Spanish researchers put 42 men and women on a diet that included 40 grams of unsweetened cocoa powder (about 1.4 ounces) mixed with skim milk daily, or plain skim milk. After one month, those who drank the cocoa-flavored milk had lower levels of inflammatory markers associated with heart disease than those drinking the milk alone.
That result was critical because the participants, whose average age was about 70, were at high risk of cardiovascular disease because they had diabetes and three or more risk factors for heart disease, including smoking, high blood pressure, high levels of LDL "bad" cholesterol (more than 160 milligrams per deciliter), low levels of HDL "good" cholesterol (below 35 milligrams per deciliter), obesity or a family history of early coronary heart disease.
The inflammatory markers, called adhesion molecules, are proteins that cause white blood cells to stick to the walls of the arteries, which can lead to the formation of atherosclerotic plaques, explained Shelley McGuire, an associate professor of food science and nutrition at Washington State University and a spokeswoman for the American Society for Nutrition.
"One of the major strengths of the study was they were measuring adhesion molecules, which we have recently learned are very important in the formation of atherosclerosis," McGuire said. "Another strength is that the study was randomized and controlled. Because of this, we can pretty confidently say there was something in the cocoa powder that had an effect."
The researchers also found that the cocoa powder group had an increase in HDL cholesterol, which can help reduce levels of LDL cholesterol and has been shown to have anti-inflammatory, antioxidant properties.
The study is published in the November issue of the American Journal of Clinical Nutrition.
During the study, participants didn't take additional vitamins or supplements, and the only cocoa-containing products they consumed were those provided by researchers.
Previous research has suggested chocolate may be beneficial for heart health because it contains anti-inflammatory chemicals called polyphenols. Polyphenols are also found in wine, coffee and tea, along with fruits and vegetables such as apples, broccoli, onions, blueberries, blackberries, cherries, strawberries, plums and red grapes, said Connie Diekman, director of university nutrition at Washington University in St. Louis.
"One of the best ways to get plenty of polyphenols is to consume lots of fruits and vegetables," Diekman said.
The researchers noted the anti-inflammatory effects derived from cocoa were modest compared to those observed for other foods rich in polyphenols, such as wine.
And before you start inhaling candy bars, which are high in fat and calories, researchers noted that study participants were given non-fat, sugar-free cocoa powder and skim milk. Even then, they gained a small amount of weight.
In the study, the chocolate milk contained about 136 calories. If adding cocoa to your diet, be sure to reduce calories somewhere else, or get some extra exercise.
"My recommendation, as a registered dietitian, would be for people to look at cocoa -- whether in the form of cocoa or chocolate -- as a part of a healthful eating plan, not a magic bullet for reducing inflammation," Diekman said. "If including cocoa and small amounts of chocolate in an otherwise healthful eating plan helps people enjoy what they eat and stick with that plan, then these things can fit."
In findings that should come as no surprise, researchers noted that "adherence to the dietary protocol was excellent."
More information
The National Confectioners Associationhas more on cocoa.
SOURCES: Connie Diekman, M.Ed., R.D., director, university nutrition, Washington University, St. Louis; Shelley McGuire, Ph.D., associate professor, food science & human nutrition, Washington State University, Pullman, Wash., and spokeswoman, American Society for Nutrition; November 2009, American Journal of Clinical Nutrition
Last Updated: Oct. 23, 2009