Most people have heard that chocolate is good for you. But now, the medical journal Lancet is bursting the chocolate bubble.

Just in time for the holidays, a Lancet editorial published recently notes that there won't be a "truffle treatment" for heart disease any time soon. In fact, the editors point out that the very thing that makes chocolate good for you — the antioxidants called flavanols – also make chocolate taste bitter. As a result, confectionery makers often take out the flavanols, stripping the chocolate of its main health-promoting properties. Worse, labels usually don't tell you whether your chocolate comes with or without flavanols, making it tough to know if a particular piece of chocolate has any health benefits at all.

This depressing news comes just a month after Circulation, the medical journal for the American Heart Association, created a stir when it reported a study of 22 heart transplant patients who were given a dose of dark chocolate or fake chocolate. Just two hours after eating the real thing, patients had measurable improvements in blood flow and vascular function and less clotting, compared to placebo chocolate eaters, who experienced no changes.

The Circulation report is the latest in a string of studies touting the benefits of chocolate. The flavonoids in chocolate, which include the antioxidants called flavanols, are similar to those found in tea, red wine and some fruits and vegetables, foods also known for their heart-healthy effects.

To boost your chances of getting a flavanol-rich bar, the best bet is to look for very dark chocolate with few added ingredients, notes Dr Jacob Shani, chairman of the Cardiac Institute at Maimonides Medical Centre in Brooklyn, NY.

The darker the chocolate, the higher it's likely to be in flavonoids, according to the February issue of Mayo Clinic Health Letter. A typical bar of dark chocolate contains an average of 53.5 milligrams of flavonoids. A milk chocolate bar contains less than 14 milligrams, while white chocolate doesn't have any, according to the Mayo report.

But even if your chocolate is loaded with flavanols, it won't be a wonder drug. Most studies show only modest benefits from chocolate, and even though it's good for you, you still have to pay attention to calories and fat.

"If you ask me what's more important, a little physical activity like walking or eating the chocolate, go take your walk," said Dr. Shani. "I don't think in the very near future we're going to tell every patient go ahead and eat lots of chocolate. That would be too good to be true." NYT