Could Cocoa Flavanols Improve Heart Health?

JoAnn E. Manson, MD, DrPH


February 01, 2016

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Hello. This is Dr JoAnn Manson, professor of medicine at Harvard Medical School of Brigham and Women's Hospital.

With February being Heart Health Month and with Valentine's Day just around the corner, I thought it might be appropriate to talk with you about the cocoa flavanols and the emerging and growing evidence that they can confer heart health benefits.

The cocoa flavanols are naturally occurring, plant-derived bioactives from the cocoa bean. There are other sources of flavonoids, including fruits such as berries, apples, and pears, as well as other sources such as tea and wine; however, the cocoa flavanols may have special properties.

There are now several small-scale randomized clinical trials demonstrating that the cocoa flavanols in amounts ranging between 400 and 900 mg/day may favorably affect several mechanisms and pathways that are related to cardiovascular disease prevention. And this includes effects on improving flow-mediated vasodilatation, lowering blood pressure, improving glucose tolerance, decreasing inflammation, and even slowing cognitive decline and age-related memory loss.[1,2,3,4,5] So that's the good news.

However, we don't yet have a large-scale, randomized clinical trial demonstrating that the cocoa flavanols can reduce the risk for clinical events, such as cutting rates of heart attacks and strokes. We're now doing such a trial in 18,000 men and women around the country. This is called the COSMOS Trial, the cocoa supplement and multivitamin outcome study that is testing 600 mg/day of the cocoa flavanols.

This is a public-private partnership with Mars Symbioscience and with recruitment from National Institutes of Health (NIH)-sponsored studies such as the Women's Health Initiative, as well as some of the ancillary studies that are sponsored by the NIH.

While waiting for the results of this trial, which may take another 4 years, it's important to understand that chocolate and cocoa flavanols are not synonymous and that chocolate actually provides highly variable amounts of the cocoa flavanols; it will depend on the harvesting and processing of the cocoa. And there are many forms of chocolate that are high in sugar, saturated fat, and calories and provide minimal—if any—cocoa flavanols.

So, it's important to keep in mind that chocolate itself is really not a superfood for heart health, but it's a wonderful treat and can certainly be enjoyed in moderation.

If you're looking for a cocoa product that is more likely to confer heart benefits, then look at the ingredient list and look for cocoa or cacao as the first ingredient, rather than sugar.

Stay tuned for the results of COSMOS and other research studies related to the cocoa flavanols. In the meantime, happy Valentine's Day, and enjoy some chocolate in moderation.

Thanks so much for your attention. This is JoAnn Manson.


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