Invited commentary: 30-Year perspective on the seven countries study

In a 1986 article (Am J Epidemiol. 1986;124(6):903-915), Keys et al. described and discussed 15-year findings from 15 cohorts of the Seven Countries Study (SCS), the first systematic study of diet, risk characteristics, disease-specific death rates, and their ecologic and individual associations both among and within whole populations of working men in regions with contrasting traditional diets. The SCS findings included 30-fold cohort differences in rates of death from coronary heart disease and 3-fold differences in rates of death from all causes, along with strong ecologic associations among diet, risk factors, and disease rates. These results have motivated a generation of causal research conducted using bench, clinical, and population strategies. The study has contributed to survey methods, preventive practice, nutrition science, and policy on health, food and agriculture, and diet. The article is a succinct and accessible account by Ancel Keys, near the end of his long career, of the SCS design, conduct, and findings, with his discussion and interpretation of their importance. My commentary deals with the extent, validity, and historical meaning of SCS findings, as well as their influence and the influence of the 1986 article itself on epidemiologic thought and on public health. Students of epidemiology and of history should read this rich original source.