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  • Writer's pictureSophia Kamveris, MS, RDN

Heavy Metals in Dark Chocolate

You may have read that dark chocolate is a source of anti-oxidants—those are the healthy, plant based compounds that protect against inflammation in your body. But have you also heard that some dark chocolate is a also a source of heavy metals—specifically lead and cadmium?

A Consumer Reports study tested 28 chocolate bars and used California’s maximum allowable dose for cadmium (4.1 mcg) and lead (0.5 mcg) as the standard. All brands tested had detectable amounts of both metals in their product. According to the report, safer choices included Ghirardelli, Mast, Valrhona, and Taza Chocolate as their bars had cadmium and lead levels under California’s maximum allowable dose level. Hershey and Trader Joe’s dark chocolate had the highest levels of heavy metals in their study.

We have all heard of natural arsenic in the soil that ends up in rice or in well water. This is a little similar. Chocolate is made from the seeds of the cacao tree. These seeds can also become contaminated by pollutants in the soil. Cadmium in cacao beans is introduced from the soil via tree roots. Lead is introduced from environmental toxins and contamination occurs post-harvest, during the drying and processing phases of the beans. I did read an article (not related to the Consumer Reports study) that cited cadmium is more prevalent in the soil of South and Latin America due to volcanic nature of the soil as opposed to West Africa soil. So, maybe pay attention to country of origin that should be listed on the labels.

Recommendations included not giving dark chocolate to children or pregnant women. For the rest of us, limit consumption to a one-ounce serving a few times a week. Dark chocolate also contains more cocoa than milk chocolate, so it has higher levels of heavy metals—maybe alternate between the two.

In Good Health,


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