Vitamin D Pill Variability Hints at Poor Quality Control

The vitamin D that people buy in a pharmacy or health food store may not deliver what it promises. Researchers at Kaiser Permanente Center for Health Research in Portland, Oregon, purchased 55 bottles of vitamin D3 from 12 different suppliers. The labeled doses ranged from 1,000 to 10,000 IU per pill, but when the scientists had them analyzed they discovered a big discrepancy in potency.
Some pills had only 9% of the labeled dose while others actually contained extra, up to 140% of the amount specified. Even pills from the same lot varied from 57% to 138%. These were presumably manufactured on the same production line at the same time, suggesting that quality control was abysmal. Because the manufacturers of vitamins and other dietary supplements are not closely monitored by the Food and Drug Administration, this worrisome discovery could just be the tip of the iceberg.
[JAMA Internal Medicine, online, Feb. 11, 2013]