February 20, 2013
Potency of Vitamin D Supplements Vary Greatly From Labels

Portland, OR—The vitamin D supplements sitting on pharmacy shelves often are not at the potency level they claim.

That’s according to a research letter published recently in JAMA Internal Medicine that found the amount of vitamin D in OTC and compounded supplements does not necessarily match the amount listed on the label. In fact, the analysis by researchers from the Kaiser Permanente Center for Health Research in Portland, Oregon, found that the amount of vitamin D in the supplements ranged from 9% to 146% of the advertised amount.

Variation not only existed among different brands and manufacturers but even among different pills from the same bottle, the researchers note.

“We were surprised by the variation in potency among these vitamin D pills,” said lead author Erin S. LeBlanc, MD, MPH. “The biggest worry is for someone who has low levels of vitamin D in their blood. If they are consistently taking a supplement with little vitamin D in it, they could face health risks.”

So how can pharmacists advise customers looking for vitamin D supplements? The researchers came up with a possible answer.

Testing a bottle from a manufacturer participating in the quality verification program operated by the U.S. Pharmacopeial Convention (USP), the researchers said they found that the amount of vitamin D in those pills was more accurately depicted on the label than others.

“The USP verification mark may give consumers some reassurance that the amount of vitamin D in those pills is close to the amount listed on the label,” LeBlanc said. “There are not many manufacturers that have the USP mark, but it may be worth the extra effort to look for it.”

For the study, researchers tested 55 bottles of OTC vitamin D from 12 different manufacturers and purchased at five different locations in Portland. The compounded vitamin D was made by a compounding pharmacy in Portland. Analysis was conducted by an independent laboratory in Houston.

“Because vitamin D insufficiency can be harmful to health, supplementation is often prescribed,” the research letter authors write. “However, the Food and Drug Administration (FDA) does not regulate vitamin D supplements, so potency may not be well evaluated. In a recent trial examining vitamin D in menopausal women, we found that compounded vitamin D3 (cholecalciferol) supplements varied significantly in potency. Only one-third of our compounded study pills met US Pharmacopeial (USP) Convention standards, which require that compounded pills contain 90% to 110% of the active ingredient.”

U.S. Pharmacist Social Connect