The presence of toxins in cacao-derived products, particularly in chocolates, raises concerns about food safety because children are more sensitive to toxicity and have a faster absorption rate than adults.
There are limited studies on harmful metals and critical components in chocolate.
In 2023, a Consumer Report finding suggested that dark chocolate brands could contain harmful levels of lead and cadmium. Now, scientists from Tulane University have found that dark chocolate poses no adverse risk for adults and contains nutritionally beneficial levels of essential minerals.
To test for 16 heavy metals, ranging from dangerous (lead and cadmium) to necessary (copper, iron, zinc), the study sampled 155 dark and milk chocolates from different international brands sold in the United States. The study then modeled the risk of ingesting one ounce of chocolates daily or more than two complete chocolate bars per week.
Only one brand of dark chocolate bars exceeded the international limit for cadmium in bars. According to the research, it contained more than 50% cacao (800 micrograms per kilogram). Only four dark chocolate bars had levels of cadmium that could be dangerous for children under three, or 33 pounds, on average.
Lead author Tewodros Godebo, assistant professor of environmental health sciences at Tulane University School of Public Health and Tropical Medicine, said, “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. We’ve found that it’s quite safe to consume dark chocolate and milk chocolates.”
Two chocolate bars passed California’s interim lead standards for dark chocolate, but neither was found to provide a health concern to adults or children.
Although lead and cadmium were the subject of two earlier U.S. studies on chocolate, this study used the largest sample size, extended the testing to 16 metals, and included a risk assessment of toxic metals that considered the essential minerals’ nutritional contribution.
The dark chocolates contained high concentrations of minerals like copper, iron, manganese, magnesium, and zinc; in fact, some of the chocolates analyzed supplied more than half of what adults and children needed each day.
Godebo said, “Not only is it packed with these essential minerals, but they can potentially reduce the absorption of toxic metals in the intestine since they compete for the same site.”
According to the study, a significant portion of the lead in chocolate originates from post-harvest processing. In contrast, cadmium penetrates the plant through the soil and ends up in the cacao bean.
After classifying the chocolates according to their geographical origins, scientists discovered that dark chocolates from South America had higher amounts of lead and cadmium than chocolates from Asia and West Africa, the latter of which is the country’s leading supplier of dark chocolate.
Godebo said, “But even for chocolates from South America, we found no adverse risk in eating an ounce per day.”
Journal Reference:
- Godebo, T. R., Stoner, H., Kodsup, P., Bases, B., Marzoni, S., Weil, J., Frey, M., Daley, P., Earnhart, A., Ellias, G., Friedman, T., Rajan, S., Murphy, N., & Miller, S. (2024). Occurrence of heavy metals coupled with elevated levels of essential elements in chocolates: Health risk assessment. Food Research International, 187, 114360. DOI: 10.1016/j.foodres.2024.114360