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Dark chocolate improves walking in patients with peripheral artery disease

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About 20% of seniors aged 75 or older in Western nations suffer from peripheral artery disease. When walking, leg cramps often force them to stop. In addition, because they also have atherosclerosis in other areas, they are at risk for heart attacks and strokes. A new study has found that dark chocolate improves walking ability in these individuals. The study was published online on July 3 on in the Journal of the American Heart Association by researchers at Sapienza University of Rome (Rome, Italy) and IRCCS NeuroMed (Pozzilli, Italy).

The study authors note that a substance known as NOX‐2 is known to decrease arterial blood flow. Dark chocolate produces arterial dilatation by down‐regulating (diminishing) the effect of NOX-2. The goal of the study was to determine whether dark chocolate improves walking ability in patients with peripheral artery disease.

The study group comprised 20 patients with peripheral artery disease (14 males and 6 females; average age: 69 ± 9 years). The subjects were randomly assigned to receive 40 grams (1.4 ounces), which contained more than 85% cocoa, or 40 grams of milk chocolate, which contained less than 35% cocoa. It was a cross‐over design, meaning that both groups consumed dark chocolate during the study.

The investigators measured serum levels of isoprostanes (nitrite/nitrate (NOx) and sNOX2‐dp), which are a marker of blood NOX2 levels. The subjects were asked to walk on a treadmill for as long as possible. The treadmill was set at about 2.2 miles per hour and a 12% grade. Their maximal walking distance and maximal walking time were assessed. The aforementioned isoprostanes were measured at baseline and two hours after consuming the chocolate.

The researchers found that dark chocolate intake significantly increased maximal walking distance and maximal walking time and significantly decreased serum isoprostanes. No changes in these values were found in the group that consumed the milk chocolate. Furthermore, serum epicatechin and its methylated metabolite significantly increased only after dark chocolate ingestion. They also conducted a laboratory study (substances were mixed in the laboratory) that supported their findings.

The authors concluded that in patients with peripheral artery disease, dark but not milk chocolate promptly improved walking ability. This was accomplished via a mechanism possibly related to an oxidative stress‐mediated mechanism involving NOX-2 regulation.