Could your supplement be tainted?

    Exploring the issue of supplement adulteration.

    Quiz of the week!


    Morgan here, one of the research leads at Examine.

    One of the most common misconceptions we come across is that supplements are safe because they’re not prescription pharmaceuticals.

    Here are just a few supplement-related risks we’ve written about:

    But there’s another supplement-related concern that probably doesn’t get enough attention: undeclared ingredients. Specifically, the presence of undeclared drugs in dietary supplements.

    Are your supplements on drugs?

    In recent years, numerous professional athletes have tested positive for performance enhancing drugs (PEDs), only to claim they unknowingly took a dietary supplement secretly adulterated with that drug.

    In one high-profile case, MMA fighter Yoel Romero actually sued a supplement company, alleging that their product was responsible for his failed drug test and subsequent suspension from the sport.

    It’s easy to assume this is just a convenient alibi athletes use when they’ve been caught doping. I mean, it’s a bit more plausible than blaming your failed test on a CIA conspiracy (an actual excuse once given), but drugged-up supplements can’t be that common, right?

    Surprisingly, there seems to be some truth to it.

    That’s not to say all, or even most, athletes are being honest when they say a tainted supplement made them fail a drug test. But there is considerable research showing that supplement adulteration is a shockingly widespread issue.

    One of the most comprehensive papers on this topic was a 2022 review of 50 studies. More than 3,000 supplements were analyzed, sourced from all over the world, including the U.S., the U.K., Italy, Germany, and China. The findings were concerning, to say the least.

    In total, 28% of the tested supplements contained undeclared drugs.

    Now, that number might be somewhat inflated, given that researchers were likely seeking out supplements more prone to contamination. However, studies consistently find some degree of contamination is present in many different types of supplements from many different sources.

    Is that bad? It sounds bad.

    Perhaps some comfort can be taken in the fact that when adulterants are detected, they’re often in very small quantities. But make no mistake, some supplements have been found to contain concerning levels of drugs that can harm health.

    A notable example is sibutramine. Sibutramine was once prescribed for weight loss, until a large clinical trial found it increases the risk of heart attacks and strokes. As a result, the drug was pulled from the market.

    Except sibutramine didn’t exactly disappear from commercial circulation. Instead, it found its way into weight loss supplements, becoming one of the most commonly detected adulterants in dietary supplements, sometimes in higher doses than when the drug was prescribed.

    As previously noted, sibutramine is found almost exclusively in supplements marketed for weight loss, perhaps to make up for the ineffectiveness of the listed ingredients. To make matters worse, weight loss supplements have also been found adulterated with undeclared stimulants, laxatives, and SSRIs, which can be dangerous.

    Perhaps this explains why bad reactions to weight loss supplements send thousands of people to the emergency room every year in the U.S. alone.

    What other kinds of supplements are commonly adulterated?

    Some supplement types appear to be more commonly adulterated than others.

    Supplements for exercise performance seem especially dodgy, with the potential to contain a number of undeclared steroids, SARMs, and stimulants. Various preworkout supplements have been found to contain 1,3-dimethylamylamine (DMAA), a now-widely banned stimulant.

    Other more frequently tainted supplement types include those marketed for sexual health, joint pain, and cognitive function.

    In fairness, there isn’t much hard data establishing the actual health consequences of taking supplements contaminated with drugs, but that’s also kind of the problem — we don’t know enough. Adulterants come in a wide variety of types and amounts, which makes predicting the effects of tainted supplements a bit of a guessing game.

    Why is supplement adulteration common?

    At least in the U.S., supplement adulteration is probably a byproduct of how supplements are regulated.

    Under the current guidelines, supplement companies are not required to perform any tests establishing the quality of their products. And when unapproved drugs are found in supplements, the FDA will typically only warn the company that they should conduct a voluntary recall. Unfortunately, companies ignore this warning about half the time.

    The FDA can initiate a required recall when a supplement appears likely to cause harm, but even this does not always guarantee supplements will be pulled from shelves.

    Most people know the expression “snake oil salesman”, a term for a seller of fraudulent health products. The phrase actually derives from a case of supplement adulteration back in 1916, when it was reported that a popular line of snake oil liniment contained next to none of the claimed serpentine fat, instead being almost entirely mineral oil. This led the FDA to issue the eponymous snake oil salesman a $20 fine (about $500 in today’s money).

    It’s fair to say we’ve advanced quite a bit in the past 100 years, but regulation of supplements today hasn’t changed drastically since the days of well-dressed scammers selling bottles of rattlesnake fat.

    What can be done to avoid adulterated supplements?

    At Examine, we don’t recommend specific supplement brands. But there are some general guidelines that you can follow to reduce your chances of taking adulterated supplements.

    One tip is to only buy supplements certified by reputable third-party testers. These are companies with no financial affiliation to the supplement company that test the supplements to make sure they contain what they say and don’t have certain hidden ingredients. Some well-regarded testers include:

    • Informed Choice
    • Informed Sport
    • NSF Certified for Sport®
    • Banned Substances Control Group (BSCG) certifications (e.g., Certified Drug Free®)
    • United States Pharmacopeia (USP)
    • ConsumerLab
    • Labdoor

    Tested products will sometimes display logos from testers somewhere on the bottle.

    The FDA supplement recall page is a good resource for supplement recalls and safety alerts, though keep in mind that not all recalls will be listed on this page.

    Finally, you can also reduce your chances of taking an adulterated supplement by limiting how many you take. Rather than follow a biohacker-style 100 supplements per day regimen, limit your stack to the bare essentials.

    I’m a tiny bit biased, but I think Examine has the best collection of supplement research on the internet, so if you want help figuring out which supplements don’t live up to the hype, start here:


    Morgan Pfiffner
    Editor of Examine’s Study Summaries

    Quiz of the week


    Answer: Folic acid

    A deficiency in either folate or vitamin B12 can cause anemia. While folic acid can correct the anemia, it won’t treat a vitamin B12 deficiency. Left untreated, this could reduce cognitive function over time. Learn more about folic acid.