To get an extra 14 years of life, don't smoke, eat lots of fruits and vegetables, exercise regularly and drink alcohol in moderation.

That is according to a study published Monday in the Public Library of Science Medicine journal.

After tracking more than 20,000 people aged 45 to 79 years in the United Kingdom from about 1993 to 2006, Kay-Tee Khaw of the University of Cambridge and colleagues found that people who adopted these four healthy habits lived an average of 14 years longer than those who didn't.

"We've known for a long time that these behaviors are good things to do, but we've never seen these additive benefits before," said Susan Jebb, head of Nutrition and Health at Britain's Medical Research Council. Jebb was not involved in the study.

"Just doing one of these behaviors helps, but every step you make to improve your health seems to have an added benefit," she said. The benefits were also seen regardless of whether or not people were fat and what social class they came from.

Study participants scored a point each for not smoking, regular physical activity, eating five servings of fruits and vegetables a day and moderate alcohol intake. People who scored four were four times less likely to die than those who scored zero. Researchers tracked deaths from all causes, including cardiovascular disease, cancer and respiratory diseases.

Participants filled in a health questionnaire and nurses conducted a medical exam at a clinic. The study was largely paid for by the Medical Research Council and Cancer Research United Kingdom.

Khaw said that the study should convince people that improving their health does not always require extreme changes to their lifestyles. "We didn't ask these people to do anything exceptional," Khaw said. We measured normal behaviors that were entirely feasible within people's normal, everyday lives."

Public health experts said they hoped the study would inspire governments to introduce policies helping people to adopt these changes.

"This research is an important piece of work which emphasizes how modifying just a few risk factors can add years to your life," said Dr. Tim Armstrong, a physical activity expert at the World Health Organization.

But because the study only observed people rather than testing specific changes, experts said that it would be impossible to conclude that people who suddenly adopted these healthy behaviors would automatically gain 14 years.

"We can't say that any one person could gain 14 years by doing these things," said Dr. Tim Armstrong, a physical activity expert at the World Health Organization. "The 14 years is an average across the population of what's theoretically possible."

Experts are also unsure if these new findings will actually improve the public's health.

"What stops people from changing their behavior is not a lack of knowledge," Jebb said.

"Most people know that things like a good diet matter and that smoking is not good for you," she said. "We need to work on providing people with much more practical support to help them change."