You might want to think twice before consuming that post-workout protein shake you’re so keen on. A new study from national advocacy group Clean Label Project evaluated 134 of the top-selling protein powders (according to data from and Nielsen) and the results were not pretty. A third-party organization, Ellipse Analytics, who ran the scientific tests, found that 70 percent of them contained lead concentrations of at least four micrograms per kilogram.

To put that amount in perspective, the Joint Expert Committee on Food Additives (JECFA) recommends that you consume no more than 25 micrograms/kilogram a week. If you drink one of these beverages daily, you’d reach this amount easily, plus the additional 20-30 micrograms you’re estimated to consume from other normal food sources. That’s near double the permissible amount, which  is scary since lead toxicity can lead to changes in neural behavior and abdominal pain.

Clean Label Project

Other metals including cadmium mercury and arsenic were also found in varying amounts, as well as the toxin bisphenol A (BPA). All of these substances are known to have toxic effects when consumed in large amounts.

If you’re looking for tips on how to source safer protein powders, here’s some advice: None of the egg-based protein powders evaluated contained lead. Plant-based protein powders also had more heavy metals present than non-plant-based ones. This is likely because of soil contamination from where those plants are sourced.

Of all the brands evaluated, Biochem, Jarrow, Puori, Performix, and Reservage Nutrition rated highest in quality, while Quest Nutrition, Nature’s Best, Sunwarrior, Vega, and Garden of Life were the among the worst. So that’s something you might want to keep in mind the next time you’re perusing the supplement aisle of your local supermarket.

You can check out the infographic below and read the study in its entirety here for more on these findings.

Clean Label Project

Header image courtesy of Shutterstock.

Jessica is an Associate Editor at Chowhound. Follow her on Twitter @volume_knob for updates on snacks and cats.
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