Can cocoa prevent heart disease

Fred Hutch participates in largest-ever study to find out
Cocoa beans and chocolate
Photo by FeaturedPics

Leave it to scientists to find the best in chocolate.

Researchers hoping to determine whether cocoa flavanols can help reduce the risk of heart disease have designed a trial that won’t use actual chocolate, but rather pills packed with flavanols, the potent ingredients thought to be the effective agents. The flavanols will be extracted from the cocoa into a concentrated form.

“The cocoa flavanols will not taste like chocolate,” said Dr. Garnet Anderson, principal investigator of the Women’s Health Initiative (WHI) Clinical Coordinating Center at Fred Hutchinson Cancer Research Center and a co-investigator on the study. “Women will get the pills or a matching placebo. Because they won’t have a flavor, the women won’t know which they are on.”

The trial, named the Cocoa Supplement and Multivitamins Outcomes Study (COSMOS), will include 12,000 WHI study participants, and will look at the impact of flavanols – ingredients from cocoa – on heart disease. The idea is to see whether taking this specialized cocoa extract cuts down on heart attacks, strokes, and surgeries to open clogged arteries.

The pills will contain far more flavanols than cocoa-consuming women normally take in, even those who eat a lot of chocolate. “To eat enough chocolate to have the effects of these pills, you’d, unfortunately, gain a lot of weight,” said Anderson, who also directs the Fred Hutch Public Health Sciences Division.

The study, which will be led by researchers at Brigham and Women’s Hospital in Boston, will be funded by Mars, Inc., the makers of Dove Bars and M&Ms.

There have been hints over the years that cocoa might have health benefits. Some small clinical trials have shown that cocoa extracts can lower cholesterol and blood pressure. But so far, no one has shown that that translates to fewer heart attacks and strokes.

“There are a variety of studies of varying quality suggesting people who eat chocolate, particularly dark chocolate, may have better outcomes,” Anderson said. “This study will test whether flavanols can affect the rate of heart disease.”

Even if the study finds that flavanols don’t lower the risk of heart disease, that’s an important piece of information for American consumers, Anderson said.

The study will additionally look at multivitamin supplements in the same population of WHI participants and whether the multivitamin supplements reduce the risk of cancer. 

“Half of the U.S. adult population is taking supplements,” she explained. “If that many people are taking them, we should know what their health effects are – good or ill. Some recent studies have found that certain supplements not only didn’t have a positive effect, but also had negative effects.”

Of course, if the new study finds that the ingredients in cocoa can help prevent heart disease, that would be a bonus, Anderson said. “It would be an additional benefit on top of the pleasure we derive from eating chocolate.”

Study Overview

Participants to the Cocoa Supplement and Multivitamins Outcomes Study (COSMOS) will be randomized to the cocoa extract or placebo and at the same time to a multivitamin or placebo. Learn more »

Linda Carroll is a longtime health and science writer. She is coauthor of "The Concussion Crisis: Anatomy of a Silent Epidemic." 

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