Cadmium

You may want to put down that post-workout Muscle Milk.

Consumer Reports, a monthly review of consumer products and services, recently found that three popular protein drinks were packing more than just chocolate.

EAS Myoplex Original Dark Chocolate Shake and two versions of Muscle Milk chocolate drinks had high levels of arsenic, cadmium and lead.

Consumers Union tested three servings' worth of protein drinks -- a typical amount people drink in one day.

Andrew Shao, senior vice president of scientific and regulatory affairs at the Council for Responsible Nutrition, a supplement industry group, told Consumer Reports that protein powders and drinks are a safe option, even for teens and pregnant women -- groups frequently targeted for nutrition boosting, NPR reported.

But federal regulations don't generally require that protein drinks and other dietary supplements be tested before they are sold to ensure that they are safe, effective and free of contaminants, Consumer Reports noted.

"Most consumers and even many doctors don't realize that in this country we're left to simply trust the manufacturer to decide what level of quality and safety they'll provide," Pieter Cohen, an internist at Cambridge Health Alliance and author of a recent New England Journal of Medicine article on contaminants in dietary supplements, told Consumer Reports.

Cadmium is a metallic element. It has primarily been used in paints, coatings and batteries. Exposure in humans can cause significant kidney and lung damage.

Arsenic and lead are also naturally occurring metallic elements that have varieties of uses in industry from insecticides to electronics. But when consumed, they can cause cancer and brain damage.