Chocolate Has Antithrombotic Effects Similar to Aspirin

Martha Kerr

November 17, 2006

November 17, 2006 (Chicago) -- Subjects enrolled in the Genetic Study of Aspirin Responsiveness (GeneSTAR) inadvertently helped Johns Hopkins University researchers measure chocolate's inhibition of platelet function and show that eating chocolate slows clotting time. The findings may explain how chocolate and cocoa-containing foods exert a cardioprotective effect.

Subjects in the GeneSTAR study were instructed to exercise, stop smoking, and avoid food and drink known to contain flavenoids, which interfere with platelet activity. These foods include grapefruit, caffeine-containing substances, wine, and chocolate and other cocoa-containing substances.

A group of 139 healthy individuals did not eliminate chocolate from their diet.

Senior investigator Nauder Faraday, MD, associate professor of anesthesia and critical care medicine at Johns Hopkins University in Baltimore, Maryland, told Medscape that "chocolate was just one of those things this group couldn't give up."

The subjects were ejected from GeneSTAR proper and were not randomized in the aspirin assessment phase of the study. But Dr. Faraday and colleagues took advantage of the subjects' noncompliance to assess chocolate's previously demonstrated role in cardiovascular risk reduction, using the same platelet function analyzer test employed in the GeneSTAR study.

The investigators measured agonist-induced platelet activation in the presence of shear and calculated time to closure in the system by a platelet plug. Platelet activation was also assessed on urinary excretion.

Chocolate consumption caused a significant increase in time to closure, but remained within the normal range, the investigators announced here this week at the American Heart Association 2006 Scientific Sessions.

"Chocolate, even in small amounts, was an independent factor in inhibition of platelet activation," Dr. Naraday said. It extended closure time, regardless of age, sex, smoking status, body mass index, systolic blood pressure, total cholesterol level, fibrinogen levels, or von Willebrand factor.

"The magnitude of the effect was quite small," Dr. Naraday emphasized. Chocolate had the same type of effect as aspirin, but by a factor of 5 to 10 times less, according to the assay used in the GeneSTAR study, he said.

Elliott Antman, MD, professor of medicine at Harvard University in Cambridge, Masssachusetts, told Medscape that he found the results intriguing. "It might help explain the tremendous variability among patients to platelet inhibition, particularly as seen in response to aspirin."

Dr. Naraday pointed out that "any time you shift the balance away from thrombosis, you set up a situation with the potential for increased bleeding time and other risks, but I don't think this is a big problem with eating chocolate!"

Dr. Faraday's study is funded by the National Heart, Lung, and Blood Institute of the National Institutes of Health. Dr. Antman reports no relevant financial relationships.

AHA Scientific Sessions 2006: Abstract 4101. Presented November 14, 2006.

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