Consumer Reports found dangerous heavy metals in chocolate from Hershey’s, Theo’s, Trader Joe’s and other popular brands. These are the chocolates that had the most metals and some that are safer.
By Kevin Loria
Data visualizations by Andy Bergmann
For many of us, chocolate is more than just a treat. It lifts our spirits, gives us energy, rewards us after a hard day and is our favorite Christmas gift.
People also choose dark chocolate in particular for its potential health benefits, thanks to studies suggesting its rich supply of antioxidants may improve heart health and other conditions, and for its relatively low sugar levels. In fact, more than half of the participants in a recent survey by the National Confectioners Association described dark chocolate as the “best for you” candy.
But this “healthier” chocolate has a dark side. Research has found that some dark chocolate bars contain cadmium and lead, two heavy metals linked to a number of health problems in children and adults.
The chocolate industry has been looking for ways to lower those levels. To see just how risky these favorite treats are, Consumer Reports scientists recently measured the amount of heavy metals in 28 bars of dark chocolate. They detected cadmium and lead in all of them.
Heavy metals in dark chocolate
CR tested a mix of brands, including smaller ones like Alter Eco and Mast and more well-known ones like Dove and Ghirardelli.
In the case of 23 of the tablets, eating just one ounce a day would put an adult above a level that public health authorities and CR experts say may be harmful for at least one of those heavy metals. Five of those tablets exceeded those levels for both cadmium and lead. Learn more about how CR tested dark chocolate (PDF).
That is somewhat risky. Constant and prolonged exposure, even in small amounts, to heavy metals can cause various health problems. The danger is greatest for pregnant women and young children, because metals can cause developmental problems, affect brain development and reduce IQ, says Tunde Akinleye, a CR food safety researcher who led this testing project.
“But there are risks for people of any age,” he says. Frequent lead exposure in adults, for example, can cause nervous system problems, high blood pressure, immune system suppression, kidney damage, and reproductive problems. Although most people don’t eat chocolate every day, 15% do, according to market research company Mintel. Even if you don’t eat chocolate often, lead and cadmium can be a cause for concern. They can be present in many other foods, such as sweet potatoes, spinach, carrots, and small amounts from various sources can reach dangerous levels. That’s why it’s important to limit exposure whenever possible.
Still, Akinleye says there’s no need to give up chocolate entirely. He adds that while most of the chocolate bars tested by CR had worrying levels of lead, cadmium, or both, five of them had relatively low levels of both metals. “This shows that companies can make products with lower amounts of heavy metals and that consumers can find safer products that they like,” he says.
In addition to choosing dark chocolates wisely, there are other steps you can take to continue enjoying chocolate safely.
The dark side of cocoa
Chocolate is made from the cocoa bean, which has two main components: cocoa solids and cocoa butter. Together they are called cacao or cocoa.
Dark chocolate’s reputation as a relatively healthy treat is largely due to the cocoa solids. These are full of flavonols, antioxidants related to improving the functioning of blood vessels, reducing inflammation and lowering cholesterol. Also, dark chocolate has less sugar and more fiber than milk chocolate, and it contains magnesium and potassium. Unfortunately, heavy metals, especially cadmium, are hidden in cocoa solids. That’s why it’s hard to balance the risks and benefits of dark chocolate.
Some of the same concerns may extend to products made with cocoa powder, which is essentially solid pure cocoa, such as hot cocoa and brownie and cake mixes, although they do contain varying amounts of cocoa and possibly heavy metals.
Dark chocolate tends to contain more heavy metals than milk chocolate, probably because of its higher cocoa content. There’s no official limit, but dark chocolates typically have at least 65% cocoa by weight, says Michael J. DiBartolomeis, a toxicologist and former California Department of Public Health official who has researched heavy metals in chocolate.
Eliminate lead and cadmium
To further complicate matters, it appears that lead and cadmium get into cocoa in different ways, which means each requires a different type of correction, DiBartolomeis says.
Between 2019 and 2022, he and other researchers studied how metals could contaminate cocoa, as part of a settlement for a lawsuit against chocolate makers brought by As You Sow, an organization that lobbies for corporate responsibility. As You Sow had previously found high levels of lead and cadmium in some chocolates.
The researchers found that cacao plants absorb cadmium from the soil and that the metal accumulates in the cacao beans as the tree grows. This is similar to the way heavy metals contaminate other foods.
But it seems that the lead gets into the cocoa after the harvest. The researchers discovered that the metal was normally found in the outer shell of the cocoa bean, not in the bean itself. Also, lead levels were low soon after the beans were picked from the pods, but increased as the beans dried in the sun for days. During that time, lead-filled dust and dirt accumulated on the grains. “We picked up kernels in the ground that were heavily loaded with lead in the outer shell,” DiBartolomeis says.
Due to the different pathways by which cadmium and lead reach chocolate, addressing contamination from those metals requires different solutions.
In the case of lead, that will mean changes in harvesting and manufacturing practices, says Danielle Fugere, president of As You Sow. These practices could include minimizing soil contact with the grains when they are in the sun, and drying them on clean tables or tarps away from roads or with protective covers, so that lead-contaminated dust does not fall on them. Another option is to find ways to remove metal contaminants when grains are cleaned in factories, Fugere says.
Solving the cadmium problem is more difficult, but possible, DiBartolomeis says. Careful breeding or genetic engineering of plants so that they absorb less cadmium could help, although it could take several years. Other possible options are to replace older cacao trees with younger ones, because cadmium levels tend to rise as plants age, and to remove or treat soil known to be contaminated with cadmium.
A safer chocolate
DiBartolomeis says that more immediately, chocolate makers should inspect cocoa-growing areas for cadmium levels and favor beans from places with lower levels. If necessary, they should mix beans from areas with higher levels of cadmium with ones with lower levels, as some manufacturers now do. Alex Whitmore, CEO of Taza, which makes one of the products with the lowest levels of both metals in CR tests, says that’s what his company does, mixing beans from “different origins to ensure that the final product” have lower levels.
The National Confectioners Association, which funded research on heavy metals in chocolate as part of the As You Sow deal, says that “a reduction in lead can be expected within the first year of implementing the new handling practices,” though it says that cadmium reduction may take longer.
Some manufacturers with higher levels of metals in our tests said their products are below the levels established by the agreement. Others stated that metals are found naturally in the soil and that they are taking steps to try to reduce them. Alter Eco, Endangered Species, Theo, and Trader Joe’s did not respond.
Taking steps to reduce heavy metals in cocoa may pay off: After all, CR’s test results show that while heavy metal contamination is common, it’s not inevitable.
In addition to choosing products with lower levels of lead and cadmium, there are other steps that can help reduce risks. In fact, DiBartolomeis says that while she cautions pregnant women and children against eating dark chocolate, she doesn’t advise most people to forgo it, but rather to be aware of the risks and not overindulge.
Best Ways to Eat Dark Chocolate
Calculating the exact amount of dark chocolate that is risky to eat is tricky. This is because heavy metal levels can vary, people have different levels of risk, and chocolate is just one potential source of heavy metal exposure. But experts say that if you take the risks into account, dark chocolate can be enjoyed while minimizing the potential harm.
Choose dark chocolates with the lowest levels of heavy metals. Five chocolates, one from Mast, one from Taza and one from Valrhona, and two from Ghirardelli, were found in CR’s tests to have relatively low levels of both lead and cadmium. Another eight have lower levels for lead only, and another 10 for cadmium only. Only five tablets, one from Green & Black’s and one from Lily’s (owned by the Hershey company) and one from Trader Joe’s, and two from Theo, had higher levels of both heavy metals.
Treat chocolate like a treat. A single ounce of one of the chocolates with the highest levels of cadmium and lead in CR tests is unlikely to cause immediate harm. The risk comes with frequent consumption over time. Heavy metals are also found in other foods, including many that are more nutritious and important for a healthy diet, such as carrots, sweet potatoes, and spinach. So it’s best to only eat dark chocolate once in a while. “Having a serving a few days a week, especially with a product that has lower levels, means you can eat dark chocolate without undue worry,” says CR’s Tunde Akinleye, who oversaw the chocolate trials.
Try dark chocolates with lower cocoa percentages. If you are considering a tablet that has not been tested by CR, so the heavy metal content is unknown, you might opt for a product with 70% dark chocolate instead of 80%, for example, or a tablet with a 65% instead of 70%. It’s not a foolproof measure, but CR’s tests, as well as those done by other organizations, suggest that cadmium levels tend to increase with the percentage of cocoa. (Lead levels don’t seem to be as closely tied to cocoa percentage.)
Alternate with milk chocolate. Cocoa levels are lowest in e l milk chocolate than dark chocolate, so milk chocolate tends to have lower levels of heavy metals, says DiBartolomeis. But that doesn’t mean you can eat it with abandon: it has a lot more added sugars. So it’s best to eat both types of chocolate only once in a while, not every day.
Don’t assume that organic dark chocolates are safer. In CR’s tests, they were just as likely as other products to have concerning levels of heavy metals.
Don’t give too much dark chocolate to children. Dark chocolate isn’t a big hit with most kids, which is fine, considering that the younger you are, the greater the threat from heavy metals. Pregnant women should also limit their consumption.
Think about your total consumption of chocolate. We have not tested cocoa powder, hot cocoa mixes, or other chocolate desserts for heavy metals. But they also contain cocoa solids, so they could contribute to your heavy metal intake.
Follow a balanced diet. Changing the foods you eat can help you avoid overconsumption of heavy metals from other sources. Grapes, apples, green tea, and other healthy foods can provide some of the same flavonols as chocolate. Additionally, this can help provide a variety of nutrients that can help offset some of the damage heavy metals cause. Among them are calcium, iron, selenium, vitamin C and zinc.
Consumer Reports is an independent, nonprofit organization that works side by side with consumers to create a fairer, safer, and healthier world. CR does not endorse products or services, and does not accept advertising. Copyright © 2023, Consumer Reports, Inc.
Consumer Reports has no financial relationship with the advertisers on this site. Consumer Reports is an independent, nonprofit organization that works with consumers to create a fair, safe, and healthy world. CR does not endorse products or services and does not accept advertising. Copyright © 2023, Consumer Reports, Inc.