Eating dark chocolate may be good for the heart

Consumption of dark chocolate may reduce cardiovascular and thromboembolic disease, according to a study presented at the 19th Congress of the International Society on Thrombosis and Haemostasis. The cocoa fraction of chocolate contains flavonoids, which also are found in red wine, fruit, and vegetables. Flavonoids reduce platelet activation and produce a cardioprotective mechanism called the French paradox (ie, lower than expected rate of heart disease in a population that consumes a diet high in saturated fat). Dark chocolate has a higher flavonoid concentration than milk chocolate or white chocolate.

Researchers at the University of Dundee, Nethergate, Dundee, Scotland, studied the effects of chocolate consumption on ex vivo platelet activity in healthy volunteers. Thirty participants were assigned randomly to receive 100 g of white chocolate, milk chocolate, or dark chocolate. Blood samples were taken before chocolate consumption and four hours after chocolate consumption. Three measures of platelet function--platelet rich plasma (PRP) aggregation, whole blood platelet aggregation, and platelet nitric oxide (NO) production--were taken.

White chocolate was found to have no effect on platelet function. Milk chocolate demonstrated a trend toward reduced platelet function, but most results were not significant, and milk chocolate had no effect on NO production. Dark chocolate reduced collagen-stimulated PRP aggregation, collagen-stimulated whole blood platelet aggregation, and spontaneous unstimulated whole blood platelet aggregation. Dark chocolate also was associated with a reduction in plasma NO before and after aggregation, although this was only significant in the postaggregation data set.

G Kennedy et al, "Dark chocolate inhibits platelet aggregation in healthy volunteers," (Abstract) Journal of Thrombosis and Haemostasis no 1 suppl (July 2003) abstract 2002, Blackwell Publishing, http://www.blackwellpublishing.com/isth2003/abstract.asp?id=10185 (accessed 5 Aug 2003).

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