 and then showed a significant decline until 1990; however, the age-adjusted rate for mortality from all heart disease and coronary heart disease (CHD) increased until 1970 and then declined slowly. A puzzling question is why the rate of mortality from CHD declined in spite of an increase in serum total cholesterol level following an increase in fat consumption. It was confirmed that CHD incidence was far lower in several Japanese populations compared to Western countries in the " Monitoring Trends and Determinants in Cardiovascular Disease " (MONICA) project; therefore, the lower CHD mortality in Japan stems from the lower CHD incidence. CHD risk factors based on epidemiologic cohort studies in Japan were no different from those of other industrialized countries: hypertension, hypercholesterolemia, smoking and diabetes mellitus (DM). So, how can we explain this phenomenon?There are three possible explanations. One is the decline in population blood pressure level and the prevalence of hypertension during the years 1965-1990; the second is the decline in smoking rate in men and women; the third is that the serum total cholesterol level for middle-aged and elderly populations remains 5-15 mg/dL lower than that of the US elderly counterpart, although men aged 40-49 in Japan and the US had similar serum total cholesterol levels. It was also noted that elderly people in Japan, as observed in the Seven Countries Study, had far lower serum total cholesterol levels in midlife, i.e., around 160 mg/dL in the 1960s. This was not the case for elderly in the US where a higher serum total cholesterol level was observed in midlife. In conclusion, the lower serum cholesterol level in the past of Japanese middle-aged and elderly people compared to Western counterparts helps to maintain the low CHD incidence and mortality supported by the declining trend in blood pressure level and smoking rate for both men and women.
二战后至1965年，日本经年龄调整的中风死亡率呈上升趋势，之后直至1990年则显著下降；然而，所有心脏病和冠心病（CHD）的经年龄调整死亡率在1970年前呈上升趋势，之后缓慢下降。一个令人困惑的问题是，尽管脂肪摄入量增加后血清总胆固醇水平有所上升，但冠心病死亡率为何下降。在“心血管疾病监测趋势和决定因素”（MONICA）项目中证实，与西方国家相比，几个日本人群的冠心病发病率要低得多；因此，日本较低的冠心病死亡率源于较低的冠心病发病率。基于日本流行病学队列研究的冠心病危险因素与其他工业化国家并无不同：高血压、高胆固醇血症、吸烟和糖尿病（DM）。那么，我们如何解释这一现象呢？有三种可能的解释。一是1965年至1990年期间人群血压水平和高血压患病率下降；二是男性和女性吸烟率下降；三是尽管日本和美国40至49岁男性的血清总胆固醇水平相似，但日本中老年人群的血清总胆固醇水平仍比美国老年人群低5至15毫克/分升。在七国研究中还注意到，日本老年人中年时的血清总胆固醇水平要低得多，即20世纪60年代约为160毫克/分升。美国老年人并非如此，他们中年时的血清总胆固醇水平较高。总之，与西方同龄人相比，日本中老年人过去较低的血清胆固醇水平有助于维持较低的冠心病发病率和死亡率，这得益于男性和女性血压水平和吸烟率的下降趋势。
