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Heart Association Study Finds Dark Chocolate Benefits Circulation

By Erik Derr staff@sciencetimes.com | Jul 08, 2014 10:51 PM EDT

Those who espouse the health benefits of dark chocolate have another reason to cheer, with new research from the American Heart Association asserting the rich confection may benefit leg circulation.

Of course, it's not the chocolate but its polyphenols -- specific compounds in the cocoa from which the chocolate is crafted -- that findings recently published in the Journal of the AHA found may help "reduce oxidative stress and improve blood flow in peripheral arteries," which carry blood to the legs, stomach, arms and head, according to a news release.

Peripheral artery disease, or PAD, causes the peripheral arteries to narrow, most commonly in the legs. Reduced blood flow can lead to pain, cramping and fatigue in legs and hips while walking.

The pilot study included 14 men and six women ages 60 to 78, all diagnosed with PAD. The participants were able to walk longer unassisted after eating dark chocolate, but not after eating milk chocolate.

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Study subjects were "tested on a treadmill in the morning and then two hours after eating 40 grams" of dark chocolate, about the size of an average American plain chocolate bar. On a separate day, they repeated the test with milk chocolate.

The dark chocolate contained more than 85 percent cocoa, ensuring it was loaded with polyphenols, while the milk chocolate's cocoa content was below 30 percent, meaning far fewer polyphenols.

After eating dark chocolate, the participants walked an average 11 percent farther (39 feet) and 15 percent longer (17 seconds) than they could earlier that day. Milk chocolate didn't improve their distance or time.

The research revealed levels of nitric oxide, a gas the release notes is "linked to improved blood flow," increased when participants ate dark chocolate. And other "biochemical signs of oxidative stress" were lower.

The results, coupled with other experiments, suggest higher nitric oxide levels may dilate peripheral arteries and improve walking independence.

The performance boost was modest, but dark chocolate polyphenols are "of potential relevance for the quality of life of these patients," Lorenzo Loffredo, the study's co-author and assistant professor at Italy's Sapienza University of Rome, said in the release.

Said physician Francesco Violi, the study's senior author and a Sapienza University internal medicine professor: "Polyphenol-rich nutrients could represent a new therapeutic strategy to counteract cardiovascular complications."

The researchers noted the findings need to be confirmed in a larger study involving long-term consumption, as the latest experimentation lacked a placebo group -- and participants knew which kind of chocolate they were given, which could have influenced the results.

AMA spokesman Mark Creager said it's too early to recommend polyphenols or dark chocolate for cardiovascular health.

"Other investigations have shown that polyphenols, including those in dark chocolate, may improve blood vessel function. But this study is extremely preliminary, and I think everyone needs to be cautious when interpreting the findings," said Creager, who directs the Vascular Center at Boston's Brigham and Women's Hospital and teaches medicine at Harvard Medical School.

"We know from other studies of antioxidants -- vitamin C and vitamin E, for example -- that these interventions have not gone on to show improvement in cardiovascular health."

Because chocolate adds calories to one's diet, the AMA, regardless of the findings about dark chocolate, recommends that "men consume no more than 150 calories per day from added sugars (9 teaspoons) and women should consume no more than 100 calories (6 teaspoons) from added sugar per day and 5 percent -6 percent of calories from saturated fat. A typical American chocolate bar provides 94 calories from sugar (24 grams) and 8 grams of saturated fat."

Other polyphenol-rich foods, including cloves, hazelnuts, dried peppermint, capers and celery seeds, contain far lower levels of added sugar, saturated fats and calories than does dark chocolate, the AMA release said.

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