Labdoor analyzed 21 best-selling vitamin C supplements in the United States for vitamin C content and heavy metal (arsenic, cadmium, lead, mercury) contamination.
The majority of products (17 of 21) recorded vitamin C content within 10% of their label claims. However, 3 products deviated off their claims by at least 30%. Products ranged from having 60% less to 74% more than their label claims.
The lowest measured vitamin C level fell below the recommended daily allowances (RDAs) of 90 and 75 mg/day for men and women, respectively, needed to protect against vitamin C deficiency. The highest measured vitamin C level exceeded the established Tolerable Upper Intake Level (UL) of 2000 mg/serving for safe vitamin C intake.
All tested products passed heavy metal screens for cadmium, lead, and mercury.