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There’s some sour news surrounding a favorite sweet treat: A study found that many popular chocolate products sold in the U.S. contain heavy metals — and some could have levels that exceed guidelines.
Researchers led by a team at George Washington University analyzed 72 common cocoa products, including dark chocolate, on four separate occasions between 2014 and 2022 for contamination with lead, cadmium and arsenic — three heavy metals that in high amounts have been linked to health conditions including cardiovascular disease, kidney disease and cancer.
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The study found that 43 percent of the products exceeded the maximum dose deemed safe by California’s Proposition 65 for lead; 35 percent exceeded the maximum allowable dose level for cadmium. None of the products exceeded the threshold for arsenic.
Importantly, the researchers note, the median concentrations of each metal tested were lower than the maximum allowable dose levels (0.5 micrograms per day for lead and 4.1 micrograms per day for cadmium, according to California’s guidelines, which are among the most stringent regulations). The majority of chocolate products tested fell below lead limits established for young children by the U.S. Food and Drug Administration, which are less strict than California’s guidelines.
The study, published in the journal Frontiers in Nutrition, follows research that reached similar results. “Chocolate products that contain cocoa have, to some extent, heavy metals in them,” study author Leigh Frame told AARP.
Heavy metals are naturally occurring elements that can get into the food supply through soil and water and sometimes processing. “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,” Frame said in a statement.
Moderation is key
The research may be unsettling for chocolate lovers, but Ana M. Rule, an assistant professor in the Department of Environmental Health and Engineering at Johns Hopkins Bloomberg School of Public Health, says, “I don’t think anybody needs to freak out” if we look at the big picture.
While metal contamination in the food supply remains a global issue, concentrations in the U.S. have declined in recent decades, the study’s authors note. Environmental health researchers point out that folks with a moderate intake should be fine. “If you’re a serious chocolate eater, maybe you need to [lower] your consumption,” Rule says.
When it comes to chocolate, it can be hard to set limits, says Frame, the director of integrative medicine at the George Washington School of Medicine and Health Sciences. “It's very difficult to sit down and have a small amount of chocolate, right?”
Based on the accumulating research, she and other researchers recommend sticking with a 1-ounce daily serving if you do indulge, or 2 ounces every other day.
“[The findings] should not mean, ‘Oh, I can never have chocolate,’ ” Frame says.
One reason: Much of the research that linked dark chocolate with potential heart health benefits studied chocolate at this serving size, Frame says, so you won’t miss out on any possible perks.
“And we’re thinking at that level of intake, you’re probably not seeing detriments from the heavy metals,” Frame adds. Another study published this summer in the journal Food Research International found that consuming an ounce of dark chocolate daily doesn’t pose a health concern for adults.
“You don't want to have a ton of chocolate anyways as part of a healthy life,” says Laura Corlin, an environmental epidemiologist at Tufts University School of Medicine. Even bars rich in cocoa content can contain high amounts of fat, sugar and calories, which can lead to excess weight gain and the health complications that ensue.
In response to this latest study, the National Confectioners Association, an industry trade organization, issued a statement that “consumers understand that chocolate and candy are occasional treats and not center-of-the-plate foods.”
Diversify your diet
Keep in mind that foods other than chocolate can contain heavy metals, including rice, root vegetables and fish, so consuming them in combination or in high amounts could push you over the recommended safety limit. Making sure your diet is diverse can help prevent this, researchers say.
“I think if people are having varied diets, I wouldn’t worry too much about it, unless you’re having [a lot] of certain foods that are known to be high in these heavy metals,” Corlin says.
Foods have labels indicating high amounts of fat, salt, sugar and the like, but there is no label for products high in heavy metals, Frame says.
Even “organic” doesn’t guarantee your chocolate bar will contain lower levels. The researchers in the latest study noted that “organic products were significantly more likely to demonstrate higher levels of both cadmium and lead.”
The study didn’t include the brand names of the products tested, and Frame says that “doesn’t matter much” since there’s a high degree of variability from batch to batch, even within the same brand. “If there’s a product that’s high today, next year could actually be one that’s very low,” she says, which is why focusing on limiting your overall intake is the takeaway message.
If you have concerns about your health and heavy metal intake, Corlin suggests reaching out to your health care provider. “Everyone’s health risks are going to depend on their own health profile, and it’s always a good idea to talk to your doctor if you have any specific concerns,” she says.
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