One A Day

Part of Bayer

https://www.oneaday.com Est. 1940 (86 years)

One A Day is a well-established brand in the multivitamins category, founded in 1940 and owned by parent company Bayer. The brand holds GMP certification, indicating adherence to good manufacturing practices, but lacks third-party testing certifications. Notably, One A Day has received a high number of FDA adverse event reports, totaling 442, which may raise concerns among potential consumers.

Red Flags

⚠High number of FDA adverse event reports (442)
⚠No third-party testing certifications found

Verified Strengths

✓Established brand — operating since 1940 (86 years)

Certifications

GMP Certified

FDA Record

Warning Letters

Recalls

442

Adverse Reports

How We Calculated This Score

Every brand starts with a baseline score of 70/100.

Points added for: Third-party certifications (NSF +15, USP +15, Informed Sport +10), publishing lab results (+10), clean FDA record (+10), 10+ years in business (+10), organic certification (+5).

Points deducted for: FDA warning letters (-25), product recalls (-20), high adverse events (-15), no third-party testing (-15), proprietary blends (-10), no GMP (-10).

Score is capped at 0-100. Grade and risk level are derived from the final score.

All data sourced from FDA.gov, NSF.org, USP.org, and publicly available brand information. Last updated: 3/20/2026.