A Cambridge University study looked at over 25,000 people and found that making small changes to lifestyle can have a significant impact on how long people will live.

Researchers at the University of Cambridge and the Medical Research Council studied 20,000 men and women from the city of Norfolk who were between the ages of 45 and 79 in the years between 1993 and 1997. The participants filled out questionnaires tracking their health habits. Then, their death rates were recorded until 2006. The study was reported in the January 8, 2008 edition of the journal PLOS Medicine . It is part of the European Prospective Investigation into Cancer and Nutrition (EPIC), conducted in 10 European countries. EPIC is the largest-ever study of diet and health.

These latest results from the study showed eating five portions of fruit and vegetables a day can give you the life expectancy of someone three years younger.

Not smoking turned the clock back by four to five years.

Even increasing exercise by a moderate amount can take up to three years off.

But the amount of exercise someone would need to do to achieve that depends on their job.

An office worker would need to do one hour of exercise, such as swimming or jogging, every day, while a person with a moderately active job, such as a hairdresser, would need to take 30 minutes exercise a day.

People with active jobs, including nurses and bricklayers, do not need to do any extra exercise - as their work is strenuous enough.

Professor Kay-Tee Khaw, who led the study, said: "Many of us find it difficult to change our usual lifestyle. "However, there is increasing evidence that even relatively small changes can make a big difference to our health and well being." "Eating an extra piece of fruit or walking up the stairs can help people add years to their lives."

The four behaviors - not smoking , performing regular exercise , drinking moderate amounts of alcohol and eating five servings of fruit and vegetables a day - had each been independently shown to increase lifespan, but this was the first study to examine their combined value.