Long-term lifestyle and dietary habits in relation to cardiovascular mortality and life expectancy: a prospective cohort study

Introduction: In prospective cohort studies, information on lifestyle and dietary habits is generally only assessed at the baseline examination, assuming that these habits are relatively constant over the entire study period. Repeated measures can take into account changes in these habits, reduce measurement error due to a reduction in within-subject variation, and can give more insight into the etiology of diseases. The main objective of this thesis is to assess the relationships of recent and long-term exposure to known lifestyle and dietary risk factors with cardiovascular mortality and life expectancy. Methods: We used data from the Zutphen Study, a prospective cohort study among 1373 men born between 1900 and 1920. These men were examined repeatedly in seven examination rounds between 1960 and 2000. In addition to hazard ratios (HR), we presented some of our results in terms of differences in life expectancy at age 50. Main findings on lifestyle factors: We found that both the number of cigarettes smoked and smoking duration were strongly associated with mortality risk. Compared to never or long-term former smoking, cigarette smoking decreased life expectancy by about 7 years and exclusive cigar or pipe smoking decreased life expectancy by about 5 years. Stopping smoking cigarettes at age 50 increased life expectancy by 3.3 years. Furthermore, we observed that long-term light alcohol intake, i.e. <20 grams per day, compared to no alcohol intake, lowered cardiovascular (HR: 0.70 [95% confidence interval: 0.55 to 0.89]) and all-cause (HR: 0.75 [0.63 to 0.91]) mortality risk. Compared to men who do not consume alcohol, wine consumers had a 5 years longer life expectancy. Main findings on dietary factors: We observed that average trans unsaturated fatty acid intake decreased from 7 to about 1 percent of energy intake between 1960 and 2000 and that each additional 2 percent of long-term energy intake from trans unsaturated fatty acids was positively associated with sudden coronary death (HR: 1.62 [1.01 to 2.60]). In contrast, long-term fatty fish consumption was inversely associated with sudden coronary death (HR: 0.46 [0.27 to 0.78]). The strength of the association between long-term total fish consumption and coronary heart disease (CHD) death decreased from age 50 (HR: 0.32 [0.13 to 0.80]) until age 80 (HR: 1.34 [0.58 to 3.12]). We observed no clear dose-response relationship between the intake of the n-3 fatty acids EPA and DHA, and (sudden) coronary death. Finally, we found that each additional 10 grams of recent dietary fiber intake was associated with a lower risk of CHD (HR: 0.83 [0.70 to 0.98]) and all-cause (HR: 0.91 [0.82 to 1.00]) mortality. Conclusions: The studies described in this thesis emphasize the importance of lifestyle and diet for public health. Our results suggest that non-smoking and a low level of wine consumption decrease the risk of (cardiovascular) mortality and will increase life expectancy at age 50. The long-term consumption of fatty fish and the reduction in long-term trans unsaturated fatty acid intake may prevent sudden coronary deaths, and a higher recent dietary fiber intake may reduce both CHD and all-cause mortality risk.