You may be getting more than you bargained for with over-the-counter supplements, study finds

Woman taking vitamins and supplements
Many dietary supplements contain unapproved and unregulated pharmaceutically active ingredients, according to a recent study. 
(Tom Merton / Getty Images)

You’ve seen the ads for the pill that promises to make you skinny without having to diet or exercise, or for the supplement that claims it will make you the envy of the other weightlifters at the gym.

Their labels say they are all-natural and safe. But are they really?

Not necessarily, new research suggests.

In fact, hundreds of these products contain unregulated and unapproved pharmaceutically active ingredients, and that presents “a serious public health concern,” according to a study published this month in JAMA Network Open.


Researchers from the California Department of Public Health found that, from 2007 to 2016, 776 products marketed as dietary supplements contained hidden active ingredients that are unsafe or unstudied. One of them was dapoxetine, an antidepressant that is not approved for use in the United States. Another was sibutramine, which was banned from the U.S. market in 2010 because of cardiovascular risks.

“It’s mind-boggling to imagine what’s happening here,” said Dr. Pieter Cohen, an associate professor of medicine at the Cambridge Health Alliance in Massachusetts. Cohen wasn’t involved in the study but wrote a commentary published alongside the research.

The California researchers based their findings on an analysis of a Food and Drug Administration database that identifies “tainted” supplements. Being tainted or adulterated means the product contains active ingredients not listed on the label that fly under the FDA’s radar.

The agency considers dietary supplements — including vitamins, minerals and botanicals — to be foods rather than drugs. They are not intended to treat or prevent disease and are not subject to the premarket safety and efficacy testing that are required of new medicines.


The FDA database tracked problems that emerged during “post-market surveillance,” after the supplements were already in consumers’ medicine cabinets. These problems could include instances of adverse events or other consumer complaints.

Of the adulterated products, nearly 46% were marketed for sexual performance, 41% for weight loss and 12% for building muscle.

They contained ingredients like sildenafil, the active drug in Viagra, and ephedrine, a stimulant that has been banned from diet pills since 2004. Anabolic steroids, or ingredients like them, were found in 73 of the muscle-building supplements.

Nearly one-fifth of these supplements contained more than one unapproved ingredient.

“Adulterated dietary supplements have the potential to cause adverse health effects both on their own and also in combination with other medications an individual may be taking,” the study authors wrote.

Cohen described one such scenario: A patient with heart disease might be told to steer clear of prescription drugs for erectile dysfunction because they could interact with other medications and cause his blood pressure to fall to dangerously low levels. So instead, he turns to an over-the-counter supplement that’s marketed as “all-natural,” thinking it will not pose the risks he was warned about. “And that’s very worrisome,” Cohen said.

With an estimated 50% of Americans consuming some type of supplement, researchers note that the $35-billion industry is a big business.

Indeed, with somewhere between 50,000 and 80,000 supplement labels on the market, the finding of 776 tainted products represents a problem that is serious but not widespread, said Duffy MacKay, senior vice president for scientific and regulatory affairs at the supplement industry’s Council for Responsible Nutrition.


There’s little the FDA can or will do once a problem comes to light. Supplement recalls aren’t like food recalls, Cohen said. With supplements, the FDA can only notify a company that its products have unapproved ingredients; it’s up to the company to conduct a voluntary recall.

“The recall process itself has completely broken down as far as I can tell,” he said.

To reduce your risk, Cohen suggested looking for supplements with a single ingredient, because they’re less likely to contain secret, harmful ingredients. And never trust a supplement that definitively says it can improve your health.

That advice was echoed by MacKay, who said outrageous claims about weight loss or body building are red flags. So are ridiculous names like “Ball Refill” or “Weekend Prince.”

“There is such a difference between legitimate products and these products,” MacKay said.

Bluth writes for Kaiser Health News, an editorially independent publication of the Kaiser Family Foundation.