One A Day

One A Day (sometimes referred to as One-A-Day) is a product family of multivitamins produced by the Bayer corporation. Introduced in 1940, One A Day was originally developed by Miles Laboratories. Bayer currently markets fifteen products in the One A Day line, listed below:

Bayer had previously heavily marketed a "WeightSmart" brand, but this was eventually discontinued after the United States Federal Trade Commission recovered $3.2 million (as part of $25 million settlement) from Bayer, alleging that Bayer had falsely claimed that the product led to weight loss.

One-A-Day Women's multivitamin was tested by ConsumerLab.com in their Multivitamin and Multimineral Supplements Review of 38 of the leading multivitamin/multimineral products sold in the U.S. and Canada. This product passed ConsumerLab's test, which included testing of selected index elements, their ability to disintegrate in solution per United States Pharmacopeia guidelines, lead contamination threshold set in California Proposition 65, and meeting U.S. Food and Drug Administration (FDA) labeling requirements.