This research focused on looking at metal contamination of consumer products containing cocoa. Research is ongoing about what levels of certain metals are safe for people to consume.

While these results appear concerning, researchers found that over 97% of products were below the FDA interim reference level for lead.

In addition, looking at the median concentration of the metals, researchers found the amounts were lower than Prop 65 MADL levels.

Thus, they believe that product outliers could have had a major impact on their findings and suggest that single servings of most products are safe for most consumers.

At the same time, they note that consuming multiple servings daily or combining a serving with other food sources of heavy metals could lead to exposure of more than the Prop 65 MADLs.

They also found that later cohorts of products, the ones from 2016, 2019, and 2022, had lower concentrations of metals than the products from 2014.

Speaking to Medical News Today, study author Jacob Hands, a medical student at the George Washington University School of Medicine and Health Sciences highlighted the following:

“The heavy metal content of consumer dark chocolate and cocoa products are on average unlikely to demonstrate any significant adversity to the consumer. However, levels of cadmium and, rarely, lead are unacceptably high in a significant minority of these products which should prompt concern for more stringent evaluation of the cocoa source and quality used by distributors.”

He further explained that: “Cadmium, like lead, is inherently toxic, and its accumulation can affect nearly every single major organ in the body. Therefore, the consumption of certain cocoa products over time and among certain groups — [such as] pregnant women and children — could be problematic.”

This research does have limitations to consider. First, researchers only looked at a relatively small number of products and focused on products available for purchase in the domestic U.S. Thus, future research could focus on additional products purchased in other regions.

There is also a lack of data in certain areas, making it difficult to determine what metal contamination levels are dangerous to people. For example, the study notes that “there has never been a safe serum level of Pb [lead] consumption identified with any value.” The U.S. government also does not have a federal limit for cadmium.

The authors noted that further research could look at metal exposure from the whole diet, to better help determine potential interventions or health policies.

They sugggest that consumers can be exposed to metal contamination from multiple sources, and outlier cocoa products containing higher amounts of metals could be problematic. Another component would be addressing harvesting and manufacturing practices that contribute to metal contamination in food.

Hands noted that: “Further research would be to periodically screen these same products and develop guidelines, perhaps publicly or privately (like CA prop 65), to more carefully regulate certain harmful contaminants, like heavy metals, in our dark chocolate.”

Finally, it is also important to point out that three of the study’s authors were employed by ConsumerLabs.com, which could create a potential conflict of interest.

Does this all mean everyone should throw out their chocolate? Not necessarily. However, the study authors believe it could indicate the need for more regulation in this area.

The data also highlight that organic products and other food products that consumers believe to be of higher quality still carry the risk of metal contamination.

Registered dietitian nutritionist Karen Z. Berg, MS, RD, CSO, CDN, who was not involved in the current research, told MNT that:

“The findings of this study are most interesting when it talks about the ‘higher-quality’ products not having any effect on the amount of metals found. In some cases, organic actually had higher metals. The general public steadfastly believes that non-GMO, organic, or fair-trade on the label always means healthier, and this is a great example how that is not at all the case.”

Berg further noted that the results primarily point to caution for certain groups like young children and how the results point to the need for dietary variation.

She explained that: “Eating or drinking items that have a high level of heavy metals can lead to heavy metal poisoning which can be quite serious […] Small amounts of heavy metals, like what is found in cocoa, rice and rice-based products, tea and some sources of water are usually not dangerous for the general population.”

“Heavy metal is found in many foods that come from the ground since it is often from the soil,” said Berg. “So this is a good reason to eat a varied diet so that you don’t get too much of one food that could potentially have more heavy metals than others.”

“Babies, children and expectant mothers should be more careful about where their food and water comes from to avoid unnecessary exposure to heavy metals, since they impose more of a risk for them,” she further advised.

It is also essential to balance the potential metal contamination concerns with the possible health benefits of dark chocolate, such as improved cardiovascular health or increased insulin sensitivity.

Hands ended on a positive note:

“Overall, I’d like to emphasize that there is no credible evidence, at this time, that the levels contained in these products are acutely affecting any particular population. Moreover, we do not in any way advocate for the reduction of dark chocolate consumption owing to its demonstrated association with numerous health benefits. This is all to say we should be more circumspect consumers and, perhaps, demand greater transparency and quality from large manufacturers.”