No, your eyes are not deceiving you. According to recent research from US scientists, chocolate has joined the unpronounceable trio of goji berries, spirulina and acai berries on the list of superfoods that could prolong your life. It seems those chocoholics we've been tutting disapprovingly at for years were on to a good thing all along.

Chang Lee, the chairman of the Department of Food Science and Technology at Cornell University in the US has been studying the healthy properties of cocoa for years. Lee and his team found that cocoa has nearly twice as many antioxidants as red wine, and up to three times as many as green tea. These results surprised even the team.

"If I had made a prediction before conducting the tests, I would have picked green tea as having the most antioxidant activity." said Lee. "When we compared one serving of each beverage, the cocoa turned out to be the highest in antioxidant activity, and that was surprising to me."

The healthy properties of antioxidants are still a topic for hot debate in the scientific community, but there is considerable laboratory evidence from chemical, cell culture and animal studies showing that antioxidants may slow down or even prevent the development of cancer. Other studies have indicated benefits in heart disease and other age-related conditions. Of antioxidants, the "best" performer seems to be polyphenols - which are also the least researched. Cocoa contains polyphenols, which are also found in grapes, berries and wine - as well as catechins and epicatechins - found in green tea.

But if this seems all a bit too good to be true, then yes, there is a catch. Before you rush out to the newsagent for a bar of Dairy Milk, remember this is cocoa they are talking about, not milk chocolate.

"Further research is needed before the beneficial effects can really be proved by the consumption of chocolate in the diet, rather than in the high quantities used in the lab," warns Anna Denny of the British Nutrition Association. "And eating too much chocolate is not recommended anyway due to the high fat and sugar content. Plus there is tooth decay."

However in more good news, Denny says "chocolate is also a good source of iron, magnesium and phosphorus. Dark, more cocoa rich, chocolate contains more iron than white chocolate."

So, the answer is to tuck into a bar with a high cocoa content - and only in moderation. The lower the cocoa content of a bar, the more calories and saturated fat it will contain. 100% cocoa contains, per 100g, about 250 calories and 24g of fat - of which only 1.6g is saturated. But down the other end of the scale, 100g of Snickers bar would contain twice as many calories - at 501 - and 8.5g of saturated fat.

If you've ever tried eating 100% cocoa chocolate, chances are you might not want to make a habit of it. Instead, cover all your bases with a cup of cocoa in the morning, a glass of red wine with your evening meal, and a mug of green tea before bed.