Want to live longer?
Many studies look at the impact of just one lifestyle change on overall health, but researchers at Harvard University wanted to see the total impact of a healthy diet, regular exercise, a healthy weight and a lifetime without smoking.
Dr. Rob van Dam and a team from the Harvard School of Public Health and Brigham and Women's Hospital followed 80,000 nurses for more than two decades.
The women kept detailed records of their diet, physical activity, alcohol consumption, weight, smoking and disease history. Over the study period, 8,882 of the women died, including 1,790 from heart disease and 4,527 from cancer.
Some 28 percent of these deaths could have been avoided if the women had never smoked, the researchers said.
And 55 percent of the deaths could have been avoided if the women had never smoked and exercised regularly, eaten a healthy diet low in red meat and trans-fats and maintained a healthy weight, they said.
Smoking played the biggest role in causing premature death, and alcohol consumption played the smallest, they said.
They found women who drank up to one drink a day had a lower risk of heart disease than those who abstained from alcohol.
"These findings underscore the importance of intensifying both efforts to eradicate cigarette smoking and those aimed at improving diet and physical activity," van Dam and colleagues wrote in the British Medical Journal.