A new study out of George Washington University comes with some concerning news for chocolate lovers: a large portion of dark chocolate and other cocoa products in the United States are contaminated with heavy metals such as lead and cadmium. These findings, published in the journal Frontiers in Nutrition, raise possible health risks when consuming these treats one loves so well.
In eight years, researchers tested 72 consumer cocoa products for lead, cadmium, and arsenic. The results were unsettling: 43% of the products exceeded the maximum allowable dose level for lead, while 35% surpassed that for cadmium. At the same time, none of the products tested showed remarkable levels of arsenic.
“While it’s not practical to avoid heavy metals in your food entirely, you do need to be aware of what you’re eating and how much,” Leigh Frame, director of integrative medicine and associate professor of clinical research and leadership at the GW School of Medicine and Health Sciences. She emphasized the importance of the principle of moderation. Frame said the situation is comparable to other foods known to contain heavy metals, such as large fish like tuna and unwashed brown rice.
It also held a surprise that no one had expected: on average, organic dark chocolate products contained more of both lead and cadmium than their non-organic brethren. That finding challenges the common perception that organic products are somehow safer or healthier.
Those average levels of lead and cadmium found in this study are comparable to the highest contamination levels identified by the U.S. FDA in other foods,” says Jane Houlihan, national director of science and health for Healthy Babies Bright Futures. “We’d expect heightened risks for young children, pregnant women, and people who eat chocolate regularly, especially dark chocolate,” added Houlihan.
The chocolate industry—through the National Confectioners Association—answered back: “Chocolate and cocoa are safe to eat and can be enjoyed as treats as they have been for centuries.” During all phases of their production, they said, food safety and the quality of their products were important to them.
While a single serving of dark chocolate is unlikely to be a significant source of heavy metals for the average consumer, frequent consumption or consumption in combination with other sources of heavy metals could lead to exposures that exceed safe levels,” says lead author Jacob Hands, a medical student researcher at the GW School of Medicine and Health Sciences.
According to people like Tewodros Godebo, an assistant professor of environmental geochemistry at Tulane University, heavy metal exposure is more dangerous for some populations, including pregnant women and people with kidney disease. The worst affected, however, are children; this is because they can absorb a higher percentage of the lead they ingest, which can hinder brain development and lower intelligence quotient.
But so long as it’s consumed in small amounts, healthy adults shouldn’t be too concerned. “A typical serving of dark chocolate is 1 ounce, so eating 1 ounce every day or so is a pretty small risk in the grand scheme of things,” said Frame. She noted that consumers should be more concerned about other sources of lead exposure, including lead paint in older homes.
Part of what this underscores is that consumers should be educated about the potential hazards lurking in their favorite treats and about making informed choices in diet. While it may not be possible to avoid these heavy metals entirely, relative risks can still be understood to help individuals make better decisions for their health.
If dark chocolate contains plenty of health benefits—like improved cardiovascular health and cognitive performance—some elements of heavy metals like lead and cadmium are to be considered, and given these, some caution is needed. Moderation and awareness will support the enjoyment of these treats without compromising health.