Not even Willy Wonka, Roald Dahl’s eccentric chocolate-maker, could have dreamt that his scrumptious products might one day offer the world a panacea.

But scientists are close to claiming just that. A compound in unrefined cocoa has health benefits that may rival those of penicillin and anaesthesia, they say.

Norman Hollenberg, professor of medicine at Harvard Medical School, has spent years studying the Kuna people in Panama. He found that four of the most common killers - stroke, heart disease, cancer and diabetes - affected fewer than one in 10 of the Kuna.

Unrefined natural cocoa contains high levels of epicatechin, which Professor Hollenberg said was so important it should be considered a vitamin.

He told Chemist and Industry magazine: “If these observations predict the future, then we can say without blushing they are among the most important observations in the history of medicine. We all agree that penicillin and anaesthesia are enormously important. But epicatechin could potentially get rid of four of the five most common diseases in the Western world. How important does that make epicatechin? I would say very important.”

Daniel Fabricant, vice-president at the Natural Products Association, said that the observations might warrant a rethink of how vitamins are defined. There are 13 vitamins that are defined as essential to the normal functioning, metabolism and regulation of cell growth, and deficiency is usually linked to disease.

“The link between high epicatechin consumption and a decreased risk of killer disease is so striking, it should be investigated further. It may be that these diseases are the result of epicatechin deficiency,” Mr Fabricant said.

Epicatechin is a flavanol and is also found in tea, wine, chocolate and some fruits and vegetables. Flavanols are removed from commercial cocoas because they tend to have a bitter taste. The milk and sugar with which they are commonly drunk in developed countries also undermines their health-giving properties.

Cocoa that retains its flavanols, used to make dark “bitter” chocolate, improves blood supply to the brain and may boost short-term memory. Researchers in Nottingham showed that drinking flavanol-rich cocoa boosted blood flow for two to three hours.

Ian Macdonald, who led the study presented to the American Association for the Advancement of Science in San Francisco last month, said: “This raises the possibility of enhancing brain function among older adults or for others in situations where they may be cognitively impaired, such as fatigue or sleep deprivation.”

A history of chocoholism

* The first people believed to have grown cocoa beans were the Olmec Indians, around 1500BC.

* Cocoa beans were used by the Aztec civilisation to make a frothy, quite bitter hot drink that is nothing like the modern, sweet-tasting chocolate.

* Cocoa beans contain several hundred flavour compounds.

* Britons each eat 10kg (22lb) of chocolate a year - more than any other European nation.

* The Englishman Joseph Fry created the first chocolate bar in 1847.

* Last year, Britons spent £4.3bn on chocolate.