Published online 17 July 2000 | Nature | doi:10.1038/news000720-4


Chocoholics take note

Xavier Bosch finds that a cup of cocoa might give you more than a good night's sleep.

Chocolate: good for your heart as well as the taste buds.Chocolate: good for your heart as well as the taste buds.© Photodisc

Chocolatecould be good for your heart, a report in the American Journal of Clinical Nutrition suggests. Chocolate contains flavonoids, a group of chemicals found in many plant foods such as red wine, tea, onions and parsley, which have received a lot of attention recently for their beneficial influence on cardiovascular health.

There are two ways in which flavonoids may protect the heart. They seem to lower the amount of 'low-density lipoproteins' (LDL), or so-called 'bad cholesterol', in the blood. And they may stop blood platelets clumping together -- a process that plays a principal role in atherosclerosis.

Previous studies revealed that cocoa-powder extract lowers LDL levels. Now, Carl Keen from the Department of Nutrition, University of California, Davis, and colleagues find that cocoa also inhibits platelet activation -- the first step in clot formation -- and that, like asprin, it thins the blood, slowing coagulation.

The researchers took blood from ten healthy subjects just before, and two and six hours after they had drunk a strong beverage made from cocoa. Ten subjects were given caffeine-containing drinks and ten water, as controls.

Keen's group counted the number of platelet microparticles -- tiny tubes formed during platelet activation which seem to encourage coagulation. Two and six hours after cocoa consumption, platelet activation was lower and fewer microparticles had formed than normal. Moreover, blood from these subjects took longer to form a clot than blood from control subjects.

"The highly enriched flavonoid composition of the cocoa beverage used in the study may have contributed to the inhibition of platelet activity after its consumption," says Keen. "Our work supports the concept that the chronic consumption of cocoa may be associated with an improved cardiovascular health; yet some positive effects can even be observed on an acute basis." He adds: "Cocoa and presumably other forms of chocolate can be part of a healthy diet".

But Tissa Kappagoda, director of the Preventive Cardiology Unit at the University of California, Davis, warns: "[cocoa] contains a significant proportion of fat calories and it may not be the best option for patients with coronary atherosclerosis".

Ramón Segura, Professor of Human Physiology and Nutrition at the University of Barcelona, Spain, disagrees: "Cocoa and dark chocolate may be cardioprotective". Fat-wise, chocolate contains short-chain saturated fatty acids and oleic acid (also found in olive oil), which are difficult to oxidize, so its contribution to atherosclerosis is minimal.

"Apart from diabetics, it may be healthy that people incorporate 15 to 20 grams of dark chocolate into their daily diet," Segura suggests.

Interestingly, this work was primarily supported by M&M Mars Incorporated, a multi-national company that manufactures, among other things, chocolate. The health benefits of chocolate were initially investigated by Japanese scientists at the Meiji Company -- a competitor of M&M Mars. Meiji already markets a flavonoids-enriched chocolate in Japan. 

  • References

    1. Rein,D. et al. Cocoa inhibits platelet activation and function. American Journal of Clinical Nutrition 72, 30 - 35 2000. | PubMed | ISI | ChemPort |