Claims that dark chocolate is good for you may be misleading, according to health experts.

Plain chocolate is naturally rich in flavanols, plant chemicals believed to protect the heart.

But an editorial in The Lancet medical journal today says that many manufacturers remove flavanols from chocolate because of the bitter taste.

As a result, dark chocolate might contain no flavanols while at the same time being rich in fat and sugar, both potentially harmful to heart and arteries.

The Lancet's editorial follows research published last month in the journal Circulation, which showed that flavanol-rich chocolate had a beneficial effect on circulation.

In a study led by Dr Andreas Flammer of the Cardiovascular Centre, Zurich, it was found that flavanol-rich chocolate caused blood vessels to open up and improved heart function in 11 heart-transplant patients.
 

However, The Lancet says there is a catch for lovers of dark chocolate.

Contrary to what one might expect, dark chocolate might not necessarily contain flavanols since cocoa solids can be darkened after flavanols are removed.

"When chocolate manufacturers make confectionery, the natural cocoa solids can be darkened and the flavanols, which are bitter, removed, so even a dark-looking chocolate can have no flavanol," says the article.

"Consumers are also kept in the dark about flavanol content of chocolate because manufacturersrarely label their products with this information."

It adds that even when there are flavanols, "the devil in the dark chocolate" is the fat, sugar and calories.

"Those who eat a moderate amount of flavanol-rich dark chocolate will have to balance the calories by reducing their intake of other foods," The Lancet editorial concluded.

"So with the holiday season upon us, it might be worth getting familiar with the calories in a bar of dark chocolate versus a mince pie and having a calculator at hand."