Toxins Found In Protein Powder—What Experts Want You To Know Before Making Another Shake
For those who struggle to get their proper daily intake of protein, protein powder has become a godsend. With so many brands, flavors, and products on the market, it’s easier than ever to boost your nutrition. The advent of both flavored and flavorless protein powders allows people to get creative in the kitchen, making everything from cosmic brownie protein bites to piña colada protein smoothies. Heck, I used to scoop some powder into my morning tea.
Registered dietitian and owner of Compass Nutrition, Adiana Castro, MS, RDN, CDN, agrees that protein powders are a quick and convenient way to increase your intake of this “superpower macronutrient” which, she says, “our bodies need to keep us full longer, reduce appetite, and maintain lean muscle, which can lead to weight management.”
However, powder lovers might want to rethink that double scoop next time you swing by your favorite smoothie place or whip up a shake at home. In a recent study conducted by Clean Label Project, a national nonprofit with the mission of bringing truth and transparency to food and consumer product labeling, almost half of the powders tested contained impurities—more specifically, they contained toxic metals. Yikes.
Clean Label Project tested 160 products from 70 of the top-selling protein powder brands and found that 47% of these products exceeded California Proposition 65 safety thresholds for toxic metals. Prop 65 is a law in California designed to protect state residents from harmful chemicals and it’s important to note that those regulations differ from FDA standards.
As Castro points out, “the FDA’s levels are based on the risk of acute or chronic lead and cadmium exposure from a particular food source.” In contrast, Proposition 65’s maximum allowable dose levels (MADL), she explains, “are intended to trigger warnings for consumers about overall exposure to harmful chemicals.”
In other words, consumers should be aware that a Proposition 65 warning doesn't necessarily indicate a product is unsafe by federal standards, but rather reflects California's uniquely stringent approach to chemical exposure notifications.
So what exactly do we need to know about this protein powder study?
Here's What The Study Found
All of the powders tested were subjected to screening for heavy metals and bisphenols, which are chemical compounds often used to produce plastics and resins. Varying levels of arsenic, cadmium, lead, and mercury were found. Not only did 47% of the products tested exceed California Proposition 65 safety thresholds for toxic metals, but 21% of the samples contained levels more than twice as high as those allowed under Proposition 65.
The study revealed significant variations in heavy metal contamination across different types of protein powders. Of note, organic protein powders showed higher levels of contamination, with 79% exceeding Proposition 65 levels for heavy metals. These organic options contained three times more lead and twice as much cadmium as their non-organic counterparts.
Plant-based protein powders also raised concerns, with 77% exceeding Proposition 65 levels for lead, compared to only 28% of whey-based powders. Plant-based options contained three times more lead than whey-based products.
Flavoring also played a role, as 65% of chocolate-flavored powders exceeded Proposition 65 levels. These chocolate-flavored options contained four times more lead and up to 110 times more cadmium than vanilla-flavored products.
Researchers found that whey or collagen based protein powders that are not chocolate-flavored contained the least amount of lead.
On a lighter note, Clean Label Project's study found great improvement in BPA and BPS levels when compared to findings from a similar study conducted in 2018. In 2018, 55% of powders tested were contaminated with BPA or BPS. This year's findings only found the contaminants in three out of 160 powders tested—a marked improvement.
According to the researchers, the main source of these contaminants comes from the soil where the ingredients are grown, as well as the packaging used for the products.
How Worried About These Toxins Should We Be?
Heavy metals in food products have become quite the topic amongst food safety experts and concerned citizens. And for good reason. “High levels of lead can cause long-term health problems in the brain, kidneys, and other organs,” Castro explains. “High levels of cadmium can cause cancer, kidney disease, and bone problems.” She does point out that the human body slowly excrete small amounts of heavy metals over time.
The Prop 65 MADL for lead is.5 micrograms total a day, from all sources. Those guidelines also state that, for sensitive groups such as pregnant women and children, there is no safe level of exposure to lead whatsoever. FDA regulations vary by food type, from an allowable.05 parts per million (ppm) in canned fruits and vegetables to an allowable 50 micrograms per liter in fruit juices.
When it comes to cadmium, the MADL is 4.1 micrograms per day, while the FDA regulations allow for amounts ranging from.1 ppm in leafy veggies to 2 ppm in shellfish.
Bisphenols, which include BPAs and BPSs, were banned in baby bottles and sippy cups over a decade ago, but they can still be found in many kitchen products and food packaging. They are known for causing metabolic problems, cancer, and developmental issues in children. However, the FDA maintains that BPA is safe at the very low levels that occur in some foods, which was determined to be 5 milligrams per kilogram body weight per day.
What Does This All Mean For You?
"The research on this issue is conflicting and remains an ongoing conversation," says Bridget Wood, RD, LD, CDCES. “While a 2020 study found that typical supplement use was unlikely to cause harm from heavy metals, a 2023 scientific statement by the American Heart Association (AHA) linked low-level exposure to metals like lead and cadmium with increased risks of heart disease, stroke, and more. The common thread between these findings? Both emphasize that the presence of these metals is environmental and largely beyond consumer control.”
But what about what we can control?
It's important to note that although the Clean Label Project study points to problematic issues with protein powder, it does not list the actual lead and cadmium levels that they detected, nor the brands that were tested.
“Without that critical piece of information, I can't tell if the amounts of metals detected are enough to cause human disease,” Castro tells us. “Unfortunately, without full transparency of the actual levels consumers could be confused and misled instead of gaining confidence and clarity.”
“The safest option would be eating protein from whole foods,” she says. “However, it is highly unlikely that you would be impacted by these toxic metals by ingesting low amounts of protein powder—like one protein shake or one serving size.”
If you're concerned, though, Castro recommends unflavored protein powders, looking for products tested by verified third parties such as NSF Certified for Sport or Clean Label Project, or even reaching out directly to your favorite brand for transparency about their sourcing, heavy metal levels, and safety practices.
The study also concludes with a list of brands that are Clean Label Project Certified. These include Ritual, Puori, Gorilla, Nutrabox, Wellbeing Nutrition, Oziva, and Genetic Nutrition.
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