One A Day vitamins are made by Bayer, the German pharmaceutical and consumer health company, though the brand itself was created in the United States. Most One A Day products sold domestically are manufactured at Bayer’s own plants in the United States.
Bayer also operates vitamin manufacturing outside the US, including facilities in Germany, Switzerland, and Spain, and some One A Day products are sourced from those international plants. The FDA requires supplement labels to note the country of manufacture if it is outside the United States.
This article covers who owns One A Day, where its vitamins are actually manufactured, the brand’s founding history, and its recent 2025 rebrand.
So let’s get started.
Table of Contents
Who Owns One A Day?
One A Day is owned by Bayer, the German multinational pharmaceutical and consumer health company headquartered in Leverkusen, Germany. Current product information is available on One A Day’s official website.
Bayer reported sales of roughly 46.6 billion euros in fiscal year 2024 and employed around 93,000 people worldwide, making it one of the largest healthcare and life sciences companies on earth.
One A Day sits within Bayer’s consumer health division alongside other well known brands.
Bayer has owned One A Day since 1995, when it fully absorbed Miles Laboratories, the Indiana based company that originally created the brand and had operated as a Bayer subsidiary since 1979.
Where Are One A Day Vitamins Made?
Most One A Day vitamins sold in the United States are manufactured domestically at Bayer’s own facilities, including its main multivitamin plants in Elkhart, Indiana and Pennsylvania.
Bayer also manufactures vitamins internationally, including in Germany, Switzerland, and Spain, and some One A Day products sold in the US are sourced from these overseas facilities rather than domestic ones.
International production has grown to represent a meaningful share of Bayer’s overall US focused vitamin output in recent years.
Because manufacturing location can vary by specific product and even by production run, the most reliable way to confirm where a particular bottle was made is to check the label directly, since federal rules require the country of origin to be listed if a supplement is manufactured outside the United States.
When Was One A Day Founded?
One A Day was introduced in 1940 by Miles Laboratories, a pharmaceutical company founded in Elkhart, Indiana in 1884 by Dr Franklin L Miles. More on the brand’s origins is documented on Wikipedia.
Miles Laboratories also created other well known products including Alka Seltzer and Flintstones Vitamins before becoming a wholly owned Bayer subsidiary in 1979.
Bayer fully absorbed Miles Laboratories into its parent corporation in 1995, and the One A Day brand has operated under the Bayer name ever since.
Today the One A Day lineup includes more than a dozen formulas targeted at different life stages and health goals, from prenatal vitamins to formulas for adults over fifty.
What Changed With the 2025 One A Day Rebrand?
In October 2025, Bayer introduced a new brand identity for One A Day under the platform The ONE for you, aimed at making it simpler for shoppers to find the right multivitamin for their age and health goals.
The rebrand included new packaging, a refreshed logo, and updated messaging that began appearing at major retailers including Walmart, Target, Walgreens, CVS, and Amazon starting in September 2025. Bayer has said the transition across the full product lineup continues into 2026.
The rebrand did not change where or how the vitamins are manufactured. It focused on packaging clarity and marketing rather than the underlying formulas or production locations.
Is One A Day a Good Multivitamin?
One A Day is widely regarded as a reliable, budget friendly multivitamin, with many long term users on retailer review pages reporting years of consistent use without issues.
Reviewers frequently cite good value, wide availability, and a straightforward once daily dosing format as key strengths.
The most common complaints relate to tablet size, since some formulas are described as large and harder to swallow than gummy alternatives, along with occasional reports of stomach upset when taken without food.
Some reviewers also note a bright yellow tint to urine after taking the vitamins, which is a harmless and well known effect of riboflavin, or vitamin B2, being excreted in excess.
As with any multivitamin, One A Day is intended to fill nutritional gaps rather than produce a noticeable, immediate effect, and people considering a new supplement routine should talk to a doctor or pharmacist, particularly if they take other medications or have existing health conditions.
Frequently Asked Questions About Who Makes One A Day
Is One A Day made in the USA?
Most One A Day vitamins sold in the United States are made domestically at Bayer’s plants in Indiana and Pennsylvania. Some products are manufactured internationally in countries including Germany, Switzerland, and Spain, and the label will note this if it applies to that specific item.
Is Bayer a German or American company?
Bayer is a German multinational company headquartered in Leverkusen, Germany. It has owned the One A Day brand, which was originally created by an American company, since fully absorbing Miles Laboratories in 1995.
Who originally created One A Day vitamins?
One A Day was created in 1940 by Miles Laboratories, a pharmaceutical company based in Elkhart, Indiana. Miles Laboratories became a Bayer subsidiary in 1979 and was fully absorbed into the parent company in 1995.
How can I tell where my One A Day product was made?
Check the label on the bottle or box. US regulations require supplement companies to list the country of manufacture if a product was made outside the United States, so a domestic product will typically not carry a country of origin statement.
I am Jack Neel, a mechanical engineer, researcher, and writer. I created this website to share my knowledge about different brands and products with you. I research the manufacturers behind the brands and provide you with the information you need to make smart buying decisions.