Labdoor analyzed 75 best-selling multivitamin supplements in the United States, measuring levels of key vitamins (A, B-3, B-6, C, D, and folic acid), minerals (calcium, iron, magnesium, manganese, phosphorus, potassium, sodium, and zinc), fatty acids (total omega-3, EPA, and DHA), and heavy metals (arsenic, lead, cadmium, bismuth, antimony, and silver).

The products tested missed their vitamin label claims by an average of 22.6% and missed their mineral label claims by an average of 29.2%. Supplement labels most commonly overstated their claims for vitamins A and C, with 12 multivitamins (16%) containing at least 30% less vitamin A vs. their label claims and 21 multivitamins (28%) containing at least 10% less vitamin C vs. their label claims.

Samples of every multivitamin passed all six heavy metals assays. 11 products contained at least one artificial color (Blue 1, Blue 2, Red 40, Yellow 5, or Yellow 6). Labdoor scientists also identified benzoic acid and caramel color in three products and BHT (Butylated hydroxytoluene) in five products.