In pills from bottles made by a single manufacturer, but in different lots, the researchers found potencies as low as 9 percent and as high as 140 percent of the listed dose. They averaged the dosages of five pills from each bottle and found that only two-thirds met the U.S. Pharmacopeial Convention standard.

 

 

Pills from the bottle of the one manufacturer that was verified by the convention averaged 101.7 percent of the listed dosage, although the potency varied considerably from pill to pill.

 

 

The lead author of the study, Dr. Erin S. LeBlanc, a researcher at Kaiser Permanente in Portland, recommended looking for the U.S. Pharmacopeial Convention seal when shopping for vitamins. “If you have a bottle with the U.S.P. stamp on it,” she said, “you can feel reassured that what’s listed on the label is actually in the bottle.”

 

 

The researchers had become curious after testing vitamin D supplements that were being given to women participating in a study regarding the supplements' efficacy when used during menopause. The amount of variance in the prescribed pills, according to their research letter, led them to begin testing over-the-counter varieties as well.

 

 

 

 

- Overall, researchers say that they discovered that only one-third of the pills that they were giving to women in their initial trial met U.S. standards for potency.

- U.S. standards are determined by the the U.S. Pharmacopeial Convention, and state that compounded pills, such as the ones that were being used in the initial trial, must contain between 90 percent and 110 percent of the active ingredient listed on the label.

- Dr. Erin LeBlanc , who is one of the authors of the study and an endocrinologist at the Kaiser Permanente Center for Health Research in Portland, Ore., told the media that her team found that "the potency of these vitamin D supplements varied widely," as quoted by USA Today.

- The amount of actual vitamin D in any one of the supplements that the team tested ended up being between 9 percent and 140 percent of the actual amount listed on the packaging.

- When five pills were tested and the results averaged together, the results often were closer to being 100 percent of the promised dosage, but individual pills may contain too much or too little of the supplement to be effective.

- The concern, according to the team, is that those taking over-the-counter vitamin D supplements to treat a known deficiency may not get enough of it to actually help if the pills do not contain the amount of the supplement that is claimed on the labels.

 

 

 

 

(Article source: nytimes.com; news.yahoo.com)

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