People with narrowed leg arteries could walk farther and for longer amounts of time after eating dark chocolate.
Cocoa contains polyphenols, which can reduce oxidative stress and improve blood flow in the peripheral arteries. Oxidative stress is a bodily imbalance that can lead to inflammation and blood vessel damage, the American Heart Association reported.
Association researchers looked at 14 men and six women between the ages of 60 and 78 suffered from peripheral artery disease (PAD). The condition can cause symptoms such as pain, cramping, and fatigue in the legs.
Participants were asked to do a treadmill test in the morning and then later in the day after eating 40 grams of chocolate.
After eating dark chocolate the participants were able to walk 39 feet farther and for about 17 more seconds on average then they had that morning. Their ability to walk did not improve after eating milk chocolate.
"[The benefit of dark chocolate is] of potential relevance for the quality of life of these patients," said Lorenzo Loffredo, M.D., the study's co-author and assistant professor at the Sapienza University of Rome in Italy.
The researchers also found levels of nitric oxide, which is linked to improved blood flow, were higher after the patients consumed dark chocolate.
"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," American Heart Association spokesperson Mark Creager, M.D. said.
"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," he explained.
Other polyphenol-rich foods with less sugar and calories than chocolate include: "cloves, dried peppermint, celery seed, capers, and hazelnuts," the American Heart Association reported.