Dark Chocolate, when consumed in moderation, is known to maintain good heart health and scientists now know why.

Researchers from Top Institute Food and Nutrition and Wageningen University in the Netherlands found that dark chocolate helps restore flexibility to arteries while also preventing white blood cells from sticking to the walls of blood vessels.

Arterial stiffness and white blood cell adhesion are known factors that play a significant role in atherosclerosis, a disease in which plaque builds up inside arteries. Scientists also found that increasing the flavanol content - an ingredient believed to improve blood vessel and brain activity - of dark chocolate did not change this effect.

"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," Diederik Esser, a researcher involved in the work from the Top Institute Food and Nutrition and Wageningen University, Division of Human Nutrition in Wageningen, The Netherlands. "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."

To make this discovery, researchers analyzed 44 middle-aged overweight men for two periods of four weeks as they consumed 70 grams of chocolates per day. Study participants received either specially produced dark chocolate with high flavanol content or chocolate that was regularly produced. Before and after both intervention periods, researchers performed a variety of measurements that are important indicators of vascular health.

Researchers 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," Gerald Weissmann, M.D., Editor-in-Chief of The Federation of American Societies for Experimental Biology Journal, said in a statement. "Until the 'dark chocolate drug' is developed, however, we'll just have to make do with what nature has given us!"