Heart Health


There have been several studies to examine if and how the flavanols found in Cocoa could have a positive effect on the cardiovascular system. However, the first large-scale study found insignificant results under one analysis, but more promising results under another, concluding that more research was required to understand how health benefits may be derived.

Part of the reason behind a lack of understanding of the effects of Cocoa extract is that the studies to date have all been conducted on a relatively small scale, so researchers need more well-conducted, peer-reviewed studies on a larger scale.

The researchers, under the name of COSMOS (COcoa Supplements and Multivitamin Outcomes Study), followed the trial participants over a median period of 3.6 years to document what negative cardiovascular events they encountered. 

The trial covered the use of both multivitamins and Cocoa extract. In this article, we have focused on the results related to the Cocoa extract.

There are several active ingredients in Cocoa, but it is the presence of methylxanthines in Cocoa that enhances the beneficial vascular effects commonly attributed to the ingestion of cocoa flavanols.

Experimental and clinical studies testing the consumption of Cocoa products and Cocoa flavanols have noted potential benefits on platelet activation, endothelium-dependent vasodilation, inflammation, blood pressure, and insulin resistance, which may translate into important cardiovascular benefits.

Results – COSMOS Trial

A total of 21,442 people with an average age of 72.1 years ( 12,666 women aged at least 65 years and 8,776 men aged at least 60 years) were included in a randomised trial. About half of these participated with the Cocoa extract.

During the trial, 410 out of 10,719 participants taking Cocoa extract and 456 out of 10,723 participants taking placebo had confirmed total cardiovascular events – including heart attack, stroke, coronary revascularization, death caused by cardiovascular disease, unstable angina requiring hospitalization, carotid artery surgery and peripheral artery surgery. This translates to a modest 10% reduction in cardiovascular events for those taking Cocoa extract, but it was not statistically significant.

Results – COSMOS Trial

However, when the researchers conducted further analysis, they found that comparing participants who remained compliant with the active Cocoa extract and placebo groups, supplementing the Cocoa extract did have a more significant effect, reducing cardiovascular events by 15%. 

The same Cocoa extract supplementation additionally reduced deaths from cardiovascular events by 27%. The researchers also looked for benefits in reducing deaths from cancer-related diseases but found no effects.

The study indicates that there is some truth behind the claims about the benefits of Cocoa extract supplementation but that more studies are needed.

To carry out the trial, the US researchers created four test groups:

  • Cocoa supplement ((500 mg flavanols/day) and a multivitamin
  • Cocoa supplement and placebo vitamin
  • An active multivitamin with a placebo
  • two placebos

The report findings can be viewed here

Citation: Howard D Sesso, JoAnn E Manson, Aaron K Aragaki, Pamela M Rist, Lisa G Johnson, Georgina Friedenberg, Trisha Copeland, Allison Clar, Samia Mora, M Vinayaga Moorthy, Ara Sarkissian, William R Carrick, Garnet L Anderson, COSMOS Research Group, Effect of cocoa flavanol supplementation for the prevention of cardiovascular disease events: the COcoa Supplement and Multivitamin Outcomes Study (COSMOS) randomized clinical trial, The American Journal of Clinical Nutrition, Volume 115, Issue 6, June 2022, Pages 1490–1500, https://doi.org/10.1093/ajcn/nqac055

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    Nick Baskett is the editor in Chief at Bartalks. He holds a diploma from the Financial Times as a Non Executive Director and works as a consultant across multiple industries. Nick has owned multiple businesses, including an award-winning restaurant and coffee shop in North Macedonia.

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