Want to live a long and healthy life? Make sure you eat chocolate, and drink tea and coffee in moderation daily, says a leading nutritional scientist.

Yes, according to Prof Gary Williamson of University of Leeds, chocolate, tea and coffee are among some key foods and beverages needed to live a long and healthy life, British newspaper 'The Daily Telegraph' reported.

In fact, Prof Williamson has prepared a list of 20 "lifespan essential" foodstuffs - all are rich in naturally occurring chemicals, known as polyphenols, which have been linked to a variety of health benefits, including protection against heart disease.

And, these foods and drinks could also help to slow down the ageing process by helping to protect cells from the natural damage that occurs over time, he has suggested.

Prof Williamson said: "Epidemiology studies support the protective effects of polyphenol-rich foods. Lack of these components in the diet because of low intake of fruit and vegetables, increases the risk of chronic disease.

"This means that they are essential to fulfil the maximum individual lifespan, and so I propose that they are 'lifespan essential'.

"Although they might not be essential for growth and development or the maintenance of major body functions, there is increasing knowledge concerning their potential for health maintenance or disease risk reduction throughout adulthood and during ageing."

Even a recent study carried out by scientists in the US, Britain and Australia concluded that polyphenols can help protect against heart disease.