Background: The Seven Countries Study has shown that population mortality rates for various chronic diseases are related to diet and smoking. This paper addresses the associations between diet, smoking and 25-year all-cause mortality.
Methods: Baseline surveys were carried out between 1958 and 1964 on 12,763 middle-aged men constituting 16 cohorts in seven countries. In 1987/88 equivalent food composites representing the average food intake of each cohort at baseline were collected and chemically analysed in one central laboratory. During 25 years of follow-up 5973 men died and age-adjusted population mortality rates were calculated for each cohort.
Results: Multivariate linear regression analyses showed that the population intake of saturated fat and the prevalence of smoking were positively associated with population all-cause mortality rates. Population vitamin C intake was inversely associated with all-cause mortality. It was calculated that a reduction in saturated fat intake of 5% of energy, a 20 mg/d increase in vitamin C and a 10% decrease in the prevalence of smokers may decrease the 25-year all-cause population mortality rate by 12.4% (95% CI: 5.6, 19.4%) at an average population all-cause mortality rate of 45%.
Conclusion: At the population level saturated fat, vitamin C and cigarette smoking are important determinants of all-cause mortality.