Labdoor analyzed 27 best-selling zinc supplements in the United States for elemental zinc content and heavy metal (arsenic, lead, cadmium) contamination.
Products performed fairly well in label accuracy. More than two-thirds of the tested products were found to have actual amounts of elemental zinc within 5% of their label claims. 22 of 27 products contained more elemental zinc than claimed, averaging an excess of 4.4%. Elemental zinc content ranged from 2.3 mg to 59.9 mg per serving. 25 of 27 products, in one serving, met or exceeded the Recommended Dietary Allowances (RDAs) of 11 mg and 8 mg of zinc per day for men and nonpregnant women ages 19+, respectively.
11 of 27 products exceeded zinc’s Tolerable Upper Intake Level (UL) of 40 mg per day for healthy men and women ages 19+ in one serving. All products passed heavy metal screens for arsenic, lead, and cadmium indicating that 2 PPM or more of each heavy metal was not detected.
Collective data for this analysis relied on the analytical chemistry method, ICP-OES (Inductively Coupled Plasma - Optical Emission Spectrometry), to detect and quantify elemental zinc content and heavy metal (arsenic, lead, and cadmium) load.