High levels of toxic metals found in popular chocolate brands

A George Washington University study found significant heavy metal contamination in American cocoa products, especially organic ones, highlighting the need for cautious consumption due to potential health risks.

The authors suggest that those who enjoy dark chocolate should consider limiting their consumption to one ounce per day to remain cautious.

A recent study from George Washington University reveals that a worrying percentage of cocoa products in the U.S. exceed heavy metal guidelines, with organic products showing even higher concentrations.

GW researchers analyzed 72 consumer cocoa products, including dark chocolate, every two years over an eight-year period for contamination with lead, cadmium and arsenic — heavy metals that pose a significant health risk in sufficient quantities.

“We all love chocolate, but it’s important to consume it in moderation, as with other foods that contain heavy metals, such as large fish like tuna and unwashed brown rice,” said Leigh Frame, director of integrative medicine and adjunct professor of clinical research and leadership at GW’s School of Medicine and Health Sciences. “While it’s not practical to completely avoid heavy metals in foods, you do need to be careful about what you eat and how much.”

The unique study was led by Leigh Frame and senior study author Jacob Hands, a medical student researcher in the Frame-Corr Laboratory at GW’s School of Medicine and Health Sciences.

Researchers used a threshold of maximum allowable dose levels to assess the degree of heavy metal contamination in a variety of chocolate products found on supermarket shelves.

Key results:

• 43% of the products studied exceeded the maximum permitted dose level of lead.
• 35% of the products studied exceeded the maximum permitted dose level of cadmium.
• None of the products exceeded the maximum allowable dose level of arsenic.
• Surprisingly, products labeled as organic showed higher levels of lead and cadmium compared to non-organic products.

Key findings:

For the average consumer, consuming a single serving of these cocoa products may not pose significant health risks based on the average concentrations found. However, consuming multiple servings or combining consumption with other sources of heavy metals could lead to exposures exceeding the maximum permitted dose level.

Foods with high levels of lead may include animal foods that can bioaccumulate with heavy metals (shellfish, organ meats) and foods or herbal supplements grown in contaminated soil and/or imported from countries with less regulation (e.g., China, Nigeria, India, Egypt). In the case of cadmium, the main concerns are the same with the addition of some seaweeds, especially Hijiki seaweed. Consumers should be aware of the potential risks of cumulative exposure, particularly with cocoa products labeled as organic, as they may have higher concentrations of heavy metals. A serving of dark chocolate is typically one ounce and has generally been suggested to have health benefits, including cardiovascular health, cognitive performance, and chronic inflammation. However, research is limited and concerns about heavy metals have not yet been addressed.

Reference: “A Multi-Year Heavy Metal Analysis of 72 Dark Chocolate and Cocoa Products in the U.S.,” by Jacob M. Hands, Mark L. Anderson, Tod Cooperman, Jared E. Balsky, and Leigh A. Frame, June 25, 2024. Frontiers in nutrition.
DOI: 10.3389/fnut.2024.1366231