First, I would like to express my sincere appreciation to the study participants, co-investigators and members of the board for their wonderful cooperation. Because our population-based epidemiological study requires a mass of people, we could not have achieved our goal without the people in Seattle and Japan who unselfishly spent their time to go through screening tests and the questionnaire.The Japanese are often assumed to be a healthier population generally than are Americans. The image of the Japanese as a fish-, vegetable-, and rice-eating people who are less obese than are Americans may have contributed to this assumption. Life expectancies for Japanese and American men, 76 and 72 years, respectively, and for Japanese and American women, 83 and 79 years, respectively, support this perception.Detailed comparisons of cause-specific death rates reveal that the relative health status of the two peoples is not so simple. For example, consider the death rates for specific causes of death in Japan versus the United States (Table 1). Why do such differences in mortality exist between the two nations? Are the differences caused by race (genetics) or the environment?

Table1. Comparison of mortality by selected causes between the United States and Japan.