By Sally Squires
Tuesday, February 12, 2008
According to a popular saying, there are four basic food groups: milk chocolate, dark chocolate, white chocolate and chocolate truffles.
Whether or not you subscribe to this sugarcoated view of nutrition, make no mistake: Chocolate not only can win hearts this Valentine's Day, but there's increasing evidence to suggest that it may help mend them, too.
Dark, sweet and with a "mouth feel" that some consider akin to the pleasures of sex, chocolate was once reserved for the royal and the very rich. Today, it is comfort food for the masses. The average American consumes about 11 pounds of chocolate per year, according to a study published in the American Journal of Clinical Nutrition. Women tend to eat more chocolate than men; Westerners seem to eat more than people in other regions of the country.
Popular, of course, doesn't necessarily mean nutritious. "Chocolate is not a health food," says Jeffrey Blumberg, director of the Antioxidants Research Laboratory at the Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University. "Broccoli, yes, you can eat all you want. Dark chocolate, I can't say that about."
Even so, Blumberg says his lab and others have found tantalizing evidence that ingredients in dark chocolate can help promote heart health, reduce the risk of some types of cancer, improve insulin sensitivity, control blood pressure and may even have a future role in preventing Alzheimer's disease.
"The whole thinking about chocolate has changed," says Penny Kris-Etherton, distinguished professor of nutrition at Pennsylvania State University. "At one point, we thought it had no adverse effects because it didn't raise blood cholesterol levels, but now we understand that it has beneficial effects."
The effects come from plant-based substances known as flavonoids, also found in green tea and in red wine. The darker the chocolate, the more flavonoids it generally contains, "although that's not a guarantee," Blumberg says. Chocolate with 70 percent or more cacao seems to pack the biggest flavonoid punch.
Studies show that these flavonoids lower blood pressure in people with hypertension and can keep it low in healthy individuals. On remote islands off the coast of Panama, the Kuna Indians eat a diet rich in fish and fruit. Unlike many indigenous peoples, their meals also contain enough sodium to rival that of people living in more developed parts of Panama. But the Kuna sidestep an age-related rise in blood pressure that occurs worldwide.
How? Scientists ascribe it to their practice of sipping five or more cups daily of a cocoa beverage.
Until about 100 years ago, sipping was pretty much the only way chocolate was consumed, according to Beth Kimmerle, author of "Chocolate: The Sweet History" (Collectors Press; 2005). That practice changed when Pennsylvania candymaker Milton Hershey and European chocolatiers figured out how to mass-produce chocolate bars. (Warm sipping chocolate is making a bit of a comeback in specialty groceries such as Trader Joe's and Whole Foods.)
Whether drunk or eaten, dark chocolate can help prevent platelets from clumping in blood, which helps set the stage for heart attacks and strokes. It improves vascular reactivity, the ability of blood vessels to dilate when stressed, in both "healthy people and people with heart disease," Blumberg says.
Recent studies also point to a possible role for chocolate flavonoids in prevention of breast and prostate cancer and in improving blood flow to the brain -- a finding that hints at protection against Alzheimer's disease.
Just don't look for those benefits from either white chocolate, Dutch cocoa or milk chocolate. All are either low in flavonoids or devoid of them.
Of course, even dark chocolate has some downsides. In January, Australian researchers reported in the American Journal of Clinical Nutrition that women ages 70 to 85 who consumed chocolate daily had lower bone density and strength than their counterparts who ate less.
Plus, with about 150 calories per ounce, "chocolate is high in calories and fairly high in fat," notes Dennis A. Savaiano, professor of foods and nutrition at Purdue University. Even so, "if you're going to have some candy," Savaiano says, "it seems to me that dark chocolate is among the best choices and, in moderation, it can be part of a heart-healthy strategy."