Extra Rich Cocoa May Improve Heart Function in Smokers
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Confirmed smokers might improve their heart health if they traded a “cuppa joe” for a cup of cocoa, according to researcher here. But the best advice to smokers remains the proven message: kick the habit.
A special very dark chocolate cocoa increased plasma concentrations of nitric oxide and improved flow mediated dilation response by almost 50% in a small group of smokers recruited for the study, said Malte Kelm, M.D. of the Heinrich Heine University here.
This finding, which was published online by The Journal of the American College of Cardiology, is one of several studies that suggest a cardiovascular benefit for flavonol-rich dark chocolate products.
However, ordinary cocoa drinks or hot chocolate are unlikely to have the same effect, as the drink used in the study was specially processed to retain higher levels of flavonol than other commercially available products, Dr. Kelm said.
Nitric oxide is a short-lived signaling molecule essential to vascular homeostasis, including vasodilatation, the researchers said. Circulating nitric oxide is thought to be a “storage pool” of this important molecule, which can compensate for local nitric oxide deficits and restore vascular function where needed.
Previous research has suggested that the cardiovascular benefits of flavonols, which are also found in fruits and vegetables, are partly due to their ability to increase nitric oxide synthesis, the researchers noted.
The current study focused on smokers because they tend to have lower levels of circulating nitric oxide and poorer vascular endothelial function than non-smokers.
The randomized, double-blind crossover study tested the effects of a high-flavanol and low-flavonol cocoa drink in 11 smokers. The high-flavonol drink contained 176 to 185 mg of flavonols, and the low-flavonol drink contained less than 11 mg.
The researchers measured levels of circulating nitric oxide and flow mediated dilation of the brachial artery in the smokers at baseline and two hours after drinking the cocoa.
The average level of circulating nitric oxide increased from a baseline of 20 nmols/liter to nearly 30 nmol/l two hours after participants drank the high-flavonol cocoa (P<.001). No increase was associated with the low-flavonol drink.
Flow mediated dilation increased from an average of 4.2% at baseline to nearly 7% two hours after drinking the high-flavanol cocoa (P<.001). Again, no significant increase was associated with the low-flavanol drink.
The flavonol-related improvement of endothelial function could be reversed by infusion of L-NG-monomethyl-arginine, an inhibitor of nitric acid synthase, consistent with the hypothesis that the mechanism of action of flavonol rich food involves an increase in nitric acid synthase activity.
“While the long-term benefits of such improvements remain to be established, we believe that one exciting outcome of this study is the demonstration that flavonol-rich cocoa can significantly improve an important marker of cardiovascular health in a population with an established cardiovascular risk factor,” Dr. Kelm said.
“This raises the possibility that a potential new agent for the prevention and/or treatment of cardiovascular disease may emerge from additional research,” he added.
Source: Journal of the American College of Cardiology
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