Heavy metals and chocolate are an unlikely combination by all means, but that is exactly what a study has found.

The study from George Washington University revealed concerning levels of heavy metals in a significant percentage of cocoa products in the US, with organic products showing higher contamination levels.

Led by Leigh Frame and medical student Jacob Hands at the GW School of Medicine and Health Sciences, it analysed 72 consumer cocoa products, including dark chocolate, over an eight-year period for lead, cadmium, and arsenic contamination.

The findings were published on Wednesday, in the journal Frontiers in Nutrition.

They indicated that 43 per cent of the products studied exceeded the maximum allowable dose level for lead and 35 per cent for cadmium. No products surpassed the arsenic limit. Notably, organic products exhibited higher levels of lead and cadmium than non-organic counterparts.

Leigh Frame, the director of integrative medicine at GW, emphasised moderation in consuming chocolate and other foods that may contain heavy metals, such as large fish like tuna and unwashed brown rice. “While it’s impractical to avoid heavy metals in food entirely, it’s crucial to be mindful of what and how much you’re consuming,” Frame advised.

The study used a threshold of maximum allowable dose levels to evaluate the extent of contamination. For most consumers, a single serving of these cocoa products may not pose significant health risks, but multiple servings or combined consumption with other heavy metal sources could lead to exposure exceeding safe levels.

Foods with high lead levels include shellfish, organ meats, and foods or supplements grown in contaminated soil or imported from countries with less stringent regulations.

For cadmium, concerns extend to certain seaweeds, particularly Hijiki. Consumers should be aware of potential cumulative exposure risks, especially with organic cocoa products.

Despite dark chocolate’s reputed health benefits, including cardiovascular and cognitive advantages, the study highlights the need for further research, especially considering heavy metal contamination.