A killer quartet of unhealthy behaviours - smoking, drinking, poor diet and inactivity - can slash average life span by 12 years, but lifestyle changes can help stem the damage, researchers have discovered.
Individuals who engaged in all four high-risk behaviors suffered three times the death rate for cancer and heart disease, and four times the death rate from other causes, as people who engaged in none of the behaviours, according to research published in Monday's issue of Archives of Internal Medicine.
Researchers studied 4,886 people 18 or older in 1984 and 1985, and assigned a health behaviour score for each person based on their participation in the bad behaviors: a score of four for someone who engaged in all four unhealthy behaviors, and zero for people who did none of them.
In essence, the higher the score, the shorter the average lifespan, according to the authors.
Over an average 20 years of follow-up, 1,080 of the participants died - 431 from cardiovascular disease, 318 from cancer and 331 from other causes. Compared with participants who had none of the poor health behaviours, the risk of death increased with each additional poor behaviour, the authors wrote.
A person with a score of four has "an overall death risk equivalent to being 12 years older" than someone who engages in none of the poor behaviors, the study said.
"To fully understand the public health impact of these behaviours, it is necessary to examine both their individual and combined impact on health outcomes," said Elisabeth Kvaavik of the University of Oslo, one of the study's authors.
The behaviors were determined as: smoking; eating fruits and vegetables less than three times per day; engaging in less than two hours of physical activity per week; and drinking more than 4.2 ounces (0.12 liters) of alcohol per week for women, and 6.3 ounces for men.
Cutting back or ending these behaviours could add years to one's life, the study said.
"Modest but achievable adjustments to lifestyle behaviours are likely to have a considerable impact at both the individual and population level," the authors said.
"Developing more efficacious methods by which to promote healthy diets and lifestyles across the population should be an important priority of public health policy."