How to Diet: Can Chocolate Protect your Heart and Brain?

“To improve a memory, consider chocolate,” ran the New York Times headline in October.

“A few squares of dark chocolate a day can reduce the risk of death from heart attack by almost 50 percent in some cases,” explained a recent WebMD article called “Health by Chocolate.”

In fact, small studies do suggest that the naturally occurring flavanols in cocoa beans may improve blood flow and memory and lower blood pressure. But it’s difficult, if not impossible, to get enough from eating chocolate.

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As for memory, in October, researchers at Columbia University reported that 19 healthy people aged 50 to 69 who were given a high level of cocoa flavanols (900 milligrams) every day for three months were quicker at recognizing visual patterns than 18 others who got a placebo. The flavanol takers were no better at remembering the patterns, though they did have increased activity in a part of the brain involved in memory.

But the first large study to test whether cocoa flavanols can lower the risk of heart attacks, strokes, memory loss, or any other illness is just getting under way.

“Cocoa flavanols look promising,” says JoAnn Manson, professor of medicine at Harvard Medical School.

“The next logical step is to move from the small randomized trials looking at mechanisms like changes in blood flow and blood pressure to testing whether cocoa flavanols can reduce the risk of clinical events—heart attacks, strokes, cardiovascular deaths.”

Manson is co-directing the new trial— the Cocoa Supplement and Multivitamins Outcomes Study (COSMOS)—which will give cocoa flavanols (750 mg a day) or a placebo to 18,000 women (aged 65 or older) and men (aged 60 or older) for four years. The trial is co-led by Howard Sesso, associate professor of medicine at Harvard Medical School. [Call 800-633- 6913 if you’re interested in participating.]

“We’ll also look at cognitive function, diabetes, physical performance, and other outcomes,” explains Manson.

But it’s not worth signing up so you can eat chocolate in the name of science.

“It’s not a randomized trial of chocolate or even dark chocolate,” notes Manson. “It’s a randomized trial of cocoa flavanols—bioactive plant-based nutrients with virtually no calories, sugar, or fat.”

Why can’t you get the same 750 mg of flavanols from chocolate?

“It would require an enormous amount,” says Manson, who is also chief of preventive medicine at Brigham and Women’s Hospital in Boston. “And for many forms of chocolate, it would be virtually impossible because the cocoa flavanols are destroyed in processing.”

To get 750 mg of flavanols a day, you’d have to eat nearly 1,000 calories’ worth of dark chocolate or thousands of calories of milk chocolate every day. A more reasonable source: an unsweetened cocoa powder you can mix into your coffee, milk, yogurt, hot cereal, or other food—that is, if the cocoa hasn’t been processed in a way that destroys flavanols.

“In COSMOS, we’ll be giving people cocoa flavanols that were protected from the time that they were harvested from cocoa beans,” says Manson. “They come in a capsule, which makes it possible to do a long-term placebo-controlled trial and not add a load of sugar, saturated fat, and calories to the diet.”

(The study is funded by Mars Symbioscience, a division of Mars, Inc., with partial support from the National Institutes of Health.)

“People have had so many misconceptions about the study,” says Manson. “They think we’re testing chocolate or that the trial is a signal that they should eat more chocolate. It isn’t.

“People can still eat chocolate for their enjoyment, but we don’t recommend that they eat more of it to get more flavanols.”

Bottom Line: It’s too soon to know whether cocoa flavanols protect the heart or brain. And don’t use them as an excuse to eat more chocolate.

Sources: Arch. Biochem. Biophys. 527: 90, 2012; Cochrane Database Syst. Rev. 8: CD008893, 2012; Nature Neurosci. 2014. doi:10.1038/nn.3850.

Other relevant links:

• Do flavanols help prevent heart disease? See: What to Eat: Chocolate and Cardiovascular Disease

• Can you eat milk chocolate to improve your circulation? See: What to Eat: Are Cocoa and Chocolate a Reliable Source of Flavanols?

• Not all flavanol supplements are equal. See: Are You Loco for Cocoa?

2 Replies to “How to Diet: Can Chocolate Protect your Heart and Brain?”

  1. Chocolate is my favorite midnight snack….I hope the test finds good reason to keep drinking it. I make my own from plain Cocoa powder & sugar, plus 2% milk: it helps me get to sleep!!!

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