Research shows that 43% of cocoa products exceed safety levels for lead

A new study from George Washington University shows that a disturbing percentage of cocoa products in the US contain heavy metals that exceed guidelines, including higher concentrations in organic products.

The study, “A multi-year heavy metal analysis of 72 dark chocolate and cocoa products in the US” was published on July 31, 2024 in Limits in nutrition.

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 in sufficient quantities pose a significant health hazard.

“We all love chocolate, but it’s important to enjoy it in moderation, as with other foods containing heavy metals, including large fish like tuna and unwashed brown rice,” says Leigh Frame, director of integrative medicine and associate professor of clinical research and leadership at the GW School of Medicine and Health Sciences.

“While it’s not practical to completely avoid heavy metals in your food, you should be careful about what you eat and how much.”

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

The researchers used a threshold of maximum allowable dose levels to assess the extent of heavy metal contamination in a range of chocolate products found on supermarket shelves.

Key findings:

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

For the average consumer, consuming one 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 may result in exposures that exceed the maximum allowable dose level.

Foods high in lead may include animal foods that can bioaccumulate 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). For cadmium, the main concerns are the same, with the addition of some seaweeds, especially Hijiki seaweed.

Consumers should be aware of potential cumulative exposure risks, especially with cocoa products labeled organic, as they may contain higher concentrations of heavy metals. A serving of dark chocolate is typically one ounce and it is widely suggested to have health benefits including cardiovascular health, cognitive performanceAnd chronic infection. However, research is limited and concerns about heavy metals have yet to be taken into account.