Vitamin D Supplements Tested for Quality
Researchers led by Erin S. LeBlanc, MD, MPH, of the Kaiser Permanente Center for Health Research in Portland, Oregon report that the amount and potency of vitamin D sold in over-the-counter supplements do not always match the information on their labels. However, they found that products with the USP verification mark are generally more accurately labeled than those without the mark.
It is estimated that more than 100 million Americans spend billions of dollars on dietary supplements and multivitamins annually, according to a recent editorial in the New England Journal of Medicine. However, the production and sale of these products remain unregulated by the U.S. Food and Drug Administration.
Vitamin D deficiency has recently been linked to certain health conditions like obesity and chronic diseases like diabetes and heart disease, leading some people to use over-the-counter supplements. However, the team’s analysis showed that supplemental vitamin D potency varies widely and many products contain various amounts, ranging from less than 10% to more than 100% of the amount listed on their labels. They also noted that these variations were found not only among different brands and manufacturers, but also among pills in the same container.
LeBlanc expressed that their biggest worry is for someone who is taking vitamin D consistently for a deficiency and is getting inadequate doses because of the poor quality of the products they bought.
An independent, nonprofit organization called the U.S. Pharmacopeial Convention sets public standards to ensure the quality of dietary supplements. For products to bear the USP verification mark manufacturers must pass the annual good manufacturing-practice audits and their products must pass the tests for purity, quality, and potency. Dr. LeBlanc and her colleagues found that one supplement with a USP Verified manufacturer mark in their sample gave more accurate labels than other bottles tested.
Kaiser Permanente. Vitamin D potency varies widely in dietary supplements, analysis finds. ScienceDaily.