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What's in That Dietary Supplement?

Experts urge consumers to use caution after studies find unexpected ingredients.

Supplements on store shelves.

Some dietary supplements contain pharmaceutical ingredients and unapproved stimulants, according to two studies recently published in the Journal of the American Medical Association.

It’s another reason people who take prescription medication should discuss any supplements they take with their doctor, several experts said in the Wall Street Journal. According to one of the studies, the FDA found 776 “adulterated supplements,” often in products marketed for sexual enhancement, weight loss and muscle building.

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Dietary supplements are not regulated by the federal government in the same way that prescription medicines are, so consumers should be careful when considering vitamins, minerals, herbals or other supplements. Even when supplements are not tainted with unexpected ingredients, they can be a bad mix with medications, changing the way the medicine works, according to guidance from the FDA.

And plenty of people take supplements. In a large U.S. study, about half of Americans said they used supplements. A 2018 British study found that one-third of older people were taking herbal supplements along with prescription medicines.

With supplements, caution is the best advice for everyone, including patients who have rare and serious diseases, said Deirdre Smith, CSL Behring’s Associate Director for Medical Information in North America.

“It’s always important for a patient to discuss all the medications and supplements they are taking with their doctor or pharmacist and to ask specifically about known side effects and interactions of the supplement,” she said.