Heavy Metals Found in Chocolate: Study Sheds Light on Lead, Cadmium in Some Products

A third of dark chocolate contains heavy metals, according to new data from Consumer Reports (CR).

Dark chocolate is often touted for satisfying a sweet tooth while providing some health benefits. It also often has less sugar than its milky counterpart, making it a favorite sweet treat for those looking to lower their sugar intake.

However, new Consumer Reports (CR) research from October found that a third of dark chocolate contains lead and cadmium.

“Our studies focused on two heavy metals, cadmium and lead, because the literature and information out there indicated that these two heavy metals when found at concerning levels, present the most concerning risk in chocolate products,” James E. Rogers, director and acting head of product safety testing at Consumer Reports, told Health. 

Heavy metals can have negative effects on the respiratory, neurologic, digestive, cardiovascular, urinary, and immune systems. Research shows that these metals may have a carcinogenic and estrogenic function, which could alter immune cells and inflammatory markers. 

That said, Rogers doesn’t want the new research’s results to panic consumers.

“We are not advising against consuming chocolate in its various forms,” he said. “However, we are providing this information to help consumers make safer choices.”

Here’s which chocolate varieties contain the most heavy metals, as well as best practices for choosing safe chocolate options.

Testing Chocolate Products for Heavy Metals

In the new report, Consumer Reports found some chocolates to “contain [heavy metal] levels above standard,” explained Marion Nestle, PhD, MPH, author and visiting professor of nutritional sciences at Cornell.

The research team tested 48 different products that were broken into the following categories:

• Cocoa powder
• Chocolate chips
• Milk chocolate bars
• Mixes for brownies, chocolate cake, and hot chocolate
• Dark chocolate bars 

Tested products came from name brands, including Hershey’s, Ghirardelli, and Nestlé. All products were purchased from national retailers like Costco, Target, Trader Joe’s, Walmart, and Whole Foods, as well as from specialty makers such as Droste and Navitas.

“Our testing methods are standard methods for reporting the presence and amounts of heavy metals in chocolate,” Rogers explained.

Researchers measured the amount of lead, cadmium, mercury, and arsenic in three samples of each product and averaged the results.

Because there currently are no federal limits for how much lead and cadmium most foods can have, the researchers used California’s standard maximum allowable dose levels (MADL) as their standard.

The MADL for lead is 0.5 micrograms per day; cadmium is 4.1 mcg per day in food.

While every product (milk and dark chocolate) that was tested had detectable amounts of lead and cadmium, the research team found that dark chocolate had higher levels of each metal.

Nestle explained that both lead and cadmium can affect the brain and nervous system, meaning awareness of these heavy metals entering the body is key.

Finding Chocolate That Doesn’t Contain Heavy Metals

According to Nestle, there is no way for consumers to ensure that the chocolate they eat does not have heavy metals in it. But, there are still certain tips to keep in mind.

Because levels of metals are higher in dark chocolate, she recommends choosing milk chocolates and options that are lower in cocoa.

“It’s always a good idea to vary what you eat,” Nestle explained. “But this situation calls for government regulation, big time. Write your congressional representatives and complain to the FDA.”

Rogers agreed. He noted that certain demographics are especially sensitive to heavy metal consumption, and should take extra caution when picking out a chocolate bar to enjoy.

“Pregnant people and kids should totally avoid dark chocolate bars and other chocolate products with lead or cadmium in our tests,” he said. “Heavy metals pose the highest risk to young children and the developing fetus of pregnant people.”

Rogers stressed that both manufacturers and the FDA, which oversees chocolate, should require testing of incoming ingredients and final products and remove these products before shipping to retail outlets.

The new CR research states that manufacturers can work to reduce heavy metals in their products in various ways, including:

• Using chocolate from areas that have low levels of cadmium in the soil
• Improving cocoa harvesting, processing, and cleaning procedures 

But until better processes and regulations are in place, Rogers said consumers should remain conscientious of what they eat. 

“It may not be possible to avoid all dietary exposure to heavy metals, because there are other, possible sources of these contaminants in your diet,” he said. “However, our goal is to help consumers reduce their total exposure to heavy metals by providing information such as this study.”