Why Were High Levels of Toxic Metals Found in Protein Powders?

For the study, researchers took 160 products from 70 of the most popular protein powder brands. They then shipped samples of each protein powder to an independent laboratory, where they were analyzed for several heavy metals, along with other potential contaminants. The researchers found that 47 percent of the samples had levels of lead and cadmium that exceeded guidelines set by California’s Proposition 65, a law that requires companies to warn consumers about significant exposures to chemicals that could cause birth defects, cancer, or reproductive issues.

While it’s worth noting that Proposition 65 guidelines are significantly lower (aka stricter) than standards set by the Food and Drug Administration (FDA), more than 20 percent of the powders contained heavy metal levels that were twice as high as Proposition 65 guidance. There has also been no established safe level of lead exposure.

The researchers found that chocolate protein powders contained four times more lead than their vanilla counterparts, and some chocolate powders contained up to 110 times more cadmium than vanilla powders.

Given how popular chocolate-flavored protein powders are, it’s understandable to have concerns. After all, lead is associated with brain damage and developmental issues in children, and cadmium can raise the risk of developing certain cancers. Here’s what food safety experts want you to know.

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Why were these toxic metals found specifically in chocolate protein powder?

This isn’t the only recent report to detect the presence of lead and cadmium in chocolate. In October 2023, Consumer Reports released the results of a report that found 16 of the 48 chocolate products the nonprofit tested from various companies had potentially harmful levels of lead, cadmium, or both.

But food safety and nutrition experts aren’t shocked that these metals have turned up in another range of chocolate products. “Finding lead and cadmium in chocolate is not surprising,” says Gabriel Keith Harris, PhD, professor of food science at North Carolina State University. “This has been reported since at least the late 1980s.” He also points out that lead and cadmium are found in a wide range of fruits and vegetables, too.

“Lead and cadmium often enter the food supply through environmental contamination,” says Leigh A. Frame, PhD, associate director of the George Washington University Resiliency & Well-Being Center. “These metals can be absorbed by plants from contaminated soil or water, and cocoa, a key ingredient in many chocolate protein powders, is particularly susceptible due to its growth conditions.”

Processing and storage after the cocoa is harvested can introduce or concentrate those metals, Frame says. “For protein powders, additional risks may come from the processing of plant-based proteins, which can retain higher levels of contaminants, and from flavoring agents or other added ingredients,” she adds.

Harris stresses that Prop 65 levels are stringent, adding, “this means that ‘exceeding Prop 65 limits’ is a lot more likely than ‘exceeding FDA or European Union limits,’” he says. Something else to consider, per Felicia Wu, PhD, a professor of food safety, toxicology, and risk assessment at Michigan State University. “This report did not reveal what the actual numbers are, and the Prop 65 recommendations are for amounts per day.” With that, Wu says it’s not clear how much protein powder the Clean Label Project assumes people eat per day. “Without this more detailed information, we cannot say what the real risk to human health is,” she says.

But the findings are still concerning and reinforce the need for stricter monitoring and quality control in food production, according to Frame. “The fact that nearly half of the protein powders tested exceeded Proposition 65 safety thresholds for heavy metals such as lead and cadmium highlights a gap in current safety standards,” she says. “While these products are popular among health-conscious consumers, they may inadvertently expose users to harmful contaminants, raising serious questions about ingredient sourcing and manufacturing practices.”

What happens next?

Unfortunately, the Clean Label Project didn’t reveal the names of the products the organization tested or which had lower levels of these metals. But Harris says the report findings highlight the need to determine how much lead and cadmium is in products like chocolate protein powder going forward.

“We should first work to understand whether the levels of lead and cadmium from chocolate and other plant products might cause harm to children or adults,” he says. “It’s important to consider the ‘dose’ received from the whole diet, not just a single food.”

It’s also crucial to explore how cadmium and lead levels in soil and water can be reduced so that less can get into the plants in the first place. “One way to do this is to remove lead- and cadmium-containing soil and replace it with soil that does not contain those minerals,” Harris says. “Another is to change the chemistry of the soil, so plants cannot absorb lead and cadmium as easily.” Still, Harris says that so far, no single method has shown to be a viable long-term solution to prevent these minerals from getting into plants in the first place.

Frame says the latest findings do highlight the need for industry-wide changes. “The presence of heavy metals in foods marketed as healthy underscores the need for robust safety standards, particularly for products like protein powders that are consumed regularly and often in high quantities,” she says. “Moving forward, there should be a greater emphasis on reducing contamination at every stage of production and ensuring that products marketed for health do not pose hidden risks.”