The scientists recommend a diet rich in fruit and vegetables

A study by the Universities of Bristol and London suggests eating antioxidant vitamins does not prevent the diseases.

Factors like living in deprived social circumstances and whether you are a smoker, rather than taking vitamin supplements, affect susceptibility.

However, people who have diets rich in vitamins A, C and E are less likely to have suffered deprived circumstances.

Bristol University's Dr Debbie Lawlor and colleagues reviewed previous studies and undertook new research for the study.

'Physically active'

This new research found that even the job a person's father did and household conditions in childhood were strong predictors of levels of antioxidant vitamins in the blood.

People with high levels of antioxidant in their blood are also less likely to have ever smoked, more likely to be physically active and less likely to be obese.

The study was conducted in 4,000 women from all over Britain who had blood tests when they were 60-70 years old.

Dr Lawlor said: "People should be encouraged to eat a healthy diet with plenty of fruit and vegetables and of course should take regular exercise and should not smoke.

"But there is no evidence that taking vitamin supplements will prevent heart disease or cancer."