Is it true that a chocolate a day will keep the doctor away? That's what some candy lovers are reading in Valentine's Day promotional material.
Although cocoa has a history of medicinal use dating back 3,000 years, most chocolate bars you can buy at the checkout stand probably won't impart health benefits.
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Through the ages cacao, or cocoa beans, grown mainly in Latin America, Africa and Asia, have been used to help treat fatigue, angina, constipation, dental problems (tartar), dysentery, gout, an "overheated" heart, skin eruptions, fevers and seizures. The beans, which are the source of the chocolate we know today, contain "flavanols," naturally occurring plant compounds also found in tea, red wine and apples. Their properties have been studied as heart disease inhibitors.
"I think you could make the case that some cocoa can contribute to a healthy diet. The data look pretty good right now," says Carl L. Keen, professor and chair of the department of nutrition at University of California, Davis. "The flavanols in cocoa help maintain a healthy vascular system. They reduce blood clotting -- an aspirin-like effect -- reduce oxidative damage and improve blood flow." A study in last month's American Journal of Clinical Nutrition found cocoa also reduces inflammation.
In 1997, Harvard professor Norman K. Hollenberg published a landmark epidemiological study focused on cocoa. He found that high blood pressure was a rarity among Panama's Kuna Indians, who also didn't experience the typical age-related increases. He at first attributed it to genetic protection. But when the Kunas migrated to Panama City, their blood pressure increased, pointing to an environmental cause. Upon examination, Hollenberg found the Kunas consumed large amounts of a drink made from unprocessed cocoa that they stopped drinking when they moved to the city.
Subsequent experiments conducted by Hollenberg and others have found that cocoa, if high in flavanols, relaxes the blood vessels -- an important protection against hypertension and heart disease.
Ironically, though, flavanols have such a bitter taste that they are usually removed from foods that are processed. Most research about chocolate's health benefits have used unsweetened cocoa or specially formulated high-flavanol chocolate.
"Most of the flavanols are in the cocoa beans and the level decreases with each processing step when it goes from the bean, to the cocoa powder and ultimately a finished chocolate product," says Leah Porter, vice president for scientific affairs of the Chocolate Manufacturers of America, which represents most Northern American chocolate manufacturers and funds related research.
Since flavanols and their health benefits are a recent discovery, chocolate companies are just beginning to see if there are ways to keep flavanols consistently high, but still have a tasty, popular product.
In the past five years, companies such as Mars Inc. -- famous for M&Ms -- and Nestle have been largely responsible for the advancement of cocoa research. Mars has collaborated with institutions such as the Harvard Medical School, the University of California, and even the U.S. Department of Agriculture's Agricultural Research Service. Through their research and others', discoveries about cocoa's positive effect on blood vessel function, for example, have been made.
If you're eating chocolate for its health benefits, you'll need to be discriminating in your selections.
In general, you'll get more flavanols with less processing. At the top of the short list is unsweetened cocoa powder -- not the alkalized "Dutch processed" kind, in which the flavanols have been degraded or reduced.
Look for chocolate that has the highest possible percentage of cocoa. To save calories, look for chocolate with lower fat and sugar levels. A semisweet or bittersweet chocolate with a high cocoa percentage would be your next choice. Some chocolates contain as much as 70 percent cocoa, but they can have as little as 35 percent and still be considered dark chocolate. The percent of cocoa in milk chocolate can be much lower, so I don't recommend it for health benefits. I recommend cocoa or an ounce per day of dark chocolate, which may be about 110 to 150 calories, depending on the chocolate. Any more than that and you're probably going to take in too many calories for weight control.
One company that publicizes the flavanol content of its chocolate is Mars, only in its Dove Dark. In fact, Mars has provided most of the chocolate and cocoa used in the studies. The other analyses below come from averages of various chocolate products collected by the USDA labs, which have collaborated with Mars on flavanol analysis technology.
Katherine Tallmadge is a Washington-based nutrition consultant, author of "Diet Simple" (Lifeline Press, 2004) and spokesman for the American Dietetic Association. Send e-mails to her at Katherine@personalized nutrition.com">Katherine@personalized nutrition.com.