LONDON -- 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's the finding of a study that tracked about 20,000 people in the United Kingdom.

Kay-Tee Khaw of the University of Cambridge and colleagues calculated 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, which helped pay for the study.

"Just doing one of these behaviors helps, but every step you make to improve your health seems to have an added benefit," said Jebb, who was not involved in the study.

The benefits were also seen regardless of whether or not people were fat and what social class they came from. The findings were published online last week in the Public Library of Science Medicine journal.

The study included healthy adults aged 45 to 79. Participants filled in a health questionnaire between 1993 and 1997 and nurses conducted a medical exam at a clinic. Participants scored a point each for not smoking, regular physical activity, eating five servings of fruits and vegetables a day and moderate alcohol intake.

Until 2006, the researchers tracked deaths from all causes, including cardiovascular disease, cancer and respiratory diseases. People who scored four points were four times less likely to die than those who scored zero, the research showed.

Khaw said 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 help people 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.

Changing these little things might be easier said than done. Smoking is physically addictive and eating habits are often formed early in life.

"They've always eaten a certain way, and it's very difficult to change the status quo," said Dr. Jerrell Driver, a pyschologist in Jackson. "It often requires a total change in life styles as opposed to just breaking a certain habit."

To stop smoking, he suggested replacing it with a healthy habit, like exercising. Keep track of the weight you loose and it will serve as "a reminder that you've given up something detrimental" to encourage you to continue, Driver said.

Because the study only observed people rather than testing specific changes, experts said 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 Armstrong. "The 14 years is an average across the population of what's theoretically possible."

Southeast Missourian writer Chris Harris contributed to this report.