A large study on the long-term effects of a cocoa flavanol supplement for the prevention of cardiovascular disease indicates promising signals that such flavanols could protect cardiovascular health.
The research, led by Howard Sesso, ScD, MPH, and JoAnn Manson, MD, DrPH, of Brigham and Women’s Hospital, involved the Cocoa Supplement and Multivitamin Outcomes Study (COSMOS).
While neither the cocoa flavanol supplement nor a multivitamin strongly reduced overall heart disease events, people who received the cocoa flavanol supplement had a 27% lower rate of heart death.
Key Findings
“Looking at the totality of evidence for both primary and secondary cardiovascular endpoints in COSMOS, we see promising signals that a cocoa flavanol supplement may reduce important cardiovascular events, including death from cardiovascular disease,” said Sesso.
“These findings merit further investigation to better understand the effects of cocoa flavanols on cardiovascular health.”
Previous smaller trials had found cardiovascular benefits of cocoa flavanols on blood pressure and blood vessel dilation.
The COSMOS trial provided the first opportunity to study whether a cocoa flavanol supplement might lead to longer-term reductions in clinical cardiovascular events and cancer.
The primary cardiovascular outcome for the cocoa flavanol intervention was a composite of total cardiovascular events, including heart attacks, stroke, coronary revascularization, cardiovascular death, carotid artery disease, peripheral artery surgery, and unstable angina.
More than 21,000 participants took daily capsules that contained either 500 mg of cocoa flavanols (donated by Mars Edge), a multivitamin tablet (donated by GSK Consumer Healthcare), or neither or both.
The study found that cocoa flavanols reduced total cardiovascular events by 10%, but this was not statistically significant.
However, several secondary analyses showed a potential benefit of cocoa flavanols on cardiovascular events.
Those receiving the cocoa flavanol supplement had a significant 27% reduction in death from cardiovascular disease.
When considering those who regularly took their study pills, a stronger 15% reduction in total cardiovascular events and a 39% reduction in death from cardiovascular disease were observed.
Next Steps
However, the authors note the promising results on cocoa flavanols and cardiovascular events need cautious interpretation and highlight the need for additional research.
A daily multivitamin had no significant effect on total or individual cardiovascular events.
The COSMOS trial ended after about 3.6 years, which was likely too short to detect whether the supplements could have affected cancer risk.
“Although our study suggests intriguing signals for cardiovascular protection with cocoa flavanols, any health benefits due to taking these supplements will need confirmation in a future trial,” said Manson.
The researchers encourage consumers to maintain a healthy, balanced diet, rich in natural food sources of flavanols, and to stay tuned as they further evaluate other important health outcomes in COSMOS.
If you care about heart health, please read studies about the DASH diet linked to a lower risk of heart failure, and calcium supplements may harm your heart health.
For more information about health, please see recent studies that olive oil may help you live longer, and Vitamin C linked to lower risk of heart failure.
The study was published in The American Journal of Clinical Nutrition.
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