Medscape Multispecialty
July 02, 2014
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PAD: Dark Chocolate May Make Walking Easier – from MedPageToday
Maybe we should go on a chocolate-study-news diet – Not so fast
ROME, ITALY — Shortly after eating the equivalent of a small bar of dark, but not milk, chocolate, patients with moderate to severe peripheral arterial disease (PAD) could walk slightly farther and longer on a treadmill before having to stop due to pain, in a proof-of-concept study[1].
The research suggests that polyphenols in the dark chocolate may improve circulation in PAD patients, but further study is needed to confirm this, according to lead author Dr Lorenzo Loffredo (Sapienza University of Rome, Italy), senior author Dr Francesco Violi (Sapienza University of Rome), and colleagues. Two hours “after eating the dark [but not the milk] chocolate, PAD patients walked an average of 11% farther and 15% longer” than when they did not eat chocolate, Drs. Loffredo and Violi noted in an email to heartwire .
“PAD is characterized by reduced flow to the limbs, [and so far] there are no drugs that improve this blood flow, but dark chocolate could [potentially do this].” However, “this is only a pilot study,” they stressed. On the other hand, “if the results of our study are confirmed by future studies with chronic ingestion of polyphenols, it would open up novel therapeutic strategies in this setting using a natural substance,” they said.
The study is published July 2, 2014, in the Journal of the American Heart Association.
Polyphenols, Oxidative Stress, and PAD
PAD typically manifests in patients as intermittent claudication, where blood flow to the limbs is impaired during exercise, likely partly due to impaired nitric-oxide generation and oxidative stress. Patients experience weakness, numbness, or cramping in their muscles due to decreased blood flow.
However, cocoa and dark chocolate, which are rich in polyphenols, dilate arteries by reducing oxidative stress and increasing nitric-oxide generation. The researchers hypothesized that patients with PAD could walk farther and longer before experiencing leg cramps if they first ingested cocoa.
They recruited 20 patients—14 men and 6 women—who had Fontaine stage IIb PAD, meaning they had leg pain when they walked less than 200 m, about half the length of an American football field. The patients were 60 to 78 years old.
In this crossover study, the patients were randomized to receive 40 g (about 200 calories) of dark chocolate (>85% cocoa) or milk chocolate (<35% cocoa).
For each type of chocolate, the patients had blood drawn early in the morning to analyze oxidative stress and other variables. An hour later, they did a treadmill walking test, and then half an hour later they were given the 40 g of chocolate. Two hours after eating the chocolate, they had more blood tests and a second treadmill test.
After eating dark chocolate, the patients walked, on average, almost 12 m (39 ft) farther and about 17 seconds longer than their distance and times obtained without eating chocolate. Eating milk chocolate did not improve walking times or distances.
“The different effect of dark and milk chocolate on walking autonomy supports the hypothesis that polyphenol content may be responsible for this effect, because dark chocolate is richer in polyphenol compared with milk chocolate,” the researchers write.
After the participants ate dark chocolate, their serum nitric-oxide levels increased, arterial endothelial function improved, and biochemical measures of oxidative stress decreased.
The findings are not transferable to clinical practice just yet, since it was a small study that lacked a placebo group, and the long-term effect on PAD from regularly indulging in a small piece of dark chocolate is unknown.
“Extremely Preliminary,” Beware of Extra Calories
“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 (AHA) spokesperson Dr Mark Creager (Brigham and Women’s Hospital and Harvard Medical School, Boston, MA) said in a statement. For example, after early promise, the antioxidants vitamin C and vitamin E did not turn out to improve cardiovascular health.
Moreover, chocolate is high in calories, sugar, and fat. A typical American chocolate bar provides 94 calories from sugar (24 g) and 8 g of saturated fat, according to statement from the AHA. The AHA recommends that daily sugar consumption should not be more than 150 calories (9 tsp) for men or 100 calories (6 tsp) for women, and saturated fat should not be more than 5% to 6% of daily calories. Cloves, dried peppermint, celery seed, capers, and hazelnuts are low in calories and fat and high in polyphenols.
The authors had no disclosures.
References
- Loffredo L, Perri L, Catasca E, et al. Dark chocolate acutely improves walking autonomy in patients with peripheral artery disease. J Am Heart Assoc 2014; DOI:10.1161/JAHA.114.001072. Available at: http://jaha.ahajournals.org.