A new study analyzed the ingredients in 23 popular protein shakes and powders and revealed a concerning finding.
Lead.
Consumer Reports conducted the investigation.
Protein powders "still carry troubling levels of toxic heavy metals," the investigation found.
It's a growing issue.
"Our latest tests of 23 protein powders and ready-to-drink shakes from popular brands found that heavy metal contamination has become even more common among protein products, raising concerns that the risks are growing right alongside the industry itself," the site noted.
Consumer Reports found more lead than experts "say is safe to consume in a day" in more than two-thirds of the products, "some by more than 10 times."
“It’s concerning that these results are even worse than the last time we tested,” said Tunde Akinleye, the lead researcher, told Consumer Reports.
The concerning lead levels were also found in plant-based products, according to CR.
"Dairy-based protein powders and shakes generally had the lowest amounts of lead," the site reported.
Consumer Reports did caution that "any of these powders are fine to have occasionally, and even those with the highest lead levels are far below the concentration needed to cause immediate harm."
Some protein product companies pushed back to CBS News.
Huel's Head of Nutrition, Rebecca Williams, said the company's products "fully comply with international food safety regulations" and are "completely safe to consume."
"Trace amounts of lead occur naturally in some food ingredients," she said to CBS News. "The level reported by Consumer Reports for Huel Black Edition is well within internationally recognised safety limits and poses no health risk. We carry out regular testing with accredited independent laboratories to ensure our products consistently meet the highest standards of quality and safety."
The U.S. Food and Drug Administration has been increasingly educating the public on lead levels in other food items.
"The U.S. Food and Drug Administration (FDA) issued guidance for industry on the action levels for lead in processed food intended for babies and young children," the FDA wrote in January.