Cocoa Flavanols Supplement Lowers Risk of Cardiovascular Death, Study Finds

JoAnn Manson, MD, DrPH

Data from a large-scale trial conducted by investigators from the Division of Preventive Medicine at Brigham and Women’s Hospital suggests long-term use of a cocoa flavanol supplement was associated with a 27% reduction in risk of cardiovascular death.

The Cocoa Supplement and Multivitamin Outcomes Study (COSMOS) trial, results of the study suggest use of a 500 mg cocoa flavanol was associated with a statistically significant 27% reduction in cardiovascular death and a nonsignificant 10% reduction in total cardiovascular events over a follow-up period lasting 3.6 years.

“Previous studies have suggested health benefits of flavanols — compounds in several plant-based foods including cocoa, tea, grapes, and berries,” said JoAnn Manson, MD, DrPH, both of the Division of Preventive Medicine at Brigham and Women’s Hospital, in a statement. “COSMOS was not a chocolate trial — rather, it’s a rigorous trial of a cocoa extract supplement that contains levels of cocoa flavanols that a person could never realistically consume from chocolate without adding excessive calories, fat, and sugar to their diet.”

A randomized, double-blind, placebo-controlled, 2x2 factorial trial, COSMOS was created with the intent of assessing whether a use of a twice-daily nutritional supplement totaling 500 mg/d of cocoa flavanols could reduce the risk of cardiovascular disease and cancer in adult patients. Enrolling patients from the Women’s Health Initiative Extension Study and Brigham and Women’s Hospital, investigators recruited a cohort 21,442 adult patients from June 2015-March 2018 without a history of cardiovascular disease or cancer for inclusion in their trial.

Patients included in the trial were randomized to the cocoa extract supplement or a multivitamin placebo. The primary outcome of interest for the trial was a composite of incident myocardial infarction, stroke, coronary revascularization, cardiovascular mortality, carotid artery surgery, peripheral artery surgery, and unstable angina requiring hospitalization. The trial also included 14 secondary outcomes and 4 other outcomes that were mostly related to subtypes of cardiovascular disease or cancer.

The overall patient cohort had a mean age of 72.1 (SD, 6.6) years and 77,331 total person-years of follow-up. Investigators pointed out women were older than men, but sociodemographic, medical, and lifestyle factors at baseline were similar between the cocoa flavanol supplement arm and the placebo arm of the trial.

Over a follow-up period lasting a median of 3.6 years, a total of 410 participants receiving the cocoa supplement and 456 receiving placebo (HR, 0.90 [95% CI, 0.78-1.02]; P=.11). When assessing secondary endpoints, results suggested patients who received the cocoa flavanol supplement were at a lower risk of cardiovascular death (HR, 0.73 [95% CI, 0.54-0.98]), myocardial infarction (HR, 0.87 [95% CI, 0.66-1.16), stroke (HR, 0.91 [95% CI, 0.70-1.17]), coronary revascularization (HR, 0.95 [95% CI, 0.77-1.17), and all-cause mortality (HR, 0.89 [95% CI, 0.77-1.03]).

“When we look at the totality of evidence for both the 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,” added Howard Sesso, ScD, MPH. “These findings merit further investigation to better understand the effects of cocoa flavanols on cardiovascular health.”

This study, “Effect of cocoa flavanol supplementation for prevention of cardiovascular disease events: The COSMOS randomized clinical trial,” was published in The American Journal of Clinical Nutrition.