People who drink moderately, exercise, quit smoking and eat five servings of fruit and vegetables each day live on average 14 years longer than people who adopt none of these behaviours, researchers said on Tuesday.
Overwhelming evidence has shown that these things contribute to healthier and longer lives, but the new study actually quantified their combined impact, the British team said.
"These results may provide further support for the idea that even small differences in lifestyle may make a big difference to health in the population and encourage behaviour change," the researchers wrote in the journal PLoS Medicine.
Between 1993 and 1997 the researchers questioned 20,000 healthy British men and women about their lifestyles. They also tested every participant's blood to measure vitamin C intake, an indicator of how much fruit and vegetables people ate.
Then they assigned the participants - aged 45-79 - a score of between 0 and 4, giving one point for each of the healthy behaviours.
After allowing for age and other factors that could affect the likelihood of dying, the researchers determined people with a score of 0 were four times as likely to have died, particularly from cardiovascular disease.
The researchers, who tracked deaths among the participants until 2006, also said a person with a health score of 0 had the same risk of dying as someone with a health score of 4 who was 14 years older.
The lifestyle change with the biggest benefit was giving up smoking, which led to an 80 percent improvement in health, the study found. This was followed by eating fruits and vegetables.
Moderate drinking and keeping active brought the same benefits, Kay-Tee Khaw and colleagues at the University of Cambridge and the Medical Research Council said.
"Armed with this information, public-health officials should now be in a better position to encourage behaviour changes likely to improve the health of middle-aged and older people," the researchers wrote.
