We purchased 15 protein powders and drinks mainly in the New York metro area or online and tested multiple samples of each for arsenic, cadmium, lead, and mercury. The results showed a considerable range, but levels in three products were of particular concern because consuming three servings a day could result in daily exposure to arsenic, cadmium, or lead exceeding the limits proposed by USP.
We found that three daily servings of the ready-to-drink liquid EAS Myoplex Original Rich Dark Chocolate Shake provides an average of 16.9 micrograms (µg) of arsenic, exceeding the proposed USP limit of 15 µg per day, and an average of 5.1 µg of cadmium, which is just above the USP limit of 5 µg per day. Concentrations in most products were relatively low, but when taking into account the large serving size suggested, the number of micrograms per day for a few of the products was high compared with most others tested.
The samples of Muscle Milk Chocolate powder we tested contained all four heavy metals, and levels of three metals in the product were among the highest of all in our tests. Average cadmium levels of 5.6 µg in three daily servings slightly exceeded the USP limit of 5 µg per day, and the average lead level of 13.5 µg also topped the USP limit of 10 µg per day. The average arsenic level of 12.2 µg was approaching the USP limit of 15 µg per day, and the average for mercury was 0.7 µg, well below the USP's 15 µg-per-day limit. Three daily servings of Muscle Milk Vanilla Crème contained 12.2 µg of lead, exceeding lead limits, and 11.2 µg of arsenic. A fourth product, Muscle Milk Nutritional Shake Chocolate (liquid), provided an average of 14.3 µg of arsenic per day from three servings, approaching the proposed USP limit.
Cadmium raises special concern because it accumulates in and can damage the kidneys, the same organs that can be damaged by excessive protein consumption. And it can take 20 years for the body to eliminate even half the cadmium absorbed today.
"This is a highly toxic metal, and while there are some cases where decisions have to be weighed against relative risks, accepting that you have to be exposed to any cadmium at all in your protein drink after your workout is definitely not one of them, " says Michael Harbut, M.D., director of the Environmental Cancer Initiative at the Karmanos Cancer Institute in Royal Oak, Mich.