Four out of ten people are unaware that eating a poor diet increases their risk of cancer, a survey reveals.

The poll of almost 2,000 people found that 41 per cent were unaware of the link between what they ate and the disease.

Only about one in three people knew that eating processed meat increased their cancer risk, while 44 per cent were unaware that being overweight was another risk factor.

But 42 per cent of those questioned knew that not taking enough exercise or being physically active increased their risk of cancer.

Research shows that maintaining a healthy weight is the most important thing a person can do to prevent cancer after giving up smoking.

Excess body fat is linked to six types of cancer, including bowel cancer and postmenopausal breast cancer, and scientists also recommend people cut down on their intake of salt, alcohol and high-calorie foods.

Lisa Cooney, head of education for the World Cancer Research Fund, which commissioned the survey, said: "The scientific evidence is clear that people can reduce their risk of cancer through eating healthily and reducing their intake of things like alcohol and processed meat.

"But these results show that there are still millions of people in Britain who are unaware of how they can take simple steps to reduce their cancer risk.

"This means they are not in a position to make informed lifestyle choices."