Dark Chocolate May Cut High Blood Pressure

Researchers Say Flavonoids in Dark Chocolate May Be the Reason for Blood Pressure Improvement

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July 18, 2005 -- Taming high blood pressure could be downright delicious. Dark chocolate might help fight high blood pressure, new research shows.

The benefit could stem from flavonoids, write the researchers. Flavonoids are natural antioxidants found in chocolate, tea, red wine, and many fruits and vegetables.

But don't go overboard. Subjects only ate a little bit of dark chocolate. They cut other calories to avoid weight gain.

The findings appear in Hypertension's August issue.

High Blood Pressure Is Common

Nearly one in three U.S. adults has high blood pressure, but a third of them don't know it, says the American Heart Association.

High blood pressure is a major health danger. It raises the risk of heart attack, stroke, heart failure, and kidney failure.

A quick, noninvasive test can check blood pressure.

Chocolate Study

The study included 10 men and 10 women with high blood pressure that had never been treated. They were recruited from a clinic at Italy's Università di L'Aquila.

Subjects were about 43 years old, on average. To qualify, they needed systolic blood pressure (the first number of a blood pressure reading) of 140-159 or diastolic blood pressure (the second number) of 90-99.

Participants didn't have other health problems. They also didn't smoke or drink alcohol.

Eating Chocolate for Science's Sake

The study wasn't a chocolate free-for-all. The researchers drew up a schedule detailing the type and amount.

First, chocolate was totally forbidden for a week. Next, subjects were given a daily bar (about 3.5 ounces) of dark or white chocolate for another week.

Then, chocolate was banned for another week. Finally, subjects tried whichever bar they hadn't already eaten for a week.

Meanwhile, they wore mobile blood pressure monitors 24 hours a day.

Subjects were also told to maintain their normal activity level and to budget their diet for chocolate's calories.

Study's Results

The researchers took before-and-after blood pressure readings. They also checked levels of LDL "bad" cholesterol and insulin, a hormone that controls blood sugar.

With dark chocolate, 24-hour systolic blood pressure dropped 12 points; diastolic blood pressure dipped 8.5 points.


Insulin sensitivity and LDL cholesterol also improved with dark chocolate.

No benefits were seen with white chocolate.

Dark Chocolate Stood Out

White chocolate was the perfect comparison food, states researcher Jeffrey Blumberg, PhD, in a news release.

White chocolate doesn't contain any flavonoids. But it has all the other ingredients and calories of dark chocolate, says Blumberg.

"It's important to note that the dark chocolate we used had a high level of flavonoids, giving it a slightly bittersweet taste," he says.

"Most Americans eat milk chocolate, which has a low amount of these compounds," continues Blumberg.

Milk chocolate wasn't tested in the study.

Blumberg is a senior scientist, associate director, and chief of the Antioxidants Research Laboratory at the Jean Mayer USDA Human Nutrition Research Center on Aging. The Center is located at Tufts University.

More Work Ahead

The study was small and the findings need to be confirmed, write Blumberg and colleagues.

They didn't compare dark chocolate to other flavonoid-rich fare.

The study doesn't suggest dark chocolate as a replacement for exercise, a healthy diet, and (for some people), medications to control blood pressure.

"Caution is always warranted when considering dietary recommendations for foods high in fat and calories, especially for [heart] disease," write the researchers.

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SOURCES: Grassi, D. Hypertension, August 2005; vol 46. American Heart Association: "High Blood Pressure." News release, American Heart Association.

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