Researchers have found that low levels of vitamin C - which is found in fruit and vegetables - are associated with higher death rates from heart disease and strokes in men and women, and with some cancers in men.

Modest increases in fruit and vegetable intake of just one or two servings a day may be associated with large benefits for health

Professor Kay-Tee Khaw

The results hold true regardless of people's age, blood pressure or whether or not they've smoked.

They raise the possibility that increasing the amount of fruit and vegetables in the diet might have a beneficial effect in preventing disease.

In fact, the charity Cancer Research UK says that if people ate just one apple or orange a day it could cut their risk of dying early from cancer or other diseases by 20%.

Major study

The research is part of the ongoing European Prospective Investigation into Cancer and Nutrition (EPIC) which involves more than 500,000 people in 10 countries.

It aims to produce more detailed information than ever before on the link between diet and cancer.

Professor Kay-Tee Khaw, one of the principal investigators from Cambridge University, said: "The findings indicate that modest increases in fruit and vegetable intake of just one or two servings a day may be associated with large benefits for health."

Sir Paul Nurse, Interim Chief Executive of Cancer Research UK, said: "These early results are promising and add to the growing evidence that increasing the amount of fruit and vegetables that we eat may have a protective effect from cancer."

The charity is backing a campaign to encourage people to eat five portions of fruit and vegetables a day.

The research included a survey of 30,000 men and women aged 49-79 from Norfolk whose health is being continuously monitored.

Their blood vitamin C levels were measured not to assess any protective effects from the vitamin but to provide an indication of fruit and vegetable consumption.