The Hazards of Heavy Metals in Chocolate

Consumer Reports on heavy metals in chocolate

Dark chocolate is often considered a healthy treat; a sweet alternative to sugar-rich candy and baked goods that’s chock full of minerals and fortified with the power to reduce inflammation and the risk of heart disease. But chocolate isn’t as wholesome as it seems, according to a recent study by Consumer Reports. While the tasty treat may help to reduce free radicals and lower blood pressure, there’s a price to pay for its decadence. Tests of nearly 50 chocolate products revealed that one third contained concerning levels of lead and cadmium, heavy metals that, when consumed in high doses, can severely damage essential organs like the brain, lungs, kidney and liver. But how dangerous is eating chocolate, really?

Interestingly it was not the chocolate’s quality that determined its heavy metal content in the study. Big name brands like Hershey’s and Nestlé were as likely to contain disturbing levels of cadmium and lead as generic brands from national retailers like Costco and Walmart, and specialty brands like Droste and Navitas. The latter, in fact, contained far more lead than the counterparts they examined from larger brands.

Nor was the presence of cadmium and lead restricted just to dark chocolate in bar form. It was found in high levels in all types of chocolate, including cocoa powder, chocolate chips, brownie and cake mix, and even hot cocoa.

How Do Heavy Metals End Up in Chocolate?

Journey of Cadmium from soil to chocolate bar courtesy of Science Direct

There’s more than one way in which these metals find their way into cacao. Lead is a post-harvest byproduct. Cacao beans left to dry in the sun become magnets for dust and dirt that can contain particles of lead and other harmful elements. The metal adheres to the beans’ surface, mixing into the chocolate as it’s processed. Some products including Walmart’s Great Value Milk Chocolate Flavor Hot Cocoa Mix, Droste Cacao Powder and Target’s Good & Gather Semi-Sweet Mini Chocolate Chips had lead levels that could be more than three times the standard recommended dose per day.

Cadmium, on the other hand, is typically absorbed from the soil in which cacao trees are grown. By the time the chocolate is harvested, it is already impregnated with the heavy metal. The higher the percentage of cacao in the chocolate, the higher it is likely to be in cadmium.

Cadmium is especially common in cacao grown in Ecuador, Colombia and Brazil where the landscape’s geography lends itself to high natural concentrations of the substance, Mayesse DaSilva, a soil scientist with the Alliance of Bioversity International and the International Center for Tropical Agriculture (CIAT), told the Fine Chocolate Industry Association. “Cacao is very efficient in the uptaking,” she said.

How Dangerous Are Heavy Metals in Chocolate?

Joshua D. Lambert. Photo courtesy of Joshua D. Lambert.

But while the metal levels detected by the Consumer Reports study is alarming on paper, food scientists aren’t sure whether the numbers fully translate to human health. Many foods, including spinach, carrots, sweet potatoes and tap water, contain cadmium and/or lead. The question, says Joshua D. Lambert, professor of food science at Penn State University, is whether those metals are 100% bioavailable. In other words, does all of the cadmium in chocolate actually end up in the human body when it’s eaten?

“It’s not clear that the cadmium and lead in chocolate are released during digestion, nor is there evidence showing that consumption of these products leads to adverse health effects,” he says. “It’s easier to show that a heavy metal like cadmium or lead is in a product than it is to show that exposure to that product is harmful to your health. If the cadmium isn’t released from the product during digestion, it’s not going to be absorbed.”

For its part, the U.S. Food and Drug Administration says the discovery of heavy metals across the chocolate industry is nothing to worry about. “While the presence of cadmium and lead in chocolate has been the subject of considerable media attention, experts around the world have found that chocolate is a minor source of exposure to these contaminants internationally,” they said in a statement after the study’s release. Also, the FDA limits are more than 17 times what CR used for lead in their study.

Consumer Reports does prove one thing, though: Some brands are better at preventing high levels of heavy metals from contaminating its chocolate than others. And while scientists are working to find new ways to minimize their appearance in cacao—increasing the soil’s PH level is showing promising results for reducing cadmium, for example, said DaSilva—it’s unlikely that chocolate will ever be completely free of those harmful hangers on.

The Bottom Line

Chocolate and cocoa powder

This doesn’t mean that chocolate, even dark chocolate with its higher cadmium concentrations, isn’t still safe to eat in moderation for most adults and older kids (heavy metals pose a higher risk to pregnant women and young children but they would have to eat an extremely large amount for it to be of concern). But like with all chocolate, reaping its health benefits while avoiding its pitfalls is a balancing act. Trading dark chocolate for milk chocolate may reduce cadmium exposure in some cases, but it also reduces the health benefits associated with dark chocolate itself.

Despite the data collected by Consumer Reports from 48 different chocolate products, there’s very little risk to satisfying the craving for dark chocolate, chocolate cake, or hot chocolate in reasonable amounts.