Life expectancy is influenced not only by the traditional lifestyle-related risk factors but also by factors related to a person's quality of life, such as heavy stress. The biggest causes for shortened life expectancy for 30-year-old men are smoking and diabetes. Smoking takes 6.6 years and diabetes 6.5 years out of their life expectancy. Being under heavy stress shortens their life expectancy by 2.8 years.
These results are based on a study in which researchers from the Finnish Institute for Health and Welfare calculated the effects of multiple risk factors, including lifestyle-related ones, to the life expectancy of men and women.
The study also revealed that a lack of exercise strongly reduced the life expectancy of 30-year-old men - by 2.4 years. On the other hand, things such as the consumption of plenty of fruits and vegetables could increase life expectancy: eating fruit by 1.4 years and eating vegetables by 0.9 years.
The same factors impacted the life expectancy of both men and women. For 30-year-old women, e.g. smoking shortened the life expectancy by 5.5 years, diabetes by 5.3 years, and heavy stress by 2.3 years.
The effects to the life expectancy of older people were similar but smaller than in younger age groups.
The golden middle seemed to have the most positive effect in some factors related to lifestyle. The experience of stress increased the life expectancy if the person felt the amount of stress they had was approximately the same as what other people typically experienced. Having more or less stress than that, on the other hand, reduced their life expectancy.
A new calculation method in use for a large group of risk factors for the first time
The study was based on data collected from men and women aged 25 to 74 in the Finnish National FINRISK Study 1987-2007 through questionnaires and measurements. The rate of mortality was followed until the end of 2014.
The researchers calculated the life expectancies by changing the values of each risk factor at a time and keeping the values of other factors constant. Only the BMI, blood pressure, and cholesterol levels were allowed to be changed when the values related to lifestyle factors were changed.
Before, life expectancy has usually been assessed based on only a few sociodemographic background factor groups, such as age, sex, and education. In this study, we wanted to assess the impact of several different factors to a person's life expectancy, so we could compare their effects."
Tommi Härkänen, Research Manager
Differences between the life expectancies of men and women largely due to risk factors that can be changed
"What was interesting about the study was how small the difference in the life expectancy of 30-year men and women was based on the same risk factor values - only 1.6 years. According to the statistics from Statistics Finland, the difference between the sexes has been over five years for all 30-year-olds, which comes down to women having healthier lifestyles than men," says Research Professor Seppo Koskinen.
In this study, the differences in the life expectancies of people with different levels of education were fairly small when the other risk factor values were the same. However, earlier studies have discovered large differences between the life expectancies of groups of people with different levels of education.
The lifestyle choices that increase mortality, such as smoking, heavy alcohol use, unhealthy diet, and lack of exercise, are most common in the population groups whose social position is the weakest.
The life expectancy of the whole population could be improved significantly through helping men and people with a lower level of education, in particular, make better lifestyle choices.
Härkänen, T., et al. (2020) Estimating expected life-years and risk factor associations with mortality in Finland: cohort study. BMJ Open. doi.org/10.1136/bmjopen-2019-033741.