Peripheral artery disease, or PAD, is a circulatory problem which occurs when plaque builds up in the arteries and as a result reduces blood flow to other parts of the body. PAD often affects the arteries of the legs and this eventually leads to its common symptom of leg pain when walking.

The Centers for Disease Control and Prevention estimates that there are 8 million individuals in the U.S. suffering from PAD, up to 20 percent of whom are 60 years old and over. A new study, however, may be able to bring relief to people who have difficulty walking because of the poor blood flow to their legs as it found that eating dark chocolates may help seniors with PAD to walk longer and farther.

For the study which was published in the Journal of the American Heart Association on July 2, Lorenzo Loffredo, from the Sapienza University in Rome, and colleagues asked 20 patients with peripheral artery disease, who were 69 years old on average, to walk on a treadmill for as long as they can and then had them randomly eat a 40g bar of either a dark or milk chocolate.

Two hours later, the participants took the same treadmill test that they did earlier. The researchers observed that while there were no changes in the time and distance walked by the participants who ate milk chocolate, those who ate dark chocolate walked about 17 second longer and 39 feet farther in their second treadmill session.

The researchers also found that the levels of nitric oxide, a type of gas in the blood that is associated with improved blood flow, were also higher in those who ate dark chocolate than those who had milk chocolate.

Loffredo and colleagues suggested that the elevated levels of nitric oxide levels may have widened the peripheral arteries and helped improve the ability of the patients to walk.

"In PAD patients dark but not milk chocolate acutely improves walking autonomy with a mechanism possibly related to an oxidative stress‐mediated mechanism involving NOX2 regulation," the researchers wrote.

The researchers noted that the dark chocolates they used in the study were made up of more than 85 percent cocoa making them rich in polyphenols, antioxidants that are believed to improve blood flow by prompting biochemical changes in the body that leads to the widening of the arteries. The milk chocolate they used, on the other hand, has less than 30 percent cocoa content.