Vitamin D supplements' potency varies widely

The amount of vitamin D in supplements can be anything from 9% to 146% of the stated dose, according to a research letter published in the JAMA Internal Medicine.1 Investigators from Kaiser Permanente tested 55 bottles of over-the-counter vitamin D supplement tablets from 12 different manufacturers using high performance liquid chromatography .

http://www.chromatographyonline.com/lcgc/Vitamin-D-supplements-potency-varies-widely/ArticleStandard/Article/detail/809102?ref=25