Our findings suggest that an increase in dietary intake of foods rich in ascorbic acid might have benefits for cardiovascular disease and all-cause mortality in men and women

Professor Kay-Tee Khaw, of Cambridge University

He found that with just a 50 gramme increase in fruit or vegetables it was possible to cut the death rate by 20%, regardless of the person's age, blood pressure or whether they smoked.

Vitamin C, or ascorbic acid, is commonly used to boost the immune system to ward off colds and the flu, and is an antioxidant that destroys harmful substances in the body, called free radicals, that can cause cancer.

Fresh fruit such as oranges, grapefruit, apples and bananas and green vegetables are good sources of vitamin C.

Healthy eating

Vitamin C was also linked with a cut in cancer-related deaths among men.

Professor Kay-Tee Khaw said his findings in the Lancet could have a positive effect on the nation's health if people start to eat more healthily.

He said: "Our findings suggest that an increase in dietary intake of foods rich in ascorbic acid might have benefits for cardiovascular disease and all-cause mortality in men and women and add to the large amount of evidence that lends support to the health benefits of fruit and vegetables.

"Small and feasible changes within the normal population range of intake could have a large effect," he said.

A spokeswoman for the British Heart Foundation said the study confirmed the benefits of fruit and vegetables.

She said: "This study contributes to a large body of research suggesting that vitamin C is cardioprotective.

Powerful antioxidant

"Vitamin C is a powerful antioxidant and is found in many fruit and vegetables. Antioxidants prevent cholesterol from 'oxidising' - the process that leads to the furring up of the arteries."

But she said that more work is needed to establish whether vitamin C supplements have a positive effect on health.

"A balanced diet containing at least five portions of fruit or vegetables daily will provide all the vitamin C that the body needs, plus many more beneficial vitamins and minerals.

"However, more evidence is needed to establish whether vitamin C supplements offer the same benefits as good old fruit and veg."