THURSDAY, Jan. 12 (HealthDay News) -- In smokers, dark chocolate lowers oxidative stress and has an inhibitory effect on platelet function, according to a study published in the January issue of the Journal of Thrombosis and Haemostasis.
Roberto Carnevale, Ph.D., from Sapienza University in Rome, and colleagues conducted a single-blind crossover study involving 20 smokers and 20 healthy individuals to evaluate whether dark chocolate inhibits the formation of reactive oxygen species (ROS) in platelets or affects platelet activation. Subjects were given 40 g of dark chocolate, containing >85 percent cocoa, or milk chocolate, containing <35 percent cocoa.
The investigators found that dark chocolate significantly decreased the activation of platelet ROS (−48 percent), 8-iso-prostaglandin F2α (8-iso-PGF2α) (−10 percent), and nicotinamide adenine dinucleotide phosphate-oxidase 2 (NOX2) activation (−22 percent) in smokers, but platelet variables were not affected in healthy subjects. Milk chocolate did not elicit any significant effects in either group. Dark chocolate similarly increased serum epicatechin in smokers and healthy subjects. Reduced platelet recruitment, platelet 8-iso-PGF2α and ROS formation, and NOX2 activation were induced in platelets from smokers, following platelet incubation with catechin.
"In conclusion, the present study demonstrates that dark chocolate down-regulates platelet ROS generated by NOX2 and ultimately inhibits platelet activation via inhibition of platelet 8-iso-PGF2α. Such an effect seems to be related to the antioxidant property of its polyphenol content, as platelet incubation with epicatechin and catechin reproduced the findings achieved in vivo," the authors write.