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Can Cocoa Extract Reduce Cardiovascular Disease?

Am Journal of Clinical Nutrition logo

We know that chocolate is the way to many people’s hearts. Now a study from The American Journal of Clinical Nutrition shows that a cocoa flavanol extract may offer protection against cardiovascular events. Flavanols are nutrient-rich compounds found in several plant foods, including cocoa, purple and red grapes, blueberries, and white, black, and green tea.

Study Results

Participants in the treatment group were given a cocoa extract supplement (500 mg/d cocoa flavanols, including 80 mg epicatechins) and a multivitamin to determine the supplements’ effectiveness in preventing cardiovascular disease and cancer. None of the subjects had a myocardial infarction, stroke, and/or were recently diagnosed with cancer (except non-melanoma skin cancer) within the past 2 years. Neither supplement was shown to significantly lower the number of cardiovascular events, but those taking the cocoa flavanol supplement had a 27 percent reduced risk of cardiovascular death, a pre-specified secondary endpoint. Researchers also reported a 10 percent decrease in total cardiovascular events, but that was deemed not statistically significant. There was no effect on cancer prevention with the cocoa supplement.

More Study Details

Known as the Cocoa Supplement and Multivitamin Outcomes Study (COSMOS), the study was conducted by a team of researchers from the Division of Preventive Medicine at Brigham and Women’s Hospital. The large-scale trial involved more than 21,000 participants and was randomized, double-blind, and placebo-controlled.

“COSMOS was unique to test cocoa extract, rather than just cocoa flavanols, against a placebo control. The 500 mg/day cocoa flavanols in COSMOS substantially exceeds the mean intake reported in Europe of 105 mg/day (ranging from 84 mg/day [Sweden] to 138 mg/day [Spain]) and aligns with amounts tested in short-term trials. Further, the COSMOS cocoa extract supplement avoided the perils of food-based cocoa interventions highly susceptible to variation in flavanol, theobromine, and other bioactive content.” 


Cocoa extract supplementation did not significantly reduce total cardiovascular events among older adults but reduced CVD death by 27%. Potential reductions in total cardiovascular events were supported in per-protocol analyses. Additional research is warranted to clarify whether cocoa extract may reduce clinical cardiovascular events.



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