Nutritionists have long said that eating dark chocolate in moderation can be good for our health. Now, researchers have discovered why. It may reduce the risk of atherosclerosis – thickening and hardening of the arteries – by restoring flexibility of the arteries and preventing white blood cells from sticking to the blood vessel walls.

The research team, including Prof. Diederik Esser of the Top Institute Food and Nutrition and the Division of Human Nutrition at Wageningen University, both in the Netherlands, published the study in The FASEB Journal.

To reach their findings, the investigators analyzed 44 overweight men aged between 45 and 70 years.

Over two periods of 4 weeks, the men were required to eat either 70 g of regular dark chocolate each day or 70 g of specially produced dark chocolate with high levels of flavanol – a naturally occurring antioxidant found in some plants, including the cocoa plant. Both chocolates were similar in their cocoa content.

Subjects were asked not to eat other foods high in calories during the study period, in order to prevent them from gaining weight.

The researchers assessed how both the chocolate high in flavanols and the regular chocolate stimulated the participants’ senses over the study duration. In other words, they looked at whether flavanol content motivated the subjects to eat the chocolate.

The vascular health of the participants was assessed both at the baseline and end of the study period.

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Researchers say eating dark chocolate may reduce the risk of atherosclerosis – the hardening and thickening of the arteries.

Results of the study revealed that both groups showed a 1% decrease in flow-mediated dilation (FMD), a 1% decrease in augmentation index (AIX), reduced leukocyte (white blood cell) count, decreased plasma sICAM1 and sICAM3, and a reduced leukocyte adhesion marker expression.

This means the consumption of dark chocolate lowered participants’ risk of atherosclerosis – a condition that can be caused by arterial stiffness and white blood cell adhesion.

However, the researchers found that although the chocolate higher in flavanols increased sensory stimulation in participants, both types of chocolate produced the same heart benefits.

These findings challenge previous research suggesting that flavanols have health benefits. Medical News Today recently reported on a study stating that consuming foods high in flavanols, such as chocolate, wine and berries, may protect against type 2 diabetes.

Commenting on the findings, Prof. Esser says:

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.

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.”

Dr. Gerald Weissman, editor-in-chief of the The FASEB Journal, says these findings could lead to new therapeutic treatments that provide the same benefits as dark chocolate consumption, but with “better and more consistent results.”

“Until the ‘dark chocolate drug’ is developed, however, we’ll just have to make do with what nature has given us,” he adds.

Other research has linked chocolate consumption to many other health benefits. Last year, we reported on a study suggesting that drinking two cups of hot chocolate a day may prevent memory decline, while a 2012 study found that eating moderate amounts of chocolate could reduce the risk of stroke.