March 26, 2007
Daily Dose of Cocoa Might Improve Blood Flow, Study Says
By JOHN FAUBER
Feeding chocolate to a bunch of middle-age, overweight people for weeks on end might not be as unhealthy as it seems.
The study is the latest in a growing number that link reduced heart disease risk to flavonoids in dark chocolate and other food and beverages, such as red wine, green tea and dark-colored fruits and vegetables.
"There are hundreds, if not thousands, of flavonoids in every plant substance we eat," said James Stein, director of preventive cardiology at the University of Wisconsin School of Medicine and Public Health. "This is a very hot area. This study confirms what other investigators have found."
Flavonoids have been found to relax blood vessels and thereby improve blood flow, inhibit platelets from sticking together in the blood, and have a beneficial antioxidant effect.
What still is not known is whether regularly eating dark chocolate, especially with its high sugar and fat content, eventually will lead to an unhealthy weight gain that would erase the beneficial effects of the flavonoids found in the cocoa.
Cocoa is one of the most concentrated sources of the flavonoids catechin and epicatechin.
Consuming foods such as dark chocolate and red wine can be a double-edged sword, Stein said.
"They shouldn't be considered health foods," he said. "They are treats and shouldn't be staples in the diet."
If they are used to replace a high-calorie food with little or no nutrition, such as soda, then it may be a beneficial, he said.
The study involved 39 people with an average age of 52 who, on average, were mildly obese.
The study had participants consuming a Hershey dark chocolate cocoa mix with sugar (230 calories); a Hershey mix that was artificially sweetened (45 calories); and a placebo mix made of sweetened whey powder (250 calories).
At the end of the study each person had consumed each preparation for six weeks, with four-week breaks between to allow each mixture's effects to dissipate.
The study, funded by Hershey and the U.S. Centers for Disease Control and Prevention, was presented this weekend at the American College of Cardiology meeting in New Orleans.
Doctors used ultrasound to measure blood flow in an artery in the arm, a test that corresponds well to heart disease risk.
The artificially sweetened cocoa mix was associated with about a 37% improvement in blood flow. The sugared cocoa was associated with a 23% improvement, suggesting that sugar interferes with the beneficial actions of flavonoids. The placebo mix resulted in a 12% reduction in blood flow.
"This tells you that it (cocoa) is cardio-protective," said lead author Valentine Njike, a physician and researcher at Yale University School of Medicine.
Njike said the research is the first to evaluate the effect of cocoa on blood flow over a period of weeks in overweight and obese people. He said there was no appreciable weight gain during the course of the study, although he acknowledged that weight gain can be a problem with dark chocolate containing a lot of fat and sugar.
The study's findings counter an old belief about nutrition, said Robert Rosenson, a professor of medicine at the University of Michigan Medical Center.
"Many people feel that in order to get health benefits, they have to eat foods that are unpalatable," said Rosenson, who was not a part of the study.
He noted that the biggest effect was found with the cocoa without sugar. And he said that other research indicates that milk chocolate does not have the benefits.
Rosenson also said that the beneficial blood flow effect of cocoa usually diminishes within six hours, meaning that it might have to be consumed several times a day to obtain a continuous improvement.
For that reason and because of the concern about calories, the ultimate answer eventually may come in the form of a so-called biopharmaceutical, a pill that contains concentrated amounts of the desired flavonoids and no fat or sugar, he said.
WHAT THE STUDY FOUND
-- Those who drank an artificially sweetened mix made with cocoa powder had a 37% improvement in blood flow.
-- Those who drank sugared cocoa had a 23% improvement.
-- Those who drank a placebo had a 12% reduction in blood flow.
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