Cocoa May Cut Blood Pressure

Study Tracked Eating Habits of Elderly Men

Medically Reviewed by Louise Chang, MD on February 27, 2006
From the WebMD Archives

Feb. 27, 2006 -- Cocoa might help curb blood pressure and lower death risk, new research shows.

Brian Buijsse, MSc, and colleagues report the news in the Archives of Internal Medicine. They studied 470 elderly men for 15 years, tracking the men's cocoa consumption, including chocolate.

Cocoa intake was tied to lower blood pressure and reduced death risk, the study shows. Natural compounds in cocoa called flavanols may be the reason, write Buijsse and colleagues.

However, it's "much too early to conclude that cocoa foods are good for cardiovascular health," Buijsse tells WebMD in an email.

Buijsse works in the Netherlands' Center for Nutrition and Health, which is part of the National Institute for Public Health and the Environment.

Tracking Cocoa Consumption

Participants were 65-84 years old when the study started in 1985. They were interviewed for an hour in their homes about the foods they ate.

Follow-up interviews were done five and 10 years later. All interviews were done in the presence of whoever prepared the men's foods, if the men didn't cook for themselves.

The researchers honed in on 24 foods that contain cocoa, including chocolate cookies, chocolate bars, chocolate pudding, and cocoa drinks. Then, they calculated those foods' cocoa content.

How Much Cocoa Did They Eat?

Here's a look at cocoa consumption in the study:

  • Average daily intake: 2.11 grams.
  • A third of the group didn't consume any cocoa when the study started.
  • Top cocoa consumption was more than 4 grams per day.
  • Most popular sources: Plain chocolate and chocolate bars.

Cocoa eaters were more likely to drink alcohol, eat nuts and seeds, and consume low- or medium-fat dairy foods, sugary confections, cookies, and savory foods.

The researchers didn't ask anyone to change their diets. Instead, they observed the men's cocoa consumption, blood pressure, and deaths.

Key Finding

"The key message is that our study suggests that using low amounts of cocoa foods on a daily basis, equal to about 10 grams of dark chocolate, may lower blood pressure and CVD [cardiovascular] death," Buijsse tells WebMD.

He calls for more studies, including some that directly test cocoa's health effects by assigning people to consume cocoa.

"Although there have been a few small intervention studies published, the amount of chocolate in these studies was huge -- in most cases 100 grams per day -- and the follow-up duration was quite short (a few weeks)," Buijsse says.

"These studies have clearly shown that cocoa lowers blood pressure and improves endothelial function. Now it is time to study whether there is a 'threshold' in the dose of chocolate. So, intervention studies that use lower amounts of dark chocolate or cocoa drink with duration longer than a few weeks are interesting," he continues. Endothelial function is the working of blood vessels' inner lining.

Stripped of Helpful Compounds?

"Of course, we need to test whether the cocoa flavanols are responsible," Buijsse says "A recently published study indeed indicates that they are. This needs to be confirmed."

His study tracked cocoa, not flavanols. That may be a weakness in the study, says Norman Hollenberg, MD, PhD, who recently published a different study on cocoa and blood pressure.

Hollenberg's study, published in Proceedings of the National Academy of Sciences, was funded by the candy company Mars Inc., which is developing flavanol-rich cocoa products.

Cocoa is usually processed to remove bitterness. "Unfortunately, the bitterness is the flavanoids," Hollenberg tells WebMD. Flavanols are a type of flavanoid.

Researcher's View

"I am aware that during the production process of chocolate (especially alkalization and roasting of the cocoa beans), a part of the flavanols is broken down," Buijsse says. "This may be true to some extent, but commercially available cocoa foods still contain flavanols," he says.

"Although the flavanol content of commercially available cocoa foods is lower than that used in certain intervention studies, our results suggest that these foods may still exert an effect on cardiovascular health," Buijsse continues.

Even so, there's good reason not to go overboard with cocoa and chocolate.

"Chocolate contains loads of calories because of the sugar and fat in it," Buijsse writes. "If people eat a lot of chocolate, they inevitably gain weight. And having a high body weight is a major risk factor for high blood pressure and CVD."

Remaining Questions

The Dutch study shows "evidence of protection, but we don't know how much chocolate produces how much protection, and whether a large amount of chocolate would produce even more protection. We just don't know," Hollenberg says.

Like Buijsse, Hollenberg mentions a need for interventional studies.

Such studies cost "easily tens of millions and commonly hundreds of millions of dollars, and they take years to do, and you can only do a limited number of them," Hollenberg says. "So we use evidence from observational studies of this sort to build our courage. And so we are still building our courage."

Show Sources

SOURCES: Buijsse, B. Archives of Internal Medicine, Feb. 27, 2006; vol 166: pp 411-417. Brian Buijsse, MSc, Center for Nutrition and Health, National Institute for Public Health and the Environment, Bilthoven, the Netherlands. WebMD Medical News: "Why Cocoa May Help Heart Health." Norman Hollenberg, MD, PhD, professor of medicine, Harvard Medical School. News release, JAMA/Archives.

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