Web edition: August 10, 2005
You don't have to like Willy Wonka to wish you had your own chocolate factory. Americans consume about 1.5 million metric tons of chocolate confectionery products each year, and they spend nearly $10 billion to do so.
Perhaps that's not enough. Chocolate manufacturers seem increasingly to be aiming at a new market: health foods. Some new and soon-to-be-released chocolate products tout the fact that they are rich in flavonoids or in cocoa, which usually contains those potentially heart-healthy plant compounds.
A new study in Italy suggests that consuming flavonoid-rich dark chocolate instead of flavonoid-free white chocolate could not only lower blood pressure and cholesterolbenefits suggested by some prior studiesbut also improve the body's processing of sugar. That, in theory, could guard against diabetes. Is dark chocolate emerging as a health food?
No, researchers maintain. "I'm not suggesting that dark chocolate is now some therapeutic medicine," says Jeffrey B. Blumberg of Tufts University, who collaborated on the Italian study. Nevertheless, he says, the new finding suggests that specific flavonoids have beneficial effects on several measures of health.
"Perhaps," says Claudio Ferri, the leader of the new study, "a little bit of cocoa per day can be useful." But he's quick to add that most chocolate products are loaded with calories, so adding them to what a person already eats daily would add pounds. "The potential benefits will be surely bypassed and exceeded by excessive weight gain," says Ferri, an internist at the University of L'Aquila.
Dark chocolates, especially those made with minimal processing, may be better for you than alternative indulgences (see Chocolate-Science News and Chocolate Hearts). They tend to contain more flavonoids, and somewhat less saturated fat, than does milk chocolate. Cocoa powder and baking chocolate usually contain even more flavonoids than dark chocolate does. White chocolate typically has none.
Ferri and his colleagues tested a diet containing 100 grams per day of dark chocolate, in the form of commercially available "Ritter Sport" bars sold by Germany-based company Alfred Ritter. Blumberg's lab determined that each bar contained about 100 milligrams of flavanols, which are flavonoids that are relatively easy to measure. Blumberg estimates that there were about 400 milligrams of other flavonoids in each bar.
For 15 days, 10 volunteers with high blood pressure got those bars and 10 others ate white chocolate bars that contained no flavanols. After a 1-week break, the two groups switched the chocolate they were eating.
Each bar contained 480 calories, so the researchers advised the volunteers to eliminate some other sources of calories during the experiment. "We carefully instructed the patients to prepare the diet without increasing calorie intake," Ferri says. The subjects weren't obese initially, and none gained a significant amount of weight during the study.
During the half month when volunteers ate dark chocolate, their average systolic blood pressure decreased from 136 to 124 millimeters of mercury. Diastolic blood pressure fell from 88 to 80. There was no change in blood pressure in people while they ate white chocolate bars.
Furthermore, dark chocolate consumption accelerated the body's metabolism of blood sugar, or glucose, a process that involves the hormone insulin. Impaired insulin function can lead to diabetes. Dark chocolate also lowered cholesterol in the hypertensive patients, the researchers report in the August Hypertension.
In a parallel trial, Ferri and his Italian colleagues tested 15 people with blood pressure in the normal range. They, too, experienced a drop in blood pressure and an improvement in insulin function while eating a daily bar of dark chocolate. The Italians reported these findings in the March American Journal of Clinical Nutrition.
Neither the Italian researchers nor Blumberg received funding or products for the study from the chocolate industry. Harold H. Schmitz, chief scientist of Mars, says he knows of only one past trial that got no industry funding, and even it involved free chocolate provided by the industry.
Benefits associated with dark chocolate in past studies include improved flexibility of the arteries, which can contribute to lower blood pressure, and reduced stickiness of clot-forming blood components called platelets, which might reduce the risk of strokes and other problems associated with unwanted clotting (see Cardiovascular ShowdownChocolate vs. Coffee).
Once people have met their recommended daily intake of fruits, vegetables, and other nutritious foods, most of them can safely consume a small number of "discretionary calories" in any form they wish, says cardiovascular nutritionist Penny Kris-Etherton of Pennsylvania State University. But the calories in most chocolate bars exceed the typical discretionary range, which Kris-Etherton estimated to be no more than 200 calories for herself. "It's especially hard for someone with low calorie needs to work in a candy bar that might have 250 calories. I can't even eat a whole candy bar or I'll exceed my discretionary allowance for the day."
Given flavonoids' apparent benefits, she said, "I wish there were some other ways to incorporate cocoa in our diet apart from confectionary products and desserts."
That's one area where scientists are hard at work, according to Carl L. Keen, a professor of nutrition and internal medicine at the University of California, Davis, who has collaborated with chocolate manufacturer Mars. He said researchers are close to identifying specific, beneficial compounds in cocoa that could be used to enrich foods or create medications. Last month, Mars announced that it's courting pharmaceutical companies interested in synthesizing cocoa constituents such as flavonoids.
For now, consumers must carry on with little information about whether beneficial compounds that may be in their favorite chocolate offset all the sugar and fat in there too.
Chocolate is "a pleasure food with reduced health risks," says Lalita Kaul, a nutritionist at Howard University Medical School and a spokeswoman for the American Dietetic Association. "It has no health risks in moderation," she says.
But, she adds, "if somebody takes two bars a day, I'll say, 'Can we cut it down, maybe to one initially and then a half?'"
Jeffrey B. Blumberg
Jean Mayer USDA Human Nutrition Research Center on Aging
711 Washington Street
Boston, MA 02111-1524
American Dietetic Association
120 South Riverside Plaza, Suite 2000
Chicago, IL 60606-6995
University of L'Aquila
Department of Internal Medicine and Public Health
Piazzale S. Tomasi n.1
Department of Community Health and Family Practice
College of Medicine
520 W Street, NW
Washington, DC 20059
Carl L. Keen
Department of Nutrition
University of California, Davis
One Shields Avenue
Davis, CA 95616
Pennsylvania State University
Graduate Program in Nutrition
University Park, PA 16802
Harold H. Schmitz
c/o Marlene Machut
A Division of Mars, Incorporated
800 High Street
Hackettstown, NJ 07840
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