Explaining why dark chocolate is good for the heart, researchers said that it increases the flexibility of arteries and also prevents white blood cells from sticking to the walls of blood vessels.

The flexibility of arteries and white blood cell adhesion play a significant role in atherosclerosis. Researchers of a new study found that dark chocolate can restore the flexibility of arteries and also prevents white blood cells from sticking to the walls of the blood vessels.

"We provide a more complete picture of the impact of chocolate consumption in vascular health and show that increasing flavanol content has no added beneficial effect on vascular health," said Diederik Esser, Ph.D., a researcher involved in the work from the Top Institute Food and Nutrition in a press statement. "However, this increased flavanol content clearly affected taste and thereby the motivation to eat these chocolates. So the dark side of chocolate is a healthy one."

For the study, researchers examined 44 middle-aged overweight men over two periods of four weeks as they consumed 70 grams of chocolate per day. Study participants received either specially produced dark chocolate with high flavanol content or chocolate that was regularly produced. Both chocolates had a similar cocoa mass content. Before and after both intervention periods, researchers performed a variety of measurements that are important indicators of vascular health.

During the study, participants were advised to refrain from certain energy dense food products to prevent weight gain. Scientists also evaluated the sensory properties of the high flavanol chocolate and the regular chocolate and collected the motivation scores of the participants to eat these chocolates during the intervention.

"The effect that dark chocolate has on our bodies is encouraging not only because it allows us to indulge with less guilt, but also because it could lead the way to therapies that do the same thing as dark chocolate but with better and more consistent results," said Gerald Weissmann, M.D., Editor-in-Chief of The FASEB Journal. "Until the 'dark chocolate drug' is developed, however, we'll just have to make do with what nature has given us!"

The findings of this study were published online in the March issue of The FASEB Journal.