The research involved testing 155 dark and milk chocolates from various global brands available in the United States for the presence of 16 heavy metals, including toxic ones like lead and cadmium, as well as essential ones like copper, iron, and zinc. The study then calculated the risk associated with consuming one ounce of chocolate per day, which is equivalent to eating more than two whole chocolate bars in a week.
In 2023, Consumer Reports found that certain dark chocolate brands could contain unsafe levels of lead and cadmium, causing concern among chocolate lovers.
However, a recent study conducted by Tulane University and published inFood Research International has discovered that dark chocolate is not harmful to adults and contains essential minerals that are beneficial for the body. The study examined 155 dark and milk chocolates from different global brands sold in the United States, testing for 16 heavy metals, including both toxic (lead and cadmium) and essential (copper, iron, zinc) elements. The researchers then calculated the risk of consuming one ounce of these chocolates daily, which is equivalent to eating more than two whole chocolate bars a week. The results showed that only one brand of dark chocolate exceeded the international standards for heavy metal content.The limit for cadmium in bars with more than 50% cacao is 800 micrograms per kilogram. Only four dark chocolate bars had cadmium levels that could pose a risk to children weighing 33 pounds or less, which is the average weight of a 3-year-old in the U.S.
Lead author Tewodros Godebo, assistant professor of environmental health sciences at Tulane University School of Public Health, stated that “For adults there is no adverse health risk from eating dark chocolate, and although there is a slight risk for children in four of the 155 chocolate bars sampled, it is not common to see a 3-year-old regularly consume more than two bars of chocolate per week.”The study in the Journal of Agricultural and Food Chemistry and Tropical Medicine found that consuming dark chocolate and milk chocolates is safe. Two chocolate bars were tested for lead and found to have levels above California’s interim standards for dark chocolates. However, it was determined that neither posed adverse risks to children or adults. This study was the largest of its kind, testing for 16 metals and including a risk assessment that accounted for the nutritional contribution of essential minerals. Two previous studies in the U.S. had also examined the presence of lead and cadmium in chocolate, but this study expanded the scope of testing.
According to Godebo, dark chocolates have high levels of important nutrients like copper, iron, manganese, magnesium, and zinc. Some of the chocolates tested provided over 50% of the daily requirement for both children and adults.
Godebo also stated, “In addition to being rich in these necessary minerals, dark chocolates have the potential to reduce the absorption of toxic metals in the intestine as these metals compete for the same site.”
The study revealed that the lead content in chocolate largely comes from post-harvest processing, while cadmium is derived from the soil and passes through the plant into the cacao bean.
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The researchers also categorized the chocolates by region and discovered that dark chocolates from South America contained higher levels of cadmium and lead compared to chocolates from Asia and West Africa. The latter is a primary source of dark chocolate for the United States.
“However, even with chocolates from South America, we determined that there is no significant risk in consuming an ounce per day,” Godebo explained.
