The following correction was printed in the Guardian's Corrections and clarifications column, day month date year Friday January 11 2008

The article below stated in error that a Cambridge University study monitoring the health of men and women in Norfolk found that neither social class nor body mass index had a role to play in life expectancy. In fact the research findings were adjusted for age, sex, body mass index, and social class.

People who adopt four principles for a healthy lifestyle can add as much as 14 years to their lives, a study revealed today.

Researchers found that not smoking, taking exercise, drinking in moderation and eating five servings of fruit and vegetables a day can have a huge impact on life expectancy.

Academics at Cambridge University monitored the health of 20,000 men and women aged between 45 and 79 from Norfolk between 1993 and 2006.

The study concluded: "The results strongly suggest that these four achievable lifestyle changes could have a marked improvement on the health of middle-aged and older people, which is particularly important given the ageing population in the UK and other European countries."

The research showed that a person's social class or body mass index (BMI) had no role to play in life expectancy.

The study, published in the journal The Public Library of Science Medicine, is one of the first to look at the combined impact of the four factors on life expectancy.

Participants, none of whom was known to have cancer or heart disease at the start of the study, were awarded a point for each of their four healthy behaviours.

These were determined as not smoking, not being physically inactive (defined as having a sedentary job and not doing any recreational exercise), drinking less than 14 units of alcohol (seven pints of beer) a week, and having a vitamin C level equivalent to eating five servings of fruit or vegetables a day.

After factoring in age, the results showed that, over an average period of 11 years, people with a score of nil - those who did not undertake any of these healthy forms of behaviour - were four times more likely to have died than those who had scored four.

The researchers calculated that a person with a health score of nil had the same risk of dying as someone 14 years older who had scored four in the questionnaire for engaging in all four healthy behaviours.

Smoking had the biggest single impact on people's health, with smokers 77% more likely to have died during the study.

Eating plenty of fruit and vegetables came next, with high vitamin C levels giving people a 44% better chance of being alive by the end of the study.

A low alcohol intake improved people's chance of survival by 26% and being physically active by 24%.