Chocolate Hearts - research indicates chocolate contains antioxidants called flavonoids that reduce risk of cardiovascular disease

Science News, March 18, 2000 by Janet Raloff

Test-tube studies by Schmitz's team at Mars dovetail with the findings by both groups. Chocolate procyanidins can dampen the activity of enzymes that trigger inflammation and ratchet up production of nitric oxide, Schmitz reported at the meeting. Moreover, he notes, both of these actions may be independent of the flavonoids' antioxidant role.

Yet Cesar G. Fraga of the University of Buenos Aires hails the procyanidins' antioxidant activity. In work funded by Mars, he has demonstrated a rise of chocolate-derived procyanidins in the blood of men and women who had just eaten semisweet-chocolate candies. His team found that blood sampled 2 hours after candy consumption protected its circulating lipids from oxidation. The more chocolate eaten, the better the protection.

Earlier test-tube studies, he says, indicate that the procyanidins may function as a first line of defense against damaging oxidants--sparing vitamin C and other antioxidant vitamins that would otherwise be destroyed in the battle. In these experiments, while all of the tested procyanidins appeared active, the pentamer offered the best protection.

Nutritionist Carl L. Keen, Fraga's collaborator at UC Davis, has conducted additional Mars-funded work. At the AAAS meeting, he unveiled data from new studies indicating that flavonoid-rich foods may benefit the heart yet another way, by damping the reactivity of blood platelets.

When stimulated by any of several chemical triggers, these cells turn sticky, helping blood to clot. Doctors often recommend that people at risk of heart attacks take aspirins to reduce clotting. Keen's data now show that chocolate's procyanidins work like especially mild aspirins.

His group gave water, procyanidin-rich cocoa, or alcohol-free red wine to groups of 10 men and women. The researchers sampled and tested the volunteers' blood 2 and 6 hours later.

Though both the wine and cocoa significantly delayed the blood's clotting time, only the cocoa protected blood platelets from fragmentation. Platelets tend to fragment when they become overly stickey, Keen says.

At the Experimental Biology meeting in San Diego next month, Penny Kris-Etherton and her colleagues at Pennsylvania State University in State College, who are funded by ACRI, plan to report yet another cardiovascular benefit. In the 24 volunteers whom they studied, diets enriched with dark chocolate or cocoa powder raised the individuals' high-density lipoprotein (HDL) cholesterol, the so-called good cholesterol.

"This is important," Kris-Etherton says, "because a higher ratio of HDLs to LDLs is associated with a decreased risk of heart disease."

Why should consumers trust the tantalizing data on chocolate if they're all coming from industry-funded research? "That's a valid question," acknowledges nutritionist John W. Erdman of the University of Illinois at Urbana-Champaign who cochaired the AAAS symposium on chocolate. Though he believes people should be skeptical, he also points out that these studies would never get off the ground without candy-industry financing.