A wayward band of chocoholics has accidentally proved to medical science what aficionados must have always hoped - that chocolate can be good for you.
Researchers in the United States found that human guinea pigs who broke the rules of a study on blood clots by eating dark chocolate increased their protection against heart attacks.
Johns Hopkins University in Baltimore enrolled 1,200 people across the US for an 18-month study on the impact of aspirin on blood platelets, the sticky cells that generate clots.
But it asked participants to refrain from a number of foods, including chocolate, known to affect platelets.
A group of 139 people could not give up chocolate, so the scientists decided to monitor its effect.
The study concluded that snacking on just two tablespoonfuls of dark chocolate a day reduced the development of potentially fatal blood clots.
Diane Becker, the lead researcher, said: "What these chocolate 'offenders' taught us is that the chemical in cocoa beans has a biochemical effect similar to aspirin in reducing platelet clumping, which can be fatal if a clot forms and blocks a blood vessel, causing a heart attack."
She stressed that the latest findings, presented at the American Heart Association's annual scientific sessions in Chicago, did not mean people should consume vast numbers of sugary chocolate bars.
"Eating a little bit of chocolate or having a drink of hot cocoa as part of a regular diet is probably good for personal health, so long as people don't eat too much of it, and too much of the kind with lots of butter and sugar," she said.
The research, by the university's School of Medicine and Bloomberg School of Public Health, is likely to increase the popularity of dark chocolate in the UK.
Bolstered by its health credentials and by the reputation of the organic brand Green and Blacks, dark chocolate almost overtook sales of milk chocolate at Waitrose last year.
The marketing departments of chocolate-makers are eager to strengthen the link between their products and healthiness in the public's mind. And academic research over the past two decades has certainly helped.
In 2004, the University of California found that eating 46 grams of flavanoid-rich chocolate daily increased the ability of blood vessels to dilate.
Last year, a study published in the journal Heart found that dark chocolate had proportionately more antioxidants than other foods better known for their health-giving properties, such as red wine, green tea and berries.
Mars marketed a range of bars in the US as a way to get healthy while munching premium chocolate with the boast: "Now you can have real chocolate pleasure with real heart health benefits."
But the boast for CocoaVia bars fell foul of the US Food and Drug Administration, which warned Mars that it should not claim that they promoted coronary health. "These claims are false or misleading because of the high levels of saturated fat in the products," the FDA ruled.
Amid a flat market for milk chocolate bars, the leading British confectioner Cadbury's is planning to capitalise on the trend for dark and more premium chocolate. Cadbury Schweppes' chief executive, Todd Stitzer, told The Grocer magazine recently: "We are relaunching Bournville next year and trying to take advantage of the well-being element." The company will also launch a new Dairy Milk bar with double the level of cocoa solids.
Sales of confectionery in the UK are £4bn. Britons eat more chocolate than any other country in Europe.
According to Alan Porter, the chairman of the Chocolate Society, a more sophisticated chocolate culture has taken hold in Britain and people are moving away from the mass market brands that are saturated with vegetable oil.
Last month, the Chocolate Society introduced three new bars made from single cocoa estates in Venezuela, Trinidad and Madagascar.
Mr Porter said: "Fine chocolate painstakingly produced from natural ingredients is every bit as sophisticated as a great claret or single malt. Each has its own distinctive flavour, aroma and character.
"Soaring sales of dark chocolate reveals that Britons are starting to take their chocolate more seriously."
A taste of history
* The Mayans started the first cocoa plantations in South America in about 600BC. They turned the cocoa beans into a drink they called xocoatl.
* In 1505, Christopher Columbus brought cocoa beans back to Spain from his fourth voyage to America.King Ferdinand of Spain was not impressed.
* After the Spanish conquest of Mexico, Hernando Cortes returned to Spain in 1528 with secret chocolate-making equipment. Production took place in monasteries and stayed secret in Europe for a century.
* Chocolate was drunk rather than eaten in Britain until the Cadbury brothers brought in solid chocolate in 1849.
* About 99 per cent of British households now eat confectionery, Nestlé says.
* Sales of dark chocolate are expected to rise about 48 per cent by 2010.Reuse content