Have you returned those cadmium-tainted Shrek glasses to McDonald's already? Your kitchen may still be tainted with toxic heavy metals — if you're a protein shake drinker.

That's right — some popular protein drinks are tainted with worrying levels of cadmium, lead, mercury — and even arsenic! That's according to Consumer Reports, which hired an independent lab to study 15 different protein shakes.

At NPR's health blog Shots, April Fulton quotes representatives from these shake companies, who say their own tests on their products showed lower levels of these heavy metals, and that their products are still "a safe option, even for teens and pregnant women."

I'm not willing to take the risk, however. As Fulton points out:

Cadmium can cause serious kidney damage, too much lead cause neurological problems, and we all know why arsenic is a mystery novelist's favorite poision, don't we?
Plus, I'm not tempted to drink weird, processed protein shakes when I can get protein deliciously from organic beans, good old tofu, and sustainable seafood. What is your favorite source of protein?

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