Vitamin D labels can be misleading
Research published in the journal JAMA Internal Medicine found that the amount of vitamin D listed on a bottle’s label often differs significantly from the amount of the vitamin actually found in the pills inside.
Researchers tested 55 bottles of over-the-counter vitamin D supplements from 12 different manufacturers, all of them bought from stores in Portland, Oregon. After testing the supplements, they found that the amount of vitamin D in the supplements ranged from 9 to 146 percent different from the amount listed on the bottle. Not only that, some of the pills within the same bottle had varying amounts of vitamin D.
There is no formalized regulatory system for over-the-counter supplements in the United States. Manufacturers can voluntarily submit their supplements to the U.S. Pharmacopeial Convention (USP) verification program and receive a USP verified stamp on their label’s packaging. In light of the findings, researchers suggest that consumers check for the USP label before buying vitamin D supplements.