Other studies have suggested that "modern manufacturing of chocolate may induce losses of more than 80 percent of the original flavonoids from the cocoa beans," the researchers report, and the added sugar can contribute to weight gain, which can increase a person's risk of cardiovascular disease and diabetes.
The best advice is moderation — plus choosing chocolate with the lowest amount of sugar and the highest amount of cocoa. For those who want their little square of dark chocolate to pack the highest concentration of flavonoids, Ding recommends choosing brands that are "at least 70 percent cocoa."
Whether eating a little dark chocolate every day is a good long-term strategy for cardiovascular health, Ding says it's too soon to tell. "More research is needed," he says, to be sure the weight gain risk doesn't outweigh the benefits to your heart.
Candy Sagon writes about health and nutrition for the AARP Bulletin.