Dark Chocolate: Good for the Heart, Loaded With Flavonoids
Reviewed By Brunilda Nazario, MD, MD on Tuesday, June 01, 2004, WebMD Medical News
Here's news that's hard not to like. Eating a small, 1.6-ounce bar of dark chocolate every day is good for you. Very good for you, find Mary Engler, PhD, RN, of the University of California, San Francisco, and colleagues. Now here is a medical experiment you would love to volunteer for. Engler's team divided 21 healthy adults into two groups. One group got a Dove Dark Chocolate bar every day for two weeks. Like other dark chocolate bars with high-cocoa content, this one is loaded with something called epicatechin. Epicatechin is a particularly active member of a group of compounds called plant flavonoids. Flavonoids keep cholesterol from gathering in blood vessels, reduce the risk of blood clots, and slow down the immune responses that lead to clogged arteries.
The second group that didn't get Dove bars wasn't totally left out. They, too, got dark chocolate bars. But their treats had the flavonoids taken out. All subjects underwent high-tech evaluation of how well the blood vessels dilate and relax - an indictor of healthy blood vessel function. Blood vessel stiffness indicates diseased vessels and possible atherosclerosis. Those who got the full-flavonoid chocolate did significantly better. Why? Blood tests showed that high levels of epicatechin were coursing through their arteries. "This is the longest clinical trial to date to show improvement in blood vessel function from consuming flavonoid-rich dark chocolate daily over an extended period of time," Engler says in a news release. "It is likely that the elevated blood levels of epicatechin triggered the release of active substances that ... increase blood flow in the artery. Better blood flow is good for your heart."
Why Dark Chocolate Is Different
Not all chocolate is created equal. Dark chocolate contains a lot more cocoa than other forms of chocolate. And standard chocolate manufacturing destroys up to half of the flavonoids. But chocolate companies have now learned to make dark chocolate that keeps up to 95% of its flavonoids. Sure, this seems like a scam. Can't you get more and better flavonoids from other foods? Surprisingly, the answer is "not really." Engler says that dark chocolate contains more flavonoids than any other food - including green tea, black tea, red wine, and blueberries. "Many people don't realize that chocolate is plant-derived, as are the fruits and vegetables recommended for a healthy heart," Engler says.
While a little dark chocolate is good, a lot is not better. Chocolate still is loaded with calories. If you're going to eat more chocolate, you'll have to cut back somewhere else. And remember that a balanced diet - and plenty of exercise - is still the key to heart health.Engler's study was funded by the University of California, San Francisco, School of Nursing. The American Cocoa Research Institute, a nonprofit group funded by the chocolate industry, provided the chocolate used in the study. The findings appear in the June issue of the Journal of the American College of Nutrition. Engler previously reported the findings at the 2002 Scientific Sessions of the American Heart Association and at the Experimental Biology 2003 meeting.
SOURCES: Engler, M.B. Journal of the American College of Nutrition, June 2004; vol 23: pp 197-204. News release, University of California, San Francisco.