US study finds some cocoa products contain traces of metals

Dark chocolate lovers may want to limit their consumption to around 28 grams a day to stay on the safe side, according to researchers. 

Research from George Washington University (GW) found a percentage of cocoa products in the US contain heavy metals that exceed guidelines. The study, ‘A Multi-Year Heavy Metal Analysis of 72 Dark Chocolate and Cocoa Products in the USA’, was published in Frontiers in Nutrition.

Foods with high lead levels 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 (eg, 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, particularly with cocoa products labelled organic, as they may have higher heavy metal concentrations.

A serving size of dark chocolate is typically around 28 grams and has been generally suggested to have health benefits including cardiovascular health, cognitive performance and chronic inflammation. However, the research is limited and concerns about heavy metals have yet to be taken into account.

GW researchers analysed 72 consumer cocoa products, including dark chocolate, every other year over an eight-year period for contamination with lead, cadmium and arsenic — heavy metals that pose a significant health hazard in sufficient amounts.

The study found that 43% of the products studied exceeded the maximum allowable dose level for lead, 35% of the products studied exceeded the maximum allowable dose level for cadmium and none of the products exceeded the maximum allowable dose level for arsenic.

The researchers used a threshold of maximum allowable dose levels to assess the extent of heavy metal contamination in an array of chocolate products, found on grocery store shelves.

“We all love chocolate but it’s important to indulge with moderation as with other foods that contain heavy metals including large fish like tuna and unwashed brown rice,” Frame said.

“While it’s not practical to avoid heavy metals in your food entirely, you must be cautious of what you are eating and how much.”

Access the full research findings here.

Image credit: iStock.com/Eva-Katalin