<http://www.usatoday.com/story/news/nation/2013/02/11/vitamin-d-supplement-labeling/1909603/>

Vitamin D doses often don't match labels, study says

What's in your vitamin supplement? It could be more or less than you think,
according to the latest study to show that what's on a supplement label is
not necessarily what's in the bottle.

Researchers who tested vitamin D pills sold in stores found they contained
from 9% to 140% of the doses listed on labels, according to a research
letter published Monday in JAMA Internal Medicine. Though none of the pills
was likely to be dangerous, some contained too little of the vitamin to
effectively treat someone with a deficiency, the researchers say.

"We found the potency of these vitamin D supplements varied widely," says
Erin LeBlanc, an endocrinologist who led the study at the Kaiser Permanente
Center for Health Research in Portland, Ore.