The health benefits of chocolate lie in the flavanols and other beneficial compounds, most of which are found in dark chocolate. “Very generally speaking, the darker the chocolate—meaning the higher the cocoa percentage—the more flavanols. But the growing region and the way cocoa beans are processed makes a big difference,” says Lee Berk, DrPH, associate dean of research at the School of Allied Health Professions, Loma Linda University School of Allied Health Professions in California, who has studied the effects of chocolate on the brain.
Cocoa percentage, however, was not a reliable indicator of flavanol content in tests by ConsumerLab.com, an independent testing lab that reports on dietary supplements and other health products. In an analysis of 16 dark chocolate bars (all were 70 percent to 100 percent cocoa except for one 45 percent bar), tests revealed a fourfold difference in flavanols per gram, which translates into a gigantic difference in flavanols per calories. The report found that to get 200 mg of flavanols—an amount some experts recommend—could cost anywhere from 71 calories for a 100 percent bar to 746 calories for one of the 70 percent bars analyzed.
Another unfortunate finding: Some bars contain cadmium, a metal that can be toxic. (ConsumerLab.com also tested cocoa powders; nearly all had excessive levels.) The main culprit appears to be the cocoa trees themselves. Certain varieties pull more cadmium from the soil than others, according to a study of cocoa trees in various regions of Peru, published in Science of the Total Environment in 2017. ConsumerLab.com found that just a few ounces of some bars contained cadmium exceeding California’s “oral dose” limit of 4.1 micrograms per day. (There are no U.S. federal guidelines for cadmium in foods, although the European Union has them.)
“I’m concerned about the high cadmium levels in cocoa powders and some dark chocolates,” says Tod Cooperman, MD, ConsumerLab.com’s president. “They should be consumed in moderation. Certainly not more than one serving [one ounce of dark chocolate and one tablespoon of cocoa powder] of either per day.” ConsumerLab.com did uncover a few bars low in cadmium and rich in flavanols, such as its top pick: Endangered Species Dark Chocolate with 88 percent cacao.
For ways to eat chocolate other than from a candy bar, check out these five chocolate-based recipes. For information on the health benefits of chocolate, read "Is Chocolate Good for the Brain?"
